| Python 2.3 Quick Reference |
| |
| |
| 25 Jan 2003 upgraded by Raymond Hettinger for Python 2.3 |
| 16 May 2001 upgraded by Richard Gruet and Simon Brunning for Python 2.0 |
| 2000/07/18 upgraded by Richard Gruet, rgruet@intraware.com for Python 1.5.2 |
| from V1.3 ref |
| 1995/10/30, by Chris Hoffmann, choffman@vicorp.com |
| |
| Based on: |
| Python Bestiary, Author: Ken Manheimer, ken.manheimer@nist.gov |
| Python manuals, Authors: Guido van Rossum and Fred Drake |
| What's new in Python 2.0, Authors: A.M. Kuchling and Moshe Zadka |
| python-mode.el, Author: Tim Peters, tim_one@email.msn.com |
| |
| and the readers of comp.lang.python |
| |
| Python's nest: http://www.python.org Developement: http:// |
| python.sourceforge.net/ ActivePython : http://www.ActiveState.com/ASPN/ |
| Python/ |
| newsgroup: comp.lang.python Help desk: help@python.org |
| Resources: http://starship.python.net/ |
| http://www.vex.net/parnassus/ |
| http://aspn.activestate.com/ASPN/Cookbook/Python |
| FAQ: http://www.python.org/cgi-bin/faqw.py |
| Full documentation: http://www.python.org/doc/ |
| Excellent reference books: |
| Python Essential Reference by David Beazley (New Riders) |
| Python Pocket Reference by Mark Lutz (O'Reilly) |
| |
| |
| Invocation Options |
| |
| python [-diOStuUvxX?] [-c command | script | - ] [args] |
| |
| Invocation Options |
| Option Effect |
| -c cmd program passed in as string (terminates option list) |
| -d Outputs parser debugging information (also PYTHONDEBUG=x) |
| -E ignore environment variables (such as PYTHONPATH) |
| -h print this help message and exit |
| -i Inspect interactively after running script (also PYTHONINSPECT=x) and |
| force prompts, even if stdin appears not to be a terminal |
| -O optimize generated bytecode (a tad; also PYTHONOPTIMIZE=x) |
| -OO remove doc-strings in addition to the -O optimizations |
| -Q arg division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew |
| -S Don't perform 'import site' on initialization |
| -t Issue warnings about inconsistent tab usage (-tt: issue errors) |
| -u Unbuffered binary stdout and stderr (also PYTHONUNBUFFERED=x). |
| -v Verbose (trace import statements) (also PYTHONVERBOSE=x) |
| -W arg : warning control (arg is action:message:category:module:lineno) |
| -x Skip first line of source, allowing use of non-unix Forms of #!cmd |
| -? Help! |
| -c Specify the command to execute (see next section). This terminates the |
| command option list (following options are passed as arguments to the command). |
| the name of a python file (.py) to execute read from stdin. |
| script Anything afterward is passed as options to python script or command, |
| not interpreted as an option to interpreter itself. |
| args passed to script or command (in sys.argv[1:]) |
| If no script or command, Python enters interactive mode. |
| |
| * Available IDEs in std distrib: IDLE (tkinter based, portable), Pythonwin |
| (Windows). |
| |
| |
| |
| Environment variables |
| |
| Environment variables |
| Variable Effect |
| PYTHONHOME Alternate prefix directory (or prefix;exec_prefix). The |
| default module search path uses prefix/lib |
| Augments the default search path for module files. The format |
| is the same as the shell's $PATH: one or more directory |
| pathnames separated by ':' or ';' without spaces around |
| (semi-)colons! |
| PYTHONPATH On Windows first search for Registry key HKEY_LOCAL_MACHINE\ |
| Software\Python\PythonCore\x.y\PythonPath (default value). You |
| may also define a key named after your application with a |
| default string value giving the root directory path of your |
| app. |
| If this is the name of a readable file, the Python commands in |
| PYTHONSTARTUP that file are executed before the first prompt is displayed in |
| interactive mode (no default). |
| PYTHONDEBUG If non-empty, same as -d option |
| PYTHONINSPECT If non-empty, same as -i option |
| PYTHONSUPPRESS If non-empty, same as -s option |
| PYTHONUNBUFFERED If non-empty, same as -u option |
| PYTHONVERBOSE If non-empty, same as -v option |
| PYTHONCASEOK If non-empty, ignore case in file/module names (imports) |
| |
| |
| |
| |
| Notable lexical entities |
| |
| Keywords |
| |
| and del for is raise |
| assert elif from lambda return |
| break else global not try |
| class except if or while |
| continue exec import pass yield |
| def finally in print |
| |
| * (list of keywords in std module: keyword) |
| * Illegitimate Tokens (only valid in strings): @ $ ? |
| * A statement must all be on a single line. To break a statement over |
| multiple lines use "\", as with the C preprocessor. |
| Exception: can always break when inside any (), [], or {} pair, or in |
| triple-quoted strings. |
| * More than one statement can appear on a line if they are separated with |
| semicolons (";"). |
| * Comments start with "#" and continue to end of line. |
| |
| Identifiers |
| |
| (letter | "_") (letter | digit | "_")* |
| |
| * Python identifiers keywords, attributes, etc. are case-sensitive. |
| * Special forms: _ident (not imported by 'from module import *'); __ident__ |
| (system defined name); |
| __ident (class-private name mangling) |
| |
| Strings |
| |
| "a string enclosed by double quotes" |
| 'another string delimited by single quotes and with a " inside' |
| '''a string containing embedded newlines and quote (') marks, can be |
| delimited with triple quotes.''' |
| """ may also use 3- double quotes as delimiters """ |
| u'a unicode string' U"Another unicode string" |
| r'a raw string where \ are kept (literalized): handy for regular |
| expressions and windows paths!' |
| R"another raw string" -- raw strings cannot end with a \ |
| ur'a unicode raw string' UR"another raw unicode" |
| |
| Use \ at end of line to continue a string on next line. |
| adjacent strings are concatened, e.g. 'Monty' ' Python' is the same as |
| 'Monty Python'. |
| u'hello' + ' world' --> u'hello world' (coerced to unicode) |
| |
| String Literal Escapes |
| |
| \newline Ignored (escape newline) |
| \\ Backslash (\) \e Escape (ESC) \v Vertical Tab (VT) |
| \' Single quote (') \f Formfeed (FF) \OOO char with octal value OOO |
| \" Double quote (") \n Linefeed (LF) |
| \a Bell (BEL) \r Carriage Return (CR) \xHH char with hex value HH |
| \b Backspace (BS) \t Horizontal Tab (TAB) |
| \uHHHH unicode char with hex value HHHH, can only be used in unicode string |
| \UHHHHHHHH unicode char with hex value HHHHHHHH, can only be used in unicode string |
| \AnyOtherChar is left as-is |
| |
| * NUL byte (\000) is NOT an end-of-string marker; NULs may be embedded in |
| strings. |
| * Strings (and tuples) are immutable: they cannot be modified. |
| |
| Numbers |
| |
| Decimal integer: 1234, 1234567890546378940L (or l) |
| Octal integer: 0177, 0177777777777777777 (begin with a 0) |
| Hex integer: 0xFF, 0XFFFFffffFFFFFFFFFF (begin with 0x or 0X) |
| Long integer (unlimited precision): 1234567890123456 |
| Float (double precision): 3.14e-10, .001, 10., 1E3 |
| Complex: 1J, 2+3J, 4+5j (ends with J or j, + separates (float) real and |
| imaginary parts) |
| |
| Sequences |
| |
| * String of length 0, 1, 2 (see above) |
| '', '1', "12", 'hello\n' |
| * Tuple of length 0, 1, 2, etc: |
| () (1,) (1,2) # parentheses are optional if len > 0 |
| * List of length 0, 1, 2, etc: |
| [] [1] [1,2] |
| |
| Indexing is 0-based. Negative indices (usually) mean count backwards from end |
| of sequence. |
| |
| Sequence slicing [starting-at-index : but-less-than-index]. Start defaults to |
| '0'; End defaults to 'sequence-length'. |
| |
| a = (0,1,2,3,4,5,6,7) |
| a[3] ==> 3 |
| a[-1] ==> 7 |
| a[2:4] ==> (2, 3) |
| a[1:] ==> (1, 2, 3, 4, 5, 6, 7) |
| a[:3] ==> (0, 1, 2) |
| a[:] ==> (0,1,2,3,4,5,6,7) # makes a copy of the sequence. |
| |
| Dictionaries (Mappings) |
| |
| {} # Zero length empty dictionary |
| {1 : 'first'} # Dictionary with one (key, value) pair |
| {1 : 'first', 'next': 'second'} |
| dict([('one',1),('two',2)]) # Construct a dict from an item list |
| dict('one'=1, 'two'=2) # Construct a dict using keyword args |
| dict.fromkeys(['one', 'keys']) # Construct a dict from a sequence |
| |
| Operators and their evaluation order |
| |
| Operators and their evaluation order |
| Highest Operator Comment |
| (...) [...] {...} `...` Tuple, list & dict. creation; string |
| conv. |
| s[i] s[i:j] s.attr f(...) indexing & slicing; attributes, fct |
| calls |
| +x, -x, ~x Unary operators |
| x**y Power |
| x*y x/y x%y x//y mult, division, modulo, floor division |
| x+y x-y addition, subtraction |
| x<<y x>>y Bit shifting |
| x&y Bitwise and |
| x^y Bitwise exclusive or |
| x|y Bitwise or |
| x<y x<=y x>y x>=y x==y x!=y Comparison, |
| x<>y identity, |
| x is y x is not y membership |
| x in s x not in s |
| not x boolean negation |
| x and y boolean and |
| x or y boolean or |
| Lowest lambda args: expr anonymous function |
| |
| Alternate names are defined in module operator (e.g. __add__ and add for +) |
| Most operators are overridable. |
| |
| Many binary operators also support augmented assignment: |
| x += 1 # Same as x = x + 1 |
| |
| |
| Basic Types and Their Operations |
| |
| Comparisons (defined between *any* types) |
| |
| Comparisons |
| Comparison Meaning Notes |
| < strictly less than (1) |
| <= less than or equal to |
| > strictly greater than |
| >= greater than or equal to |
| == equal to |
| != or <> not equal to |
| is object identity (2) |
| is not negated object identity (2) |
| |
| Notes : |
| Comparison behavior can be overridden for a given class by defining special |
| method __cmp__. |
| The above comparisons return True or False which are of type bool |
| (a subclass of int) and behave exactly as 1 or 0 except for their type and |
| that they print as True or False instead of 1 or 0. |
| (1) X < Y < Z < W has expected meaning, unlike C |
| (2) Compare object identities (i.e. id(object)), not object values. |
| |
| Boolean values and operators |
| |
| Boolean values and operators |
| Value or Operator Returns Notes |
| None, numeric zeros, empty sequences and False |
| mappings |
| all other values True |
| not x True if x is False, else |
| True |
| x or y if x is False then y, else (1) |
| x |
| x and y if x is False then x, else (1) |
| y |
| |
| Notes : |
| Truth testing behavior can be overridden for a given class by defining |
| special method __nonzero__. |
| (1) Evaluate second arg only if necessary to determine outcome. |
| |
| None |
| |
| None is used as default return value on functions. Built-in single object |
| with type NoneType. |
| Input that evaluates to None does not print when running Python |
| interactively. |
| |
| Numeric types |
| |
| Floats, integers and long integers. |
| |
| Floats are implemented with C doubles. |
| Integers are implemented with C longs. |
| Long integers have unlimited size (only limit is system resources) |
| |
| Operators on all numeric types |
| |
| Operators on all numeric types |
| Operation Result |
| abs(x) the absolute value of x |
| int(x) x converted to integer |
| long(x) x converted to long integer |
| float(x) x converted to floating point |
| -x x negated |
| +x x unchanged |
| x + y the sum of x and y |
| x - y difference of x and y |
| x * y product of x and y |
| x / y quotient of x and y |
| x % y remainder of x / y |
| divmod(x, y) the tuple (x/y, x%y) |
| x ** y x to the power y (the same as pow(x, y)) |
| |
| Bit operators on integers and long integers |
| |
| Bit operators |
| Operation >Result |
| ~x the bits of x inverted |
| x ^ y bitwise exclusive or of x and y |
| x & y bitwise and of x and y |
| x | y bitwise or of x and y |
| x << n x shifted left by n bits |
| x >> n x shifted right by n bits |
| |
| Complex Numbers |
| |
| * represented as a pair of machine-level double precision floating point |
| numbers. |
| * The real and imaginary value of a complex number z can be retrieved through |
| the attributes z.real and z.imag. |
| |
| Numeric exceptions |
| |
| TypeError |
| raised on application of arithmetic operation to non-number |
| OverflowError |
| numeric bounds exceeded |
| ZeroDivisionError |
| raised when zero second argument of div or modulo op |
| FloatingPointError |
| raised when a floating point operation fails |
| |
| Operations on all sequence types (lists, tuples, strings) |
| |
| Operations on all sequence types |
| Operation Result Notes |
| x in s True if an item of s is equal to x, else False |
| x not in s False if an item of s is equal to x, else True |
| for x in s: loops over the sequence |
| s + t the concatenation of s and t |
| s * n, n*s n copies of s concatenated |
| s[i] i'th item of s, origin 0 (1) |
| s[i:j] slice of s from i (included) to j (excluded) (1), (2) |
| len(s) length of s |
| min(s) smallest item of s |
| max(s) largest item of (s) |
| iter(s) returns an iterator over s. iterators define __iter__ and next() |
| |
| Notes : |
| (1) if i or j is negative, the index is relative to the end of the string, |
| ie len(s)+ i or len(s)+j is |
| substituted. But note that -0 is still 0. |
| (2) The slice of s from i to j is defined as the sequence of items with |
| index k such that i <= k < j. |
| If i or j is greater than len(s), use len(s). If i is omitted, use |
| len(s). If i is greater than or |
| equal to j, the slice is empty. |
| |
| Operations on mutable (=modifiable) sequences (lists) |
| |
| Operations on mutable sequences |
| Operation Result Notes |
| s[i] =x item i of s is replaced by x |
| s[i:j] = t slice of s from i to j is replaced by t |
| del s[i:j] same as s[i:j] = [] |
| s.append(x) same as s[len(s) : len(s)] = [x] |
| s.count(x) return number of i's for which s[i] == x |
| s.extend(x) same as s[len(s):len(s)]= x |
| s.index(x) return smallest i such that s[i] == x (1) |
| s.insert(i, x) same as s[i:i] = [x] if i >= 0 |
| s.pop([i]) same as x = s[i]; del s[i]; return x (4) |
| s.remove(x) same as del s[s.index(x)] (1) |
| s.reverse() reverse the items of s in place (3) |
| s.sort([cmpFct]) sort the items of s in place (2), (3) |
| |
| Notes : |
| (1) raise a ValueError exception when x is not found in s (i.e. out of |
| range). |
| (2) The sort() method takes an optional argument specifying a comparison |
| fct of 2 arguments (list items) which should |
| return -1, 0, or 1 depending on whether the 1st argument is |
| considered smaller than, equal to, or larger than the 2nd |
| argument. Note that this slows the sorting process down considerably. |
| (3) The sort() and reverse() methods modify the list in place for economy |
| of space when sorting or reversing a large list. |
| They don't return the sorted or reversed list to remind you of this |
| side effect. |
| (4) [New 1.5.2] The optional argument i defaults to -1, so that by default the last |
| item is removed and returned. |
| |
| |
| |
| Operations on mappings (dictionaries) |
| |
| Operations on mappings |
| Operation Result Notes |
| len(d) the number of items in d |
| d[k] the item of d with key k (1) |
| d[k] = x set d[k] to x |
| del d[k] remove d[k] from d (1) |
| d.clear() remove all items from d |
| d.copy() a shallow copy of d |
| d.get(k,defaultval) the item of d with key k (4) |
| d.has_key(k) True if d has key k, else False |
| d.items() a copy of d's list of (key, item) pairs (2) |
| d.iteritems() an iterator over (key, value) pairs (7) |
| d.iterkeys() an iterator over the keys of d (7) |
| d.itervalues() an iterator over the values of d (7) |
| d.keys() a copy of d's list of keys (2) |
| d1.update(d2) for k, v in d2.items(): d1[k] = v (3) |
| d.values() a copy of d's list of values (2) |
| d.pop(k) remove d[k] and return its value |
| d.popitem() remove and return an arbitrary (6) |
| (key, item) pair |
| d.setdefault(k,defaultval) the item of d with key k (5) |
| |
| Notes : |
| TypeError is raised if key is not acceptable |
| (1) KeyError is raised if key k is not in the map |
| (2) Keys and values are listed in random order |
| (3) d2 must be of the same type as d1 |
| (4) Never raises an exception if k is not in the map, instead it returns |
| defaultVal. |
| defaultVal is optional, when not provided and k is not in the map, |
| None is returned. |
| (5) Never raises an exception if k is not in the map, instead it returns |
| defaultVal, and adds k to map with value defaultVal. defaultVal is |
| optional. When not provided and k is not in the map, None is returned and |
| added to map. |
| (6) Raises a KeyError if the dictionary is emtpy. |
| (7) While iterating over a dictionary, the values may be updated but |
| the keys cannot be changed. |
| |
| Operations on strings |
| |
| Note that these string methods largely (but not completely) supersede the |
| functions available in the string module. |
| |
| |
| Operations on strings |
| Operation Result Notes |
| s.capitalize() return a copy of s with only its first character |
| capitalized. |
| s.center(width) return a copy of s centered in a string of length width (1) |
| . |
| s.count(sub[ return the number of occurrences of substring sub in (2) |
| ,start[,end]]) string s. |
| s.decode(([ return a decoded version of s. (3) |
| encoding |
| [,errors]]) |
| s.encode([ return an encoded version of s. Default encoding is the |
| encoding current default string encoding. (3) |
| [,errors]]) |
| s.endswith(suffix return true if s ends with the specified suffix, (2) |
| [,start[,end]]) otherwise return False. |
| s.expandtabs([ return a copy of s where all tab characters are (4) |
| tabsize]) expanded using spaces. |
| s.find(sub[,start return the lowest index in s where substring sub is (2) |
| [,end]]) found. Return -1 if sub is not found. |
| s.index(sub[ like find(), but raise ValueError when the substring is (2) |
| ,start[,end]]) not found. |
| s.isalnum() return True if all characters in s are alphanumeric, (5) |
| False otherwise. |
| s.isalpha() return True if all characters in s are alphabetic, (5) |
| False otherwise. |
| s.isdigit() return True if all characters in s are digit (5) |
| characters, False otherwise. |
| s.islower() return True if all characters in s are lowercase, False (6) |
| otherwise. |
| s.isspace() return True if all characters in s are whitespace (5) |
| characters, False otherwise. |
| s.istitle() return True if string s is a titlecased string, False (7) |
| otherwise. |
| s.isupper() return True if all characters in s are uppercase, False (6) |
| otherwise. |
| s.join(seq) return a concatenation of the strings in the sequence |
| seq, seperated by 's's. |
| s.ljust(width) return s left justified in a string of length width. (1), |
| (8) |
| s.lower() return a copy of s converted to lowercase. |
| s.lstrip() return a copy of s with leading whitespace removed. |
| s.replace(old, return a copy of s with all occurrences of substring (9) |
| new[, maxsplit]) old replaced by new. |
| s.rfind(sub[ return the highest index in s where substring sub is (2) |
| ,start[,end]]) found. Return -1 if sub is not found. |
| s.rindex(sub[ like rfind(), but raise ValueError when the substring (2) |
| ,start[,end]]) is not found. |
| s.rjust(width) return s right justified in a string of length width. (1), |
| (8) |
| s.rstrip() return a copy of s with trailing whitespace removed. |
| s.split([sep[ return a list of the words in s, using sep as the (10) |
| ,maxsplit]]) delimiter string. |
| s.splitlines([ return a list of the lines in s, breaking at line (11) |
| keepends]) boundaries. |
| s.startswith return true if s starts with the specified prefix, |
| (prefix[,start[ otherwise return false. (2) |
| ,end]]) |
| s.strip() return a copy of s with leading and trailing whitespace |
| removed. |
| s.swapcase() return a copy of s with uppercase characters converted |
| to lowercase and vice versa. |
| return a titlecased copy of s, i.e. words start with |
| s.title() uppercase characters, all remaining cased characters |
| are lowercase. |
| s.translate(table return a copy of s mapped through translation table (12) |
| [,deletechars]) table. |
| s.upper() return a copy of s converted to uppercase. |
| s.zfill(width) return a string padded with zeroes on the left side and |
| sliding a minus sign left if necessary. never truncates. |
| |
| Notes : |
| (1) Padding is done using spaces. |
| (2) If optional argument start is supplied, substring s[start:] is |
| processed. If optional arguments start and end are supplied, substring s[start: |
| end] is processed. |
| (3) Optional argument errors may be given to set a different error handling |
| scheme. The default for errors is 'strict', meaning that encoding errors raise |
| a ValueError. Other possible values are 'ignore' and 'replace'. |
| (4) If optional argument tabsize is not given, a tab size of 8 characters |
| is assumed. |
| (5) Returns false if string s does not contain at least one character. |
| (6) Returns false if string s does not contain at least one cased |
| character. |
| (7) A titlecased string is a string in which uppercase characters may only |
| follow uncased characters and lowercase characters only cased ones. |
| (8) s is returned if width is less than len(s). |
| (9) If the optional argument maxsplit is given, only the first maxsplit |
| occurrences are replaced. |
| (10) If sep is not specified or None, any whitespace string is a separator. |
| If maxsplit is given, at most maxsplit splits are done. |
| (11) Line breaks are not included in the resulting list unless keepends is |
| given and true. |
| (12) table must be a string of length 256. All characters occurring in the |
| optional argument deletechars are removed prior to translation. |
| |
| String formatting with the % operator |
| |
| formatString % args--> evaluates to a string |
| |
| * formatString uses C printf format codes : %, c, s, i, d, u, o, x, X, e, E, |
| f, g, G, r (details below). |
| * Width and precision may be a * to specify that an integer argument gives |
| the actual width or precision. |
| * The flag characters -, +, blank, # and 0 are understood. (details below) |
| * %s will convert any type argument to string (uses str() function) |
| * args may be a single arg or a tuple of args |
| |
| '%s has %03d quote types.' % ('Python', 2) # => 'Python has 002 quote types.' |
| |
| * Right-hand-side can also be a mapping: |
| |
| a = '%(lang)s has %(c)03d quote types.' % {'c':2, 'lang':'Python} |
| (vars() function very handy to use on right-hand-side.) |
| |
| Format codes |
| Conversion Meaning |
| d Signed integer decimal. |
| i Signed integer decimal. |
| o Unsigned octal. |
| u Unsigned decimal. |
| x Unsigned hexidecimal (lowercase). |
| X Unsigned hexidecimal (uppercase). |
| e Floating point exponential format (lowercase). |
| E Floating point exponential format (uppercase). |
| f Floating point decimal format. |
| F Floating point decimal format. |
| g Same as "e" if exponent is greater than -4 or less than precision, |
| "f" otherwise. |
| G Same as "E" if exponent is greater than -4 or less than precision, |
| "F" otherwise. |
| c Single character (accepts integer or single character string). |
| r String (converts any python object using repr()). |
| s String (converts any python object using str()). |
| % No argument is converted, results in a "%" character in the result. |
| (The complete specification is %%.) |
| |
| Conversion flag characters |
| Flag Meaning |
| # The value conversion will use the ``alternate form''. |
| 0 The conversion will be zero padded. |
| - The converted value is left adjusted (overrides "-"). |
| (a space) A blank should be left before a positive number (or empty |
| string) produced by a signed conversion. |
| + A sign character ("+" or "-") will precede the conversion (overrides a |
| "space" flag). |
| |
| File Objects |
| |
| Created with built-in function open; may be created by other modules' functions |
| as well. |
| |
| Operators on file objects |
| |
| File operations |
| Operation Result |
| f.close() Close file f. |
| f.fileno() Get fileno (fd) for file f. |
| f.flush() Flush file f's internal buffer. |
| f.isatty() True if file f is connected to a tty-like dev, else False. |
| f.read([size]) Read at most size bytes from file f and return as a string |
| object. If size omitted, read to EOF. |
| f.readline() Read one entire line from file f. |
| f.readlines() Read until EOF with readline() and return list of lines read. |
| Set file f's position, like "stdio's fseek()". |
| f.seek(offset[, whence == 0 then use absolute indexing. |
| whence=0]) whence == 1 then offset relative to current pos. |
| whence == 2 then offset relative to file end. |
| f.tell() Return file f's current position (byte offset). |
| f.write(str) Write string to file f. |
| f.writelines(list Write list of strings to file f. |
| ) |
| |
| File Exceptions |
| |
| EOFError |
| End-of-file hit when reading (may be raised many times, e.g. if f is a |
| tty). |
| IOError |
| Other I/O-related I/O operation failure. |
| OSError |
| OS system call failed. |
| |
| |
| Advanced Types |
| |
| -See manuals for more details - |
| + Module objects |
| + Class objects |
| + Class instance objects |
| + Type objects (see module: types) |
| + File objects (see above) |
| + Slice objects |
| + XRange objects |
| + Callable types: |
| o User-defined (written in Python): |
| # User-defined Function objects |
| # User-defined Method objects |
| o Built-in (written in C): |
| # Built-in Function objects |
| # Built-in Method objects |
| + Internal Types: |
| o Code objects (byte-compile executable Python code: bytecode) |
| o Frame objects (execution frames) |
| o Traceback objects (stack trace of an exception) |
| |
| |
| Statements |
| |
| pass -- Null statement |
| del name[,name]* -- Unbind name(s) from object. Object will be indirectly |
| (and automatically) deleted only if no longer referenced. |
| print [>> fileobject,] [s1 [, s2 ]* [,] |
| -- Writes to sys.stdout, or to fileobject if supplied. |
| Puts spaces between arguments. Puts newline at end |
| unless statement ends with comma. |
| Print is not required when running interactively, |
| simply typing an expression will print its value, |
| unless the value is None. |
| exec x [in globals [,locals]] |
| -- Executes x in namespaces provided. Defaults |
| to current namespaces. x can be a string, file |
| object or a function object. |
| callable(value,... [id=value], [*args], [**kw]) |
| -- Call function callable with parameters. Parameters can |
| be passed by name or be omitted if function |
| defines default values. E.g. if callable is defined as |
| "def callable(p1=1, p2=2)" |
| "callable()" <=> "callable(1, 2)" |
| "callable(10)" <=> "callable(10, 2)" |
| "callable(p2=99)" <=> "callable(1, 99)" |
| *args is a tuple of positional arguments. |
| **kw is a dictionary of keyword arguments. |
| |
| Assignment operators |
| |
| Caption |
| Operator Result Notes |
| a = b Basic assignment - assign object b to label a (1) |
| a += b Roughly equivalent to a = a + b (2) |
| a -= b Roughly equivalent to a = a - b (2) |
| a *= b Roughly equivalent to a = a * b (2) |
| a /= b Roughly equivalent to a = a / b (2) |
| a %= b Roughly equivalent to a = a % b (2) |
| a **= b Roughly equivalent to a = a ** b (2) |
| a &= b Roughly equivalent to a = a & b (2) |
| a |= b Roughly equivalent to a = a | b (2) |
| a ^= b Roughly equivalent to a = a ^ b (2) |
| a >>= b Roughly equivalent to a = a >> b (2) |
| a <<= b Roughly equivalent to a = a << b (2) |
| |
| Notes : |
| (1) Can unpack tuples, lists, and strings. |
| first, second = a[0:2]; [f, s] = range(2); c1,c2,c3='abc' |
| Tip: x,y = y,x swaps x and y. |
| (2) Not exactly equivalent - a is evaluated only once. Also, where |
| possible, operation performed in-place - a is modified rather than |
| replaced. |
| |
| Control Flow |
| |
| if condition: suite |
| [elif condition: suite]* |
| [else: suite] -- usual if/else_if/else statement |
| while condition: suite |
| [else: suite] |
| -- usual while statement. "else" suite is executed |
| after loop exits, unless the loop is exited with |
| "break" |
| for element in sequence: suite |
| [else: suite] |
| -- iterates over sequence, assigning each element to element. |
| Use built-in range function to iterate a number of times. |
| "else" suite executed at end unless loop exited |
| with "break" |
| break -- immediately exits "for" or "while" loop |
| continue -- immediately does next iteration of "for" or "while" loop |
| return [result] -- Exits from function (or method) and returns result (use a tuple to |
| return more than one value). If no result given, then returns None. |
| yield result -- Freezes the execution frame of a generator and returns the result |
| to the iterator's .next() method. Upon the next call to next(), |
| resumes execution at the frozen point with all of the local variables |
| still intact. |
| |
| Exception Statements |
| |
| assert expr[, message] |
| -- expr is evaluated. if false, raises exception AssertionError |
| with message. Inhibited if __debug__ is 0. |
| try: suite1 |
| [except [exception [, value]: suite2]+ |
| [else: suite3] |
| -- statements in suite1 are executed. If an exception occurs, look |
| in "except" clauses for matching <exception>. If matches or bare |
| "except" execute suite of that clause. If no exception happens |
| suite in "else" clause is executed after suite1. |
| If exception has a value, it is put in value. |
| exception can also be tuple of exceptions, e.g. |
| "except (KeyError, NameError), val: print val" |
| try: suite1 |
| finally: suite2 |
| -- statements in suite1 are executed. If no |
| exception, execute suite2 (even if suite1 is |
| exited with a "return", "break" or "continue" |
| statement). If exception did occur, executes |
| suite2 and then immediately reraises exception. |
| raise exception [,value [, traceback]] |
| -- raises exception with optional value |
| value. Arg traceback specifies a traceback object to |
| use when printing the exception's backtrace. |
| raise -- a raise statement without arguments re-raises |
| the last exception raised in the current function |
| An exception is either a string (object) or a class instance. |
| Can create a new one simply by creating a new string: |
| |
| my_exception = 'You did something wrong' |
| try: |
| if bad: |
| raise my_exception, bad |
| except my_exception, value: |
| print 'Oops', value |
| |
| Exception classes must be derived from the predefined class: Exception, e.g.: |
| class text_exception(Exception): pass |
| try: |
| if bad: |
| raise text_exception() |
| # This is a shorthand for the form |
| # "raise <class>, <instance>" |
| except Exception: |
| print 'Oops' |
| # This will be printed because |
| # text_exception is a subclass of Exception |
| When an error message is printed for an unhandled exception which is a |
| class, the class name is printed, then a colon and a space, and |
| finally the instance converted to a string using the built-in function |
| str(). |
| All built-in exception classes derives from StandardError, itself |
| derived from Exception. |
| |
| Name Space Statements |
| |
| [1.51: On Mac & Windows, the case of module file names must now match the case |
| as used |
| in the import statement] |
| Packages (>1.5): a package is a name space which maps to a directory including |
| module(s) and the special initialization module '__init__.py' |
| (possibly empty). Packages/dirs can be nested. You address a |
| module's symbol via '[package.[package...]module.symbol's. |
| import module1 [as name1] [, module2]* |
| -- imports modules. Members of module must be |
| referred to by qualifying with [package.]module name: |
| "import sys; print sys.argv:" |
| "import package1.subpackage.module; package1.subpackage.module.foo()" |
| module1 renamed as name1, if supplied. |
| from module import name1 [as othername1] [, name2]* |
| -- imports names from module module in current namespace. |
| "from sys import argv; print argv" |
| "from package1 import module; module.foo()" |
| "from package1.module import foo; foo()" |
| name1 renamed as othername1, if supplied. |
| from module import * |
| -- imports all names in module, except those starting with "_"; |
| *to be used sparsely, beware of name clashes* : |
| "from sys import *; print argv" |
| "from package.module import *; print x' |
| NB: "from package import *" only imports the symbols defined |
| in the package's __init__.py file, not those in the |
| template modules! |
| global name1 [, name2]* |
| -- names are from global scope (usually meaning from module) |
| rather than local (usually meaning only in function). |
| -- E.g. in fct without "global" statements, assuming |
| "a" is name that hasn't been used in fct or module |
| so far: |
| -Try to read from "a" -> NameError |
| -Try to write to "a" -> creates "a" local to fcn |
| -If "a" not defined in fct, but is in module, then |
| -Try to read from "a", gets value from module |
| -Try to write to "a", creates "a" local to fct |
| But note "a[0]=3" starts with search for "a", |
| will use to global "a" if no local "a". |
| |
| Function Definition |
| |
| def func_id ([param_list]): suite |
| -- Creates a function object & binds it to name func_id. |
| |
| param_list ::= [id [, id]*] |
| id ::= value | id = value | *id | **id |
| [Args are passed by value.Thus only args representing a mutable object |
| can be modified (are inout parameters). Use a tuple to return more than |
| one value] |
| |
| Example: |
| def test (p1, p2 = 1+1, *rest, **keywords): |
| -- Parameters with "=" have default value (v is |
| evaluated when function defined). |
| If list has "*id" then id is assigned a tuple of |
| all remaining args passed to function (like C vararg) |
| If list has "**id" then id is assigned a dictionary of |
| all extra arguments passed as keywords. |
| |
| Class Definition |
| |
| class <class_id> [(<super_class1> [,<super_class2>]*)]: <suite> |
| -- Creates a class object and assigns it name <class_id> |
| <suite> may contain local "defs" of class methods and |
| assignments to class attributes. |
| Example: |
| class my_class (class1, class_list[3]): ... |
| Creates a class object inheriting from both "class1" and whatever |
| class object "class_list[3]" evaluates to. Assigns new |
| class object to name "my_class". |
| - First arg to class methods is always instance object, called 'self' |
| by convention. |
| - Special method __init__() is called when instance is created. |
| - Special method __del__() called when no more reference to object. |
| - Create instance by "calling" class object, possibly with arg |
| (thus instance=apply(aClassObject, args...) creates an instance!) |
| - In current implementation, can't subclass off built-in |
| classes. But can "wrap" them, see UserDict & UserList modules, |
| and see __getattr__() below. |
| Example: |
| class c (c_parent): |
| def __init__(self, name): self.name = name |
| def print_name(self): print "I'm", self.name |
| def call_parent(self): c_parent.print_name(self) |
| instance = c('tom') |
| print instance.name |
| 'tom' |
| instance.print_name() |
| "I'm tom" |
| Call parent's super class by accessing parent's method |
| directly and passing "self" explicitly (see "call_parent" |
| in example above). |
| Many other special methods available for implementing |
| arithmetic operators, sequence, mapping indexing, etc. |
| |
| Documentation Strings |
| |
| Modules, classes and functions may be documented by placing a string literal by |
| itself as the first statement in the suite. The documentation can be retrieved |
| by getting the '__doc__' attribute from the module, class or function. |
| Example: |
| class C: |
| "A description of C" |
| def __init__(self): |
| "A description of the constructor" |
| # etc. |
| Then c.__doc__ == "A description of C". |
| Then c.__init__.__doc__ == "A description of the constructor". |
| |
| Others |
| |
| lambda [param_list]: returnedExpr |
| -- Creates an anonymous function. returnedExpr must be |
| an expression, not a statement (e.g., not "if xx:...", |
| "print xxx", etc.) and thus can't contain newlines. |
| Used mostly for filter(), map(), reduce() functions, and GUI callbacks.. |
| List comprehensions |
| result = [expression for item1 in sequence1 [if condition1] |
| [for item2 in sequence2 ... for itemN in sequenceN] |
| ] |
| is equivalent to: |
| result = [] |
| for item1 in sequence1: |
| for item2 in sequence2: |
| ... |
| for itemN in sequenceN: |
| if (condition1) and furthur conditions: |
| result.append(expression) |
| |
| |
| |
| Built-In Functions |
| |
| Built-In Functions |
| Function Result |
| __import__(name[, Imports module within the given context (see lib ref for |
| globals[, locals[, more details) |
| fromlist]]]) |
| abs(x) Return the absolute value of number x. |
| bool(x) Returns True when the argument x is true and False otherwise. |
| buffer(obj) Creates a buffer reference to an object. |
| callable(x) Returns True if x callable, else False. |
| chr(i) Returns one-character string whose ASCII code isinteger i |
| classmethod(f) Converts a function f, into a method with the class as the |
| first argument. Useful for creating alternative constructors. |
| cmp(x,y) Returns negative, 0, positive if x <, ==, > to y |
| compile(string, from which the code was read, or eg. '<string>'if not read |
| filename, kind) from file.kind can be 'eval' if string is a single stmt, or |
| 'single' which prints the output of expression statements |
| thatevaluate to something else than None, or be 'exec'. |
| complex(real[, Builds a complex object (can also be done using J or j |
| image]) suffix,e.g. 1+3J) |
| delattr(obj, name) deletes attribute named name of object obj <=> del obj.name |
| If no args, returns the list of names in current |
| dict([items]) Create a new dictionary from the specified item list. |
| dir([object]) localsymbol table. With a module, class or class |
| instanceobject as arg, returns list of names in its attr. |
| dict. |
| divmod(a,b) Returns tuple of (a/b, a%b) |
| enumerate(seq) Return a iterator giving: (0, seq[0]), (1, seq[1]), ... |
| eval(s[, globals[, Eval string s in (optional) globals, locals contexts.s must |
| locals]]) have no NUL's or newlines. s can also be acode object. |
| Example: x = 1; incr_x = eval('x + 1') |
| execfile(file[, Executes a file without creating a new module, unlike |
| globals[, locals]]) import. |
| file() Synonym for open(). |
| filter(function, Constructs a list from those elements of sequence for which |
| sequence) function returns true. function takes one parameter. |
| float(x) Converts a number or a string to floating point. |
| getattr(object, [<default> arg added in 1.5.2]Gets attribute called name |
| name[, default])) from object,e.g. getattr(x, 'f') <=> x.f). If not found, |
| raisesAttributeError or returns default if specified. |
| globals() Returns a dictionary containing current global variables. |
| hasattr(object, Returns true if object has attr called name. |
| name) |
| hash(object) Returns the hash value of the object (if it has one) |
| help(f) Display documentation on object f. |
| hex(x) Converts a number x to a hexadecimal string. |
| id(object) Returns a unique 'identity' integer for an object. |
| int(x[, base]) base paramenter specifies base from which to convert string |
| values. |
| intern(aString) Enters aString in the table of "interned strings" |
| andreturns the string. Interned strings are 'immortals'. |
| isinstance(obj, returns true if obj is an instance of class. Ifissubclass |
| class) (A,B) then isinstance(x,A) => isinstance(x,B) |
| issubclass(class1, returns true if class1 is derived from class2 |
| class2) |
| Returns the length (the number of items) of an object |
| iter(collection) Returns an iterator over the collection. |
| len(obj) (sequence, dictionary, or instance of class implementing |
| __len__). |
| list(sequence) Converts sequence into a list. If already a list,returns a |
| copy of it. |
| locals() Returns a dictionary containing current local variables. |
| Converts a number or a string to a long integer. Optional |
| long(x[, base]) base paramenter specifies base from which to convert string |
| values. |
| Applies function to every item of list and returns a listof |
| map(function, list, the results. If additional arguments are passed,function |
| ...) must take that many arguments and it is givento function on |
| each call. |
| max(seq) Returns the largest item of the non-empty sequence seq. |
| min(seq) Returns the smallest item of a non-empty sequence seq. |
| oct(x) Converts a number to an octal string. |
| open(filename [, Returns a new file object. First two args are same asthose |
| mode='r', [bufsize= for C's "stdio open" function. bufsize is 0for unbuffered, |
| implementation 1 for line-buffered, negative forsys-default, all else, of |
| dependent]]) (about) given size. |
| ord(c) Returns integer ASCII value of c (a string of len 1). Works |
| with Unicode char. |
| object() Create a base type. Used as a superclass for new-style objects. |
| open(name Open a file. |
| [, mode |
| [, buffering]]) |
| pow(x, y [, z]) Returns x to power y [modulo z]. See also ** operator. |
| property() Created a property with access controlled by functions. |
| range(start [,end Returns list of ints from >= start and < end.With 1 arg, |
| [, step]]) list from 0..arg-1With 2 args, list from start..end-1With 3 |
| args, list from start up to end by step |
| reduce(f, list [, Applies the binary function f to the items oflist so as to |
| init]) reduce the list to a single value.If init given, it is |
| "prepended" to list. |
| Re-parses and re-initializes an already imported module. |
| Useful in interactive mode, if you want to reload amodule |
| reload(module) after fixing it. If module was syntacticallycorrect but had |
| an error in initialization, mustimport it one more time |
| before calling reload(). |
| Returns a string containing a printable and if possible |
| repr(object) evaluable representation of an object. <=> `object` |
| (usingbackquotes). Class redefinissable (__repr__). See |
| also str() |
| round(x, n=0) Returns the floating point value x rounded to n digitsafter |
| the decimal point. |
| setattr(object, This is the counterpart of getattr().setattr(o, 'foobar', |
| name, value) 3) <=> o.foobar = 3Creates attribute if it doesn't exist! |
| slice([start,] stop Returns a slice object representing a range, with R/ |
| [, step]) Oattributes: start, stop, step. |
| Returns a string containing a nicely |
| staticmethod() Convert a function to method with no self or class |
| argument. Useful for methods associated with a class that |
| do not need access to an object's internal state. |
| str(object) printablerepresentation of an object. Class overridable |
| (__str__).See also repr(). |
| super(type) Create an unbound super object. Used to call cooperative |
| superclass methods. |
| sum(sequence, Add the values in the sequence and return the sum. |
| [start]) |
| tuple(sequence) Creates a tuple with same elements as sequence. If already |
| a tuple, return itself (not a copy). |
| Returns a type object [see module types] representing |
| thetype of obj. Example: import typesif type(x) == |
| type(obj) types.StringType: print 'It is a string'NB: it is |
| recommanded to use the following form:if isinstance(x, |
| types.StringType): etc... |
| unichr(code) code. |
| unicode(string[, Creates a Unicode string from a 8-bit string, using |
| encoding[, error thegiven encoding name and error treatment ('strict', |
| ]]]) 'ignore',or 'replace'}. |
| Without arguments, returns a dictionary correspondingto the |
| current local symbol table. With a module,class or class |
| vars([object]) instance object as argumentreturns a dictionary |
| corresponding to the object'ssymbol table. Useful with "%" |
| formatting operator. |
| xrange(start [, end Like range(), but doesn't actually store entire listall at |
| [, step]]) once. Good to use in "for" loops when there is abig range |
| and little memory. |
| zip(seq1[, seq2, Returns a list of tuples where each tuple contains the nth |
| ...]) element of each of the argument sequences. |
| |
| |
| |
| |
| Built-In Exceptions |
| |
| Exception> |
| Root class for all exceptions |
| SystemExit |
| On 'sys.exit()' |
| StopIteration |
| Signal the end from iterator.next() |
| StandardError |
| Base class for all built-in exceptions; derived from Exception |
| root class. |
| ArithmeticError |
| Base class for OverflowError, ZeroDivisionError, |
| FloatingPointError |
| FloatingPointError |
| When a floating point operation fails. |
| OverflowError |
| On excessively large arithmetic operation |
| ZeroDivisionError |
| On division or modulo operation with 0 as 2nd arg |
| AssertionError |
| When an assert statement fails. |
| AttributeError |
| On attribute reference or assignment failure |
| EnvironmentError [new in 1.5.2] |
| On error outside Python; error arg tuple is (errno, errMsg...) |
| IOError [changed in 1.5.2] |
| I/O-related operation failure |
| OSError [new in 1.5.2] |
| used by the os module's os.error exception. |
| EOFError |
| Immediate end-of-file hit by input() or raw_input() |
| ImportError |
| On failure of `import' to find module or name |
| KeyboardInterrupt |
| On user entry of the interrupt key (often `Control-C') |
| LookupError |
| base class for IndexError, KeyError |
| IndexError |
| On out-of-range sequence subscript |
| KeyError |
| On reference to a non-existent mapping (dict) key |
| MemoryError |
| On recoverable memory exhaustion |
| NameError |
| On failure to find a local or global (unqualified) name |
| RuntimeError |
| Obsolete catch-all; define a suitable error instead |
| NotImplementedError [new in 1.5.2] |
| On method not implemented |
| SyntaxError |
| On parser encountering a syntax error |
| IndentationError |
| On parser encountering an indentation syntax error |
| TabError |
| On parser encountering an indentation syntax error |
| SystemError |
| On non-fatal interpreter error - bug - report it |
| TypeError |
| On passing inappropriate type to built-in op or func |
| ValueError |
| On arg error not covered by TypeError or more precise |
| Warning |
| UserWarning |
| DeprecationWarning |
| PendingDeprecationWarning |
| SyntaxWarning |
| OverflowWarning |
| RuntimeWarning |
| FutureWarning |
| |
| |
| |
| Standard methods & operators redefinition in classes |
| |
| Standard methods & operators map to special '__methods__' and thus may be |
| redefined (mostly in in user-defined classes), e.g.: |
| class x: |
| def __init__(self, v): self.value = v |
| def __add__(self, r): return self.value + r |
| a = x(3) # sort of like calling x.__init__(a, 3) |
| a + 4 # is equivalent to a.__add__(4) |
| |
| Special methods for any class |
| |
| (s: self, o: other) |
| __init__(s, args) instance initialization (on construction) |
| __del__(s) called on object demise (refcount becomes 0) |
| __repr__(s) repr() and `...` conversions |
| __str__(s) str() and 'print' statement |
| __cmp__(s, o) Compares s to o and returns <0, 0, or >0. |
| Implements >, <, == etc... |
| __hash__(s) Compute a 32 bit hash code; hash() and dictionary ops |
| __nonzero__(s) Returns False or True for truth value testing |
| __getattr__(s, name) called when attr lookup doesn't find <name> |
| __setattr__(s, name, val) called when setting an attr |
| (inside, don't use "self.name = value" |
| use "self.__dict__[name] = val") |
| __delattr__(s, name) called to delete attr <name> |
| __call__(self, *args) called when an instance is called as function. |
| |
| Operators |
| |
| See list in the operator module. Operator function names are provided with |
| 2 variants, with or without |
| ading & trailing '__' (eg. __add__ or add). |
| |
| Numeric operations special methods |
| (s: self, o: other) |
| |
| s+o = __add__(s,o) s-o = __sub__(s,o) |
| s*o = __mul__(s,o) s/o = __div__(s,o) |
| s%o = __mod__(s,o) divmod(s,o) = __divmod__(s,o) |
| s**o = __pow__(s,o) |
| s&o = __and__(s,o) |
| s^o = __xor__(s,o) s|o = __or__(s,o) |
| s<<o = __lshift__(s,o) s>>o = __rshift__(s,o) |
| nonzero(s) = __nonzero__(s) (used in boolean testing) |
| -s = __neg__(s) +s = __pos__(s) |
| abs(s) = __abs__(s) ~s = __invert__(s) (bitwise) |
| s+=o = __iadd__(s,o) s-=o = __isub__(s,o) |
| s*=o = __imul__(s,o) s/=o = __idiv__(s,o) |
| s%=o = __imod__(s,o) |
| s**=o = __ipow__(s,o) |
| s&=o = __iand__(s,o) |
| s^=o = __ixor__(s,o) s|=o = __ior__(s,o) |
| s<<=o = __ilshift__(s,o) s>>=o = __irshift__(s,o) |
| Conversions |
| int(s) = __int__(s) long(s) = __long__(s) |
| float(s) = __float__(s) complex(s) = __complex__(s) |
| oct(s) = __oct__(s) hex(s) = __hex__(s) |
| coerce(s,o) = __coerce__(s,o) |
| Right-hand-side equivalents for all binary operators exist; |
| are called when class instance is on r-h-s of operator: |
| a + 3 calls __add__(a, 3) |
| 3 + a calls __radd__(a, 3) |
| |
| All seqs and maps, general operations plus: |
| (s: self, i: index or key) |
| |
| len(s) = __len__(s) length of object, >= 0. Length 0 == false |
| s[i] = __getitem__(s,i) Element at index/key i, origin 0 |
| |
| Sequences, general methods, plus: |
| s[i]=v = __setitem__(s,i,v) |
| del s[i] = __delitem__(s,i) |
| s[i:j] = __getslice__(s,i,j) |
| s[i:j]=seq = __setslice__(s,i,j,seq) |
| del s[i:j] = __delslice__(s,i,j) == s[i:j] = [] |
| seq * n = __repeat__(seq, n) |
| s1 + s2 = __concat__(s1, s2) |
| i in s = __contains__(s, i) |
| Mappings, general methods, plus |
| hash(s) = __hash__(s) - hash value for dictionary references |
| s[k]=v = __setitem__(s,k,v) |
| del s[k] = __delitem__(s,k) |
| |
| Special informative state attributes for some types: |
| |
| Modules: |
| __doc__ (string/None, R/O): doc string (<=> __dict__['__doc__']) |
| __name__(string, R/O): module name (also in __dict__['__name__']) |
| __dict__ (dict, R/O): module's name space |
| __file__(string/undefined, R/O): pathname of .pyc, .pyo or .pyd (undef for |
| modules statically linked to the interpreter) |
| |
| Classes: [in bold: writable since 1.5.2] |
| __doc__ (string/None, R/W): doc string (<=> __dict__['__doc__']) |
| __module__ is the module name in which the class was defined |
| __name__(string, R/W): class name (also in __dict__['__name__']) |
| __bases__ (tuple, R/W): parent classes |
| __dict__ (dict, R/W): attributes (class name space) |
| |
| Instances: |
| __class__ (class, R/W): instance's class |
| __dict__ (dict, R/W): attributes |
| |
| User-defined functions: [bold: writable since 1.5.2] |
| __doc__ (string/None, R/W): doc string |
| __name__(string, R/O): function name |
| func_doc (R/W): same as __doc__ |
| func_name (R/O): same as __name__ |
| func_defaults (tuple/None, R/W): default args values if any |
| func_code (code, R/W): code object representing the compiled function body |
| func_globals (dict, R/O): ref to dictionary of func global variables |
| func_dict (dict, R/W): same as __dict__ contains the namespace supporting |
| arbitrary function attributes |
| func_closure (R/O): None or a tuple of cells that contain bindings |
| for the function's free variables. |
| |
| |
| User-defined Methods: |
| __doc__ (string/None, R/O): doc string |
| __name__(string, R/O): method name (same as im_func.__name__) |
| im_class (class, R/O): class defining the method (may be a base class) |
| im_self (instance/None, R/O): target instance object (None if unbound) |
| im_func (function, R/O): function object |
| |
| Built-in Functions & methods: |
| __doc__ (string/None, R/O): doc string |
| __name__ (string, R/O): function name |
| __self__ : [methods only] target object |
| |
| Codes: |
| co_name (string, R/O): function name |
| co_argcount (int, R/0): number of positional args |
| co_nlocals (int, R/O): number of local vars (including args) |
| co_varnames (tuple, R/O): names of local vars (starting with args) |
| co_cellvars (tuple, R/O)) the names of local variables referenced by |
| nested functions |
| co_freevars (tuple, R/O)) names of free variables |
| co_code (string, R/O): sequence of bytecode instructions |
| co_consts (tuple, R/O): litterals used by the bytecode, 1st one is |
| fct doc (or None) |
| co_names (tuple, R/O): names used by the bytecode |
| co_filename (string, R/O): filename from which the code was compiled |
| co_firstlineno (int, R/O): first line number of the function |
| co_lnotab (string, R/O): string encoding bytecode offsets to line numbers. |
| co_stacksize (int, R/O): required stack size (including local vars) |
| co_flags (int, R/O): flags for the interpreter |
| bit 2 set if fct uses "*arg" syntax |
| bit 3 set if fct uses '**keywords' syntax |
| Frames: |
| f_back (frame/None, R/O): previous stack frame (toward the caller) |
| f_code (code, R/O): code object being executed in this frame |
| f_locals (dict, R/O): local vars |
| f_globals (dict, R/O): global vars |
| f_builtins (dict, R/O): built-in (intrinsic) names |
| f_restricted (int, R/O): flag indicating whether fct is executed in |
| restricted mode |
| f_lineno (int, R/O): current line number |
| f_lasti (int, R/O): precise instruction (index into bytecode) |
| f_trace (function/None, R/W): debug hook called at start of each source line |
| f_exc_type (Type/None, R/W): Most recent exception type |
| f_exc_value (any, R/W): Most recent exception value |
| f_exc_traceback (traceback/None, R/W): Most recent exception traceback |
| Tracebacks: |
| tb_next (frame/None, R/O): next level in stack trace (toward the frame where |
| the exception occurred) |
| tb_frame (frame, R/O): execution frame of the current level |
| tb_lineno (int, R/O): line number where the exception occurred |
| tb_lasti (int, R/O): precise instruction (index into bytecode) |
| |
| Slices: |
| start (any/None, R/O): lowerbound |
| stop (any/None, R/O): upperbound |
| step (any/None, R/O): step value |
| |
| Complex numbers: |
| real (float, R/O): real part |
| imag (float, R/O): imaginary part |
| |
| |
| Important Modules |
| |
| sys |
| |
| Some sys variables |
| Variable Content |
| argv The list of command line arguments passed to aPython |
| script. sys.argv[0] is the script name. |
| builtin_module_names A list of strings giving the names of all moduleswritten |
| in C that are linked into this interpreter. |
| check_interval How often to check for thread switches or signals(measured |
| in number of virtual machine instructions) |
| exc_type, exc_value, Deprecated since release 1.5. Use exc_info() instead. |
| exc_traceback |
| exitfunc User can set to a parameterless fcn. It will getcalled |
| before interpreter exits. |
| last_type, Set only when an exception not handled andinterpreter |
| last_value, prints an error. Used by debuggers. |
| last_traceback |
| maxint maximum positive value for integers |
| modules Dictionary of modules that have already been loaded. |
| path Search path for external modules. Can be modifiedby |
| program. sys.path[0] == dir of script executing |
| platform The current platform, e.g. "sunos5", "win32" |
| ps1, ps2 prompts to use in interactive mode. |
| File objects used for I/O. One can redirect byassigning a |
| stdin, stdout, new file object to them (or any object:.with a method |
| stderr write(string) for stdout/stderr,.with a method readline() |
| for stdin) |
| version string containing version info about Python interpreter. |
| (and also: copyright, dllhandle, exec_prefix, prefix) |
| version_info tuple containing Python version info - (major, minor, |
| micro, level, serial). |
| |
| Some sys functions |
| Function Result |
| exit(n) Exits with status n. Raises SystemExit exception.(Hence can |
| be caught and ignored by program) |
| getrefcount(object Returns the reference count of the object. Generally one |
| ) higher than you might expect, because of object arg temp |
| reference. |
| setcheckinterval( Sets the interpreter's thread switching interval (in number |
| interval) of virtual code instructions, default:100). |
| settrace(func) Sets a trace function: called before each line ofcode is |
| exited. |
| setprofile(func) Sets a profile function for performance profiling. |
| Info on exception currently being handled; this is atuple |
| (exc_type, exc_value, exc_traceback).Warning: assigning the |
| exc_info() traceback return value to a loca variable in a |
| function handling an exception will cause a circular |
| reference. |
| setdefaultencoding Change default Unicode encoding - defaults to 7-bit ASCII. |
| (encoding) |
| getrecursionlimit Retrieve maximum recursion depth. |
| () |
| setrecursionlimit Set maximum recursion depth. (Defaults to 1000.) |
| () |
| |
| |
| |
| os |
| "synonym" for whatever O/S-specific module is proper for current environment. |
| this module uses posix whenever possible. |
| (see also M.A. Lemburg's utility http://www.lemburg.com/files/python/ |
| platform.py) |
| |
| Some os variables |
| Variable Meaning |
| name name of O/S-specific module (e.g. "posix", "mac", "nt") |
| path O/S-specific module for path manipulations. |
| On Unix, os.path.split() <=> posixpath.split() |
| curdir string used to represent current directory ('.') |
| pardir string used to represent parent directory ('..') |
| sep string used to separate directories ('/' or '\'). Tip: use |
| os.path.join() to build portable paths. |
| altsep Alternate sep |
| if applicable (None |
| otherwise) |
| pathsep character used to separate search path components (as in |
| $PATH), eg. ';' for windows. |
| linesep line separator as used in binary files, ie '\n' on Unix, '\ |
| r\n' on Dos/Win, '\r' |
| |
| Some os functions |
| Function Result |
| makedirs(path[, Recursive directory creation (create required intermediary |
| mode=0777]) dirs); os.error if fails. |
| removedirs(path) Recursive directory delete (delete intermediary empty |
| dirs); if fails. |
| renames(old, new) Recursive directory or file renaming; os.error if fails. |
| |
| |
| |
| posix |
| don't import this module directly, import os instead ! |
| (see also module: shutil for file copy & remove fcts) |
| |
| posix Variables |
| Variable Meaning |
| environ dictionary of environment variables, e.g.posix.environ['HOME']. |
| error exception raised on POSIX-related error. |
| Corresponding value is tuple of errno code and perror() string. |
| |
| Some posix functions |
| Function Result |
| chdir(path) Changes current directory to path. |
| chmod(path, Changes the mode of path to the numeric mode |
| mode) |
| close(fd) Closes file descriptor fd opened with posix.open. |
| _exit(n) Immediate exit, with no cleanups, no SystemExit,etc. Should use |
| this to exit a child process. |
| execv(p, args) "Become" executable p with args args |
| getcwd() Returns a string representing the current working directory |
| getpid() Returns the current process id |
| fork() Like C's fork(). Returns 0 to child, child pid to parent.[Not |
| on Windows] |
| kill(pid, Like C's kill [Not on Windows] |
| signal) |
| listdir(path) Lists (base)names of entries in directory path, excluding '.' |
| and '..' |
| lseek(fd, pos, Sets current position in file fd to position pos, expressedas |
| how) an offset relative to beginning of file (how=0), tocurrent |
| position (how=1), or to end of file (how=2) |
| mkdir(path[, Creates a directory named path with numeric mode (default 0777) |
| mode]) |
| open(file, Like C's open(). Returns file descriptor. Use file object |
| flags, mode) fctsrather than this low level ones. |
| pipe() Creates a pipe. Returns pair of file descriptors (r, w) [Not on |
| Windows]. |
| popen(command, Opens a pipe to or from command. Result is a file object to |
| mode='r', read to orwrite from, as indicated by mode being 'r' or 'w'. |
| bufSize=0) Use it to catch acommand output ('r' mode) or to feed it ('w' |
| mode). |
| remove(path) See unlink. |
| rename(src, dst Renames/moves the file or directory src to dst. [error iftarget |
| ) name already exists] |
| rmdir(path) Removes the empty directory path |
| read(fd, n) Reads n bytes from file descriptor fd and return as string. |
| Returns st_mode, st_ino, st_dev, st_nlink, st_uid,st_gid, |
| stat(path) st_size, st_atime, st_mtime, st_ctime.[st_ino, st_uid, st_gid |
| are dummy on Windows] |
| system(command) Executes string command in a subshell. Returns exitstatus of |
| subshell (usually 0 means OK). |
| Returns accumulated CPU times in sec (user, system, children's |
| times() user,children's sys, elapsed real time). [3 last not on |
| Windows] |
| unlink(path) Unlinks ("deletes") the file (not dir!) path. same as: remove |
| utime(path, ( Sets the access & modified time of the file to the given tuple |
| aTime, mTime)) of values. |
| wait() Waits for child process completion. Returns tuple ofpid, |
| exit_status [Not on Windows] |
| waitpid(pid, Waits for process pid to complete. Returns tuple ofpid, |
| options) exit_status [Not on Windows] |
| write(fd, str) Writes str to file fd. Returns nb of bytes written. |
| |
| |
| |
| posixpath |
| Do not import this module directly, import os instead and refer to this module |
| as os.path. (e.g. os.path.exists(p)) ! |
| |
| Some posixpath functions |
| Function Result |
| abspath(p) Returns absolute path for path p, taking current working dir in |
| account. |
| dirname/ |
| basename(p directory and name parts of the path p. See also split. |
| ) |
| exists(p) True if string p is an existing path (file or directory) |
| expanduser Returns string that is (a copy of) p with "~" expansion done. |
| (p) |
| expandvars Returns string that is (a copy of) p with environment vars expanded. |
| (p) [Windows: case significant; must use Unix: $var notation, not %var%] |
| getsize( return the size in bytes of filename. raise os.error. |
| filename) |
| getmtime( return last modification time of filename (integer nb of seconds |
| filename) since epoch). |
| getatime( return last access time of filename (integer nb of seconds since |
| filename) epoch). |
| isabs(p) True if string p is an absolute path. |
| isdir(p) True if string p is a directory. |
| islink(p) True if string p is a symbolic link. |
| ismount(p) True if string p is a mount point [true for all dirs on Windows]. |
| join(p[,q Joins one or more path components intelligently. |
| [,...]]) |
| Splits p into (head, tail) where tail is lastpathname component and |
| split(p) <head> is everything leadingup to that. <=> (dirname(p), basename |
| (p)) |
| splitdrive Splits path p in a pair ('drive:', tail) [Windows] |
| (p) |
| splitext(p Splits into (root, ext) where last comp of root contains no periods |
| ) and ext is empty or startswith a period. |
| Calls the function visit with arguments(arg, dirname, names) for |
| each directory recursively inthe directory tree rooted at p |
| walk(p, (including p itself if it's a dir)The argument dirname specifies the |
| visit, arg visited directory, the argumentnames lists the files in the |
| ) directory. The visit function maymodify names to influence the set |
| of directories visited belowdirname, e.g., to avoid visiting certain |
| parts of the tree. |
| |
| |
| |
| shutil |
| high-level file operations (copying, deleting). |
| |
| Main shutil functions |
| Function Result |
| copy(src, dst) Copies the contents of file src to file dst, retaining file |
| permissions. |
| copytree(src, dst Recursively copies an entire directory tree rooted at src |
| [, symlinks]) into dst (which should not already exist). If symlinks is |
| true, links insrc are kept as such in dst. |
| rmtree(path[, Deletes an entire directory tree, ignoring errors if |
| ignore_errors[, ignore_errors true,or calling onerror(func, path, |
| onerror]]) sys.exc_info()) if supplied with |
| |
| (and also: copyfile, copymode, copystat, copy2) |
| |
| time |
| |
| Variables |
| Variable Meaning |
| altzone signed offset of local DST timezone in sec west of the 0th meridian. |
| daylight nonzero if a DST timezone is specified |
| |
| Functions |
| Function Result |
| time() return a float representing UTC time in seconds since the epoch. |
| gmtime(secs), return a tuple representing time : (year aaaa, month(1-12),day |
| localtime( (1-31), hour(0-23), minute(0-59), second(0-59), weekday(0-6, 0 is |
| secs) monday), Julian day(1-366), daylight flag(-1,0 or 1)) |
| asctime( |
| timeTuple), |
| strftime( |
| format, return a formated string representing time. |
| timeTuple) |
| mktime(tuple) inverse of localtime(). Return a float. |
| strptime( parse a formated string representing time, return tuple as in |
| string[, gmtime(). |
| format]) |
| sleep(secs) Suspend execution for <secs> seconds. <secs> can be a float. |
| |
| and also: clock, ctime. |
| |
| string |
| |
| As of Python 2.0, much (though not all) of the functionality provided by the |
| string module have been superseded by built-in string methods - see Operations |
| on strings for details. |
| |
| Some string variables |
| Variable Meaning |
| digits The string '0123456789' |
| hexdigits, octdigits legal hexadecimal & octal digits |
| letters, uppercase, lowercase, Strings containing the appropriate |
| whitespace characters |
| index_error Exception raised by index() if substr not |
| found. |
| |
| Some string functions |
| Function Result |
| expandtabs(s, returns a copy of string <s> with tabs expanded. |
| tabSize) |
| find/rfind(s, sub Return the lowest/highest index in <s> where the substring |
| [, start=0[, end= <sub> is found such that <sub> is wholly contained ins |
| 0]) [start:end]. Return -1 if <sub> not found. |
| ljust/rjust/center Return a copy of string <s> left/right justified/centerd in |
| (s, width) afield of given width, padded with spaces. <s> is |
| nevertruncated. |
| lower/upper(s) Return a string that is (a copy of) <s> in lowercase/ |
| uppercase |
| split(s[, sep= Return a list containing the words of the string <s>,using |
| whitespace[, the string <sep> as a separator. |
| maxsplit=0]]) |
| join(words[, sep=' Concatenate a list or tuple of words with |
| ']) interveningseparators; inverse of split. |
| replace(s, old, Returns a copy of string <s> with all occurrences of |
| new[, maxsplit=0] substring<old> replaced by <new>. Limits to <maxsplit> |
| firstsubstitutions if specified. |
| strip(s) Return a string that is (a copy of) <s> without leadingand |
| trailing whitespace. see also lstrip, rstrip. |
| |
| |
| |
| re (sre) |
| |
| Handles Unicode strings. Implemented in new module sre, re now a mere front-end |
| for compatibility. |
| Patterns are specified as strings. Tip: Use raw strings (e.g. r'\w*') to |
| litteralize backslashes. |
| |
| |
| Regular expression syntax |
| Form Description |
| . matches any character (including newline if DOTALL flag specified) |
| ^ matches start of the string (of every line in MULTILINE mode) |
| $ matches end of the string (of every line in MULTILINE mode) |
| * 0 or more of preceding regular expression (as many as possible) |
| + 1 or more of preceding regular expression (as many as possible) |
| ? 0 or 1 occurrence of preceding regular expression |
| *?, +?, ?? Same as *, + and ? but matches as few characters as possible |
| {m,n} matches from m to n repetitions of preceding RE |
| {m,n}? idem, attempting to match as few repetitions as possible |
| [ ] defines character set: e.g. '[a-zA-Z]' to match all letters(see also |
| \w \S) |
| [^ ] defines complemented character set: matches if char is NOT in set |
| escapes special chars '*?+&$|()' and introduces special sequences |
| \ (see below). Due to Python string rules, write as '\\' orr'\' in the |
| pattern string. |
| \\ matches a litteral '\'; due to Python string rules, write as '\\\\ |
| 'in pattern string, or better using raw string: r'\\'. |
| | specifies alternative: 'foo|bar' matches 'foo' or 'bar' |
| (...) matches any RE inside (), and delimits a group. |
| (?:...) idem but doesn't delimit a group. |
| matches if ... matches next, but doesn't consume any of the string |
| (?=...) e.g. 'Isaac (?=Asimov)' matches 'Isaac' only if followed by |
| 'Asimov'. |
| (?!...) matches if ... doesn't match next. Negative of (?=...) |
| (?P<name matches any RE inside (), and delimits a named group. (e.g. r'(?P |
| >...) <id>[a-zA-Z_]\w*)' defines a group named id) |
| (?P=name) matches whatever text was matched by the earlier group named name. |
| (?#...) A comment; ignored. |
| (?letter) letter is one of 'i','L', 'm', 's', 'x'. Set the corresponding flags |
| (re.I, re.L, re.M, re.S, re.X) for the entire RE. |
| |
| Special sequences |
| Sequence Description |
| number matches content of the group of the same number; groups are numbered |
| starting from 1 |
| \A matches only at the start of the string |
| \b empty str at beg or end of word: '\bis\b' matches 'is', but not 'his' |
| \B empty str NOT at beginning or end of word |
| \d any decimal digit (<=> [0-9]) |
| \D any non-decimal digit char (<=> [^O-9]) |
| \s any whitespace char (<=> [ \t\n\r\f\v]) |
| \S any non-whitespace char (<=> [^ \t\n\r\f\v]) |
| \w any alphaNumeric char (depends on LOCALE flag) |
| \W any non-alphaNumeric char (depends on LOCALE flag) |
| \Z matches only at the end of the string |
| |
| Variables |
| Variable Meaning |
| error Exception when pattern string isn't a valid regexp. |
| |
| Functions |
| Function Result |
| Compile a RE pattern string into a regular expression object. |
| Flags (combinable by |): |
| |
| I or IGNORECASE or (?i) |
| case insensitive matching |
| compile( L or LOCALE or (?L) |
| pattern[, make \w, \W, \b, \B dependent on thecurrent locale |
| flags=0]) M or MULTILINE or (?m) |
| matches every new line and not onlystart/end of the whole |
| string |
| S or DOTALL or (?s) |
| '.' matches ALL chars, including newline |
| X or VERBOSE or (?x) |
| Ignores whitespace outside character sets |
| escape(string) return (a copy of) string with all non-alphanumerics |
| backslashed. |
| match(pattern, if 0 or more chars at beginning of <string> match the RE pattern |
| string[, flags string,return a corresponding MatchObject instance, or None if |
| ]) no match. |
| search(pattern scan thru <string> for a location matching <pattern>, return |
| , string[, acorresponding MatchObject instance, or None if no match. |
| flags]) |
| split(pattern, split <string> by occurrences of <pattern>. If capturing () are |
| string[, used inpattern, then occurrences of patterns or subpatterns are |
| maxsplit=0]) also returned. |
| findall( return a list of non-overlapping matches in <pattern>, either a |
| pattern, list ofgroups or a list of tuples if the pattern has more than 1 |
| string) group. |
| return string obtained by replacing the (<count> first) lefmost |
| sub(pattern, non-overlapping occurrences of <pattern> (a string or a RE |
| repl, string[, object) in <string>by <repl>; <repl> can be a string or a fct |
| count=0]) called with a single MatchObj arg, which must return the |
| replacement string. |
| subn(pattern, |
| repl, string[, same as sub(), but returns a tuple (newString, numberOfSubsMade) |
| count=0]) |
| |
| Regular Expression Objects |
| |
| |
| (RE objects are returned by the compile fct) |
| |
| re object attributes |
| Attribute Descrition |
| flags flags arg used when RE obj was compiled, or 0 if none provided |
| groupindex dictionary of {group name: group number} in pattern |
| pattern pattern string from which RE obj was compiled |
| |
| re object methods |
| Method Result |
| If zero or more characters at the beginning of string match this |
| regular expression, return a corresponding MatchObject instance. |
| Return None if the string does not match the pattern; note that |
| this is different from a zero-length match. |
| The optional second parameter pos gives an index in the string |
| match( where the search is to start; it defaults to 0. This is not |
| string[, completely equivalent to slicing the string; the '' pattern |
| pos][, character matches at the real beginning of the string and at |
| endpos]) positions just after a newline, but not necessarily at the index |
| where the search is to start. |
| The optional parameter endpos limits how far the string will be |
| searched; it will be as if the string is endpos characters long, so |
| only the characters from pos to endpos will be searched for a |
| match. |
| Scan through string looking for a location where this regular |
| search( expression produces a match, and return a corresponding MatchObject |
| string[, instance. Return None if no position in the string matches the |
| pos][, pattern; note that this is different from finding a zero-length |
| endpos]) match at some point in the string. |
| The optional pos and endpos parameters have the same meaning as for |
| the match() method. |
| split( |
| string[, Identical to the split() function, using the compiled pattern. |
| maxsplit= |
| 0]) |
| findall( Identical to the findall() function, using the compiled pattern. |
| string) |
| sub(repl, |
| string[, Identical to the sub() function, using the compiled pattern. |
| count=0]) |
| subn(repl, |
| string[, Identical to the subn() function, using the compiled pattern. |
| count=0]) |
| |
| Match Objects |
| |
| |
| (Match objects are returned by the match & search functions) |
| |
| Match object attributes |
| Attribute Description |
| pos value of pos passed to search or match functions; index intostring at |
| which RE engine started search. |
| endpos value of endpos passed to search or match functions; index intostring |
| beyond which RE engine won't go. |
| re RE object whose match or search fct produced this MatchObj instance |
| string string passed to match() or search() |
| |
| Match object functions |
| Function Result |
| returns one or more groups of the match. If one arg, result is a |
| group([g1 string;if multiple args, result is a tuple with one item per arg. If |
| , g2, gi is 0,return value is entire matching string; if 1 <= gi <= 99, |
| ...]) returnstring matching group #gi (or None if no such group); gi may |
| also bea group name. |
| returns a tuple of all groups of the match; groups not |
| groups() participatingto the match have a value of None. Returns a string |
| instead of tupleif len(tuple)=1 |
| start( |
| group), returns indices of start & end of substring matched by group (or |
| end(group Noneif group exists but doesn't contribute to the match) |
| ) |
| span( returns the 2-tuple (start(group), end(group)); can be (None, None)if |
| group) group didn't contibute to the match. |
| |
| |
| |
| math |
| |
| Variables: |
| pi |
| e |
| Functions (see ordinary C man pages for info): |
| acos(x) |
| asin(x) |
| atan(x) |
| atan2(x, y) |
| ceil(x) |
| cos(x) |
| cosh(x) |
| degrees(x) |
| exp(x) |
| fabs(x) |
| floor(x) |
| fmod(x, y) |
| frexp(x) -- Unlike C: (float, int) = frexp(float) |
| ldexp(x, y) |
| log(x [,base]) |
| log10(x) |
| modf(x) -- Unlike C: (float, float) = modf(float) |
| pow(x, y) |
| radians(x) |
| sin(x) |
| sinh(x) |
| sqrt(x) |
| tan(x) |
| tanh(x) |
| |
| getopt |
| |
| Functions: |
| getopt(list, optstr) -- Similar to C. <optstr> is option |
| letters to look for. Put ':' after letter |
| if option takes arg. E.g. |
| # invocation was "python test.py -c hi -a arg1 arg2" |
| opts, args = getopt.getopt(sys.argv[1:], 'ab:c:') |
| # opts would be |
| [('-c', 'hi'), ('-a', '')] |
| # args would be |
| ['arg1', 'arg2'] |
| |
| |
| List of modules and packages in base distribution |
| |
| (built-ins and content of python Lib directory) |
| (Python NT distribution, may be slightly different in other distributions) |
| |
| Standard library modules |
| Operation Result |
| aifc Stuff to parse AIFF-C and AIFF files. |
| anydbm Generic interface to all dbm clones. (dbhash, gdbm, |
| dbm,dumbdbm) |
| asynchat Support for 'chat' style protocols |
| asyncore Asynchronous File I/O (in select style) |
| atexit Register functions to be called at exit of Python interpreter. |
| audiodev Audio support for a few platforms. |
| base64 Conversions to/from base64 RFC-MIME transport encoding . |
| BaseHTTPServer Base class forhttp services. |
| Bastion "Bastionification" utility (control access to instance vars) |
| bdb A generic Python debugger base class. |
| binhex Macintosh binhex compression/decompression. |
| bisect List bisection algorithms. |
| bz2 Support for bz2 compression/decompression. |
| calendar Calendar printing functions. |
| cgi Wraps the WWW Forms Common Gateway Interface (CGI). |
| cgitb Utility for handling CGI tracebacks. |
| CGIHTTPServer CGI http services. |
| cmd A generic class to build line-oriented command interpreters. |
| datetime Basic date and time types. |
| code Utilities needed to emulate Python's interactive interpreter |
| codecs Lookup existing Unicode encodings and register new ones. |
| colorsys Conversion functions between RGB and other color systems. |
| commands Tools for executing UNIX commands . |
| compileall Force "compilation" of all .py files in a directory. |
| ConfigParser Configuration file parser (much like windows .ini files) |
| copy Generic shallow and deep copying operations. |
| copy_reg Helper to provide extensibility for pickle/cPickle. |
| csv Read and write files with comma separated values. |
| dbhash (g)dbm-compatible interface to bsdhash.hashopen. |
| dircache Sorted list of files in a dir, using a cache. |
| [DEL:dircmp:DEL] [DEL:Defines a class to build directory diff tools on.:DEL] |
| difflib Tool for creating delta between sequences. |
| dis Bytecode disassembler. |
| distutils Package installation system. |
| doctest Tool for running and verifying tests inside doc strings. |
| dospath Common operations on DOS pathnames. |
| dumbdbm A dumb and slow but simple dbm clone. |
| [DEL:dump:DEL] [DEL:Print python code that reconstructs a variable.:DEL] |
| email Comprehensive support for internet email. |
| exceptions Class based built-in exception hierarchy. |
| filecmp File comparison. |
| fileinput Helper class to quickly write a loop over all standard input |
| files. |
| [DEL:find:DEL] [DEL:Find files directory hierarchy matching a pattern.:DEL] |
| fnmatch Filename matching with shell patterns. |
| formatter A test formatter. |
| fpformat General floating point formatting functions. |
| ftplib An FTP client class. Based on RFC 959. |
| gc Perform garbacge collection, obtain GC debug stats, and tune |
| GC parameters. |
| getopt Standard command line processing. See also ftp:// |
| www.pauahtun.org/pub/getargspy.zip |
| getpass Utilities to get a password and/or the current user name. |
| glob filename globbing. |
| gopherlib Gopher protocol client interface. |
| [DEL:grep:DEL] [DEL:'grep' utilities.:DEL] |
| gzip Read & write gzipped files. |
| heapq Priority queue implemented using lists organized as heaps. |
| HMAC Keyed-Hashing for Message Authentication -- RFC 2104. |
| htmlentitydefs Proposed entity definitions for HTML. |
| htmllib HTML parsing utilities. |
| HTMLParser A parser for HTML and XHTML. |
| httplib HTTP client class. |
| ihooks Hooks into the "import" mechanism. |
| imaplib IMAP4 client.Based on RFC 2060. |
| imghdr Recognizing image files based on their first few bytes. |
| imputil Privides a way of writing customised import hooks. |
| inspect Tool for probing live Python objects. |
| keyword List of Python keywords. |
| knee A Python re-implementation of hierarchical module import. |
| linecache Cache lines from files. |
| linuxaudiodev Lunix /dev/audio support. |
| locale Support for number formatting using the current locale |
| settings. |
| logging Python logging facility. |
| macpath Pathname (or related) operations for the Macintosh. |
| macurl2path Mac specific module for conversion between pathnames and URLs. |
| mailbox A class to handle a unix-style or mmdf-style mailbox. |
| mailcap Mailcap file handling (RFC 1524). |
| mhlib MH (mailbox) interface. |
| mimetools Various tools used by MIME-reading or MIME-writing programs. |
| mimetypes Guess the MIME type of a file. |
| MimeWriter Generic MIME writer. |
| mimify Mimification and unmimification of mail messages. |
| mmap Interface to memory-mapped files - they behave like mutable |
| strings./font> |
| multifile Class to make multi-file messages easier to handle. |
| mutex Mutual exclusion -- for use with module sched. |
| netrc |
| nntplib An NNTP client class. Based on RFC 977. |
| ntpath Common operations on DOS pathnames. |
| nturl2path Mac specific module for conversion between pathnames and URLs. |
| optparse A comprehensive tool for processing command line options. |
| os Either mac, dos or posix depending system. |
| [DEL:packmail: [DEL:Create a self-unpacking shell archive.:DEL] |
| DEL] |
| pdb A Python debugger. |
| pickle Pickling (save and restore) of Python objects (a faster |
| Cimplementation exists in built-in module: cPickle). |
| pipes Conversion pipeline templates. |
| pkgunil Utilities for working with Python packages. |
| popen2 variations on pipe open. |
| poplib A POP3 client class. Based on the J. Myers POP3 draft. |
| posixfile Extended (posix) file operations. |
| posixpath Common operations on POSIX pathnames. |
| pprint Support to pretty-print lists, tuples, & dictionaries |
| recursively. |
| profile Class for profiling python code. |
| pstats Class for printing reports on profiled python code. |
| pydoc Utility for generating documentation from source files. |
| pty Pseudo terminal utilities. |
| pyexpat Interface to the Expay XML parser. |
| py_compile Routine to "compile" a .py file to a .pyc file. |
| pyclbr Parse a Python file and retrieve classes and methods. |
| Queue A multi-producer, multi-consumer queue. |
| quopri Conversions to/from quoted-printable transport encoding. |
| rand Don't use unless you want compatibility with C's rand(). |
| random Random variable generators |
| re Regular Expressions. |
| reconvert Convert old ("regex") regular expressions to new syntax |
| ("re"). |
| repr Redo repr() but with limits on most sizes. |
| rexec Restricted execution facilities ("safe" exec, eval, etc). |
| rfc822 RFC-822 message manipulation class. |
| rlcompleter Word completion for GNU readline 2.0. |
| robotparser Parse robots.txt files, useful for web spiders. |
| sched A generally useful event scheduler class. |
| sets Module for a set datatype. |
| sgmllib A parser for SGML. |
| shelve Manage shelves of pickled objects. |
| shlex Lexical analyzer class for simple shell-like syntaxes. |
| shutil Utility functions usable in a shell-like program. |
| SimpleHTTPServer Simple extension to base http class |
| site Append module search paths for third-party packages to |
| sys.path. |
| smtplib SMTP Client class (RFC 821) |
| sndhdr Several routines that help recognizing sound. |
| SocketServer Generic socket server classes. |
| stat Constants and functions for interpreting stat/lstat struct. |
| statcache Maintain a cache of file stats. |
| statvfs Constants for interpreting statvfs struct as returned by |
| os.statvfs()and os.fstatvfs() (if they exist). |
| string A collection of string operations. |
| StringIO File-like objects that read/write a string buffer (a fasterC |
| implementation exists in built-in module: cStringIO). |
| sunau Stuff to parse Sun and NeXT audio files. |
| sunaudio Interpret sun audio headers. |
| symbol Non-terminal symbols of Python grammar (from "graminit.h"). |
| tabnanny,/font> Check Python source for ambiguous indentation. |
| tarfile Facility for reading and writing to the *nix tarfile format. |
| telnetlib TELNET client class. Based on RFC 854. |
| tempfile Temporary file name allocation. |
| textwrap Object for wrapping and filling text. |
| threading Proposed new higher-level threading interfaces |
| threading_api (doc of the threading module) |
| toaiff Convert "arbitrary" sound files to AIFF files . |
| token Tokens (from "token.h"). |
| tokenize Compiles a regular expression that recognizes Python tokens. |
| traceback Format and print Python stack traces. |
| tty Terminal utilities. |
| turtle LogoMation-like turtle graphics |
| types Define names for all type symbols in the std interpreter. |
| tzparse Parse a timezone specification. |
| unicodedata Interface to unicode properties. |
| urllib Open an arbitrary URL. |
| urlparse Parse URLs according to latest draft of standard. |
| user Hook to allow user-specified customization code to run. |
| UserDict A wrapper to allow subclassing of built-in dict class. |
| UserList A wrapper to allow subclassing of built-in list class. |
| UserString A wrapper to allow subclassing of built-in string class. |
| [DEL:util:DEL] [DEL:some useful functions that don't fit elsewhere !!:DEL] |
| uu UUencode/UUdecode. |
| unittest Utilities for implementing unit testing. |
| wave Stuff to parse WAVE files. |
| weakref Tools for creating and managing weakly referenced objects. |
| webbrowser Platform independent URL launcher. |
| [DEL:whatsound: [DEL:Several routines that help recognizing sound files.:DEL] |
| DEL] |
| whichdb Guess which db package to use to open a db file. |
| xdrlib Implements (a subset of) Sun XDR (eXternal Data |
| Representation) |
| xmllib A parser for XML, using the derived class as static DTD. |
| xml.dom Classes for processing XML using the Document Object Model. |
| xml.sax Classes for processing XML using the SAX API. |
| xmlrpclib Support for remote procedure calls using XML. |
| zipfile Read & write PK zipped files. |
| [DEL:zmod:DEL] [DEL:Demonstration of abstruse mathematical concepts.:DEL] |
| |
| |
| |
| * Built-ins * |
| |
| sys Interpreter state vars and functions |
| __built-in__ Access to all built-in python identifiers |
| __main__ Scope of the interpreters main program, script or stdin |
| array Obj efficiently representing arrays of basic values |
| math Math functions of C standard |
| time Time-related functions (also the newer datetime module) |
| regex Regular expression matching operations |
| marshal Read and write some python values in binary format |
| struct Convert between python values and C structs |
| |
| * Standard * |
| |
| getopt Parse cmd line args in sys.argv. A la UNIX 'getopt'. |
| os A more portable interface to OS dependent functionality |
| re Functions useful for working with regular expressions |
| string Useful string and characters functions and exceptions |
| random Mersenne Twister pseudo-random number generator |
| thread Low-level primitives for working with process threads |
| threading idem, new recommanded interface. |
| |
| * Unix/Posix * |
| |
| dbm Interface to Unix ndbm database library |
| grp Interface to Unix group database |
| posix OS functionality standardized by C and POSIX standards |
| posixpath POSIX pathname functions |
| pwd Access to the Unix password database |
| select Access to Unix select multiplex file synchronization |
| socket Access to BSD socket interface |
| |
| * Tk User-interface Toolkit * |
| |
| tkinter Main interface to Tk |
| |
| * Multimedia * |
| |
| audioop Useful operations on sound fragments |
| imageop Useful operations on images |
| jpeg Access to jpeg image compressor and decompressor |
| rgbimg Access SGI imglib image files |
| |
| * Cryptographic Extensions * |
| |
| md5 Interface to RSA's MD5 message digest algorithm |
| sha Interface to the SHA message digest algorithm |
| HMAC Keyed-Hashing for Message Authentication -- RFC 2104. |
| |
| * Stdwin * Standard Window System |
| |
| stdwin Standard Window System interface |
| stdwinevents Stdwin event, command, and selection constants |
| rect Rectangle manipulation operations |
| |
| * SGI IRIX * (4 & 5) |
| |
| al SGI audio facilities |
| AL al constants |
| fl Interface to FORMS library |
| FL fl constants |
| flp Functions for form designer |
| fm Access to font manager library |
| gl Access to graphics library |
| GL Constants for gl |
| DEVICE More constants for gl |
| imgfile Imglib image file interface |
| |
| * Suns * |
| |
| sunaudiodev Access to sun audio interface |
| |
| |
| Workspace exploration and idiom hints |
| |
| dir(<module>) list functions, variables in <module> |
| dir() get object keys, defaults to local name space |
| if __name__ == '__main__': main() invoke main if running as script |
| map(None, lst1, lst2, ...) merge lists |
| b = a[:] create copy of seq structure |
| _ in interactive mode, is last value printed |
| |
| |
| |
| |
| |
| |
| |
| Python Mode for Emacs |
| |
| (Not revised, possibly not up to date) |
| Type C-c ? when in python-mode for extensive help. |
| INDENTATION |
| Primarily for entering new code: |
| TAB indent line appropriately |
| LFD insert newline, then indent |
| DEL reduce indentation, or delete single character |
| Primarily for reindenting existing code: |
| C-c : guess py-indent-offset from file content; change locally |
| C-u C-c : ditto, but change globally |
| C-c TAB reindent region to match its context |
| C-c < shift region left by py-indent-offset |
| C-c > shift region right by py-indent-offset |
| MARKING & MANIPULATING REGIONS OF CODE |
| C-c C-b mark block of lines |
| M-C-h mark smallest enclosing def |
| C-u M-C-h mark smallest enclosing class |
| C-c # comment out region of code |
| C-u C-c # uncomment region of code |
| MOVING POINT |
| C-c C-p move to statement preceding point |
| C-c C-n move to statement following point |
| C-c C-u move up to start of current block |
| M-C-a move to start of def |
| C-u M-C-a move to start of class |
| M-C-e move to end of def |
| C-u M-C-e move to end of class |
| EXECUTING PYTHON CODE |
| C-c C-c sends the entire buffer to the Python interpreter |
| C-c | sends the current region |
| C-c ! starts a Python interpreter window; this will be used by |
| subsequent C-c C-c or C-c | commands |
| C-c C-w runs PyChecker |
| |
| VARIABLES |
| py-indent-offset indentation increment |
| py-block-comment-prefix comment string used by py-comment-region |
| py-python-command shell command to invoke Python interpreter |
| py-scroll-process-buffer t means always scroll Python process buffer |
| py-temp-directory directory used for temp files (if needed) |
| py-beep-if-tab-change ring the bell if tab-width is changed |
| |
| |
| The Python Debugger |
| |
| (Not revised, possibly not up to date, see 1.5.2 Library Ref section 9.1; in 1.5.2, you may also use debugger integrated in IDLE) |
| |
| Accessing |
| |
| import pdb (it's a module written in Python) |
| -- defines functions : |
| run(statement[,globals[, locals]]) |
| -- execute statement string under debugger control, with optional |
| global & local environment. |
| runeval(expression[,globals[, locals]]) |
| -- same as run, but evaluate expression and return value. |
| runcall(function[, argument, ...]) |
| -- run function object with given arg(s) |
| pm() -- run postmortem on last exception (like debugging a core file) |
| post_mortem(t) |
| -- run postmortem on traceback object <t> |
| |
| -- defines class Pdb : |
| use Pdb to create reusable debugger objects. Object |
| preserves state (i.e. break points) between calls. |
| |
| runs until a breakpoint hit, exception, or end of program |
| If exception, variable '__exception__' holds (exception,value). |
| |
| Commands |
| |
| h, help |
| brief reminder of commands |
| b, break [<arg>] |
| if <arg> numeric, break at line <arg> in current file |
| if <arg> is function object, break on entry to fcn <arg> |
| if no arg, list breakpoints |
| cl, clear [<arg>] |
| if <arg> numeric, clear breakpoint at <arg> in current file |
| if no arg, clear all breakpoints after confirmation |
| w, where |
| print current call stack |
| u, up |
| move up one stack frame (to top-level caller) |
| d, down |
| move down one stack frame |
| s, step |
| advance one line in the program, stepping into calls |
| n, next |
| advance one line, stepping over calls |
| r, return |
| continue execution until current function returns |
| (return value is saved in variable "__return__", which |
| can be printed or manipulated from debugger) |
| c, continue |
| continue until next breakpoint |
| j, jump lineno |
| Set the next line that will be executed |
| a, args |
| print args to current function |
| rv, retval |
| prints return value from last function that returned |
| p, print <arg> |
| prints value of <arg> in current stack frame |
| l, list [<first> [, <last>]] |
| List source code for the current file. |
| Without arguments, list 11 lines around the current line |
| or continue the previous listing. |
| With one argument, list 11 lines starting at that line. |
| With two arguments, list the given range; |
| if the second argument is less than the first, it is a count. |
| whatis <arg> |
| prints type of <arg> |
| ! |
| executes rest of line as a Python statement in the current stack frame |
| q quit |
| immediately stop execution and leave debugger |
| <return> |
| executes last command again |
| Any input debugger doesn't recognize as a command is assumed to be a |
| Python statement to execute in the current stack frame, the same way |
| the exclamation mark ("!") command does. |
| |
| Example |
| |
| (1394) python |
| Python 1.0.3 (Sep 26 1994) |
| Copyright 1991-1994 Stichting Mathematisch Centrum, Amsterdam |
| >>> import rm |
| >>> rm.run() |
| Traceback (innermost last): |
| File "<stdin>", line 1 |
| File "./rm.py", line 7 |
| x = div(3) |
| File "./rm.py", line 2 |
| return a / r |
| ZeroDivisionError: integer division or modulo |
| >>> import pdb |
| >>> pdb.pm() |
| > ./rm.py(2)div: return a / r |
| (Pdb) list |
| 1 def div(a): |
| 2 -> return a / r |
| 3 |
| 4 def run(): |
| 5 global r |
| 6 r = 0 |
| 7 x = div(3) |
| 8 print x |
| [EOF] |
| (Pdb) print r |
| 0 |
| (Pdb) q |
| >>> pdb.runcall(rm.run) |
| etc. |
| |
| Quirks |
| |
| Breakpoints are stored as filename, line number tuples. If a module is reloaded |
| after editing, any remembered breakpoints are likely to be wrong. |
| |
| Always single-steps through top-most stack frame. That is, "c" acts like "n". |
| |
| |