Added doc strings and reindented according to new standard, without tabs.
(Like ntpath.py, this was contributed by "Charles G. Waldman" <cgw@pgt.com>)
diff --git a/Lib/posixpath.py b/Lib/posixpath.py
index 9960801..1166881 100644
--- a/Lib/posixpath.py
+++ b/Lib/posixpath.py
@@ -5,6 +5,10 @@
# on other systems (e.g. Mac, Windows), os.path provides the same
# operations in a manner specific to that platform, and is an alias
# to another module (e.g. macpath, ntpath).
+"""Common pathname manipulations, Posix version.
+Instead of importing this module
+directly, import os and refer to this module as os.path.
+"""
import os
import stat
@@ -16,14 +20,16 @@
# (another function should be defined to do that).
def normcase(s):
- return s
+ """Normalize case of pathname. Has no effect under Posix"""
+ return s
# Return wheter a path is absolute.
# Trivial in Posix, harder on the Mac or MS-DOS.
def isabs(s):
- return s[:1] == '/'
+ """Test whether a path is absolute"""
+ return s[:1] == '/'
# Join pathnames.
@@ -31,15 +37,16 @@
# Insert a '/' unless the first part is empty or already ends in '/'.
def join(a, *p):
- path = a
- for b in p:
- if b[:1] == '/':
- path = b
- elif path == '' or path[-1:] == '/':
- path = path + b
- else:
- path = path + '/' + b
- return path
+ """Join two or more pathname components, inserting '/' as needed"""
+ path = a
+ for b in p:
+ if b[:1] == '/':
+ path = b
+ elif path == '' or path[-1:] == '/':
+ path = path + b
+ else:
+ path = path + '/' + b
+ return path
# Split a path in head (everything up to the last '/') and tail (the
@@ -48,13 +55,15 @@
# Trailing '/'es are stripped from head unless it is the root.
def split(p):
- import string
- i = string.rfind(p, '/') + 1
- head, tail = p[:i], p[i:]
- if head and head <> '/'*len(head):
- while head[-1] == '/':
- head = head[:-1]
- return head, tail
+ """Split a pathname. Returns tuple "(head, tail)" where "tail" is
+everything after the final slash. Either part may be empty"""
+ import string
+ i = string.rfind(p, '/') + 1
+ head, tail = p[:i], p[i:]
+ if head and head <> '/'*len(head):
+ while head[-1] == '/':
+ head = head[:-1]
+ return head, tail
# Split a path in root and extension.
@@ -63,75 +72,84 @@
# It is always true that root + ext == p.
def splitext(p):
- root, ext = '', ''
- for c in p:
- if c == '/':
- root, ext = root + ext + c, ''
- elif c == '.':
- if ext:
- root, ext = root + ext, c
- else:
- ext = c
- elif ext:
- ext = ext + c
- else:
- root = root + c
- return root, ext
+ """Split the extension from a pathname. Extension is everything from the
+last dot to the end. Returns "(root, ext)", either part may be empty"""
+ root, ext = '', ''
+ for c in p:
+ if c == '/':
+ root, ext = root + ext + c, ''
+ elif c == '.':
+ if ext:
+ root, ext = root + ext, c
+ else:
+ ext = c
+ elif ext:
+ ext = ext + c
+ else:
+ root = root + c
+ return root, ext
# Split a pathname into a drive specification and the rest of the
# path. Useful on DOS/Windows/NT; on Unix, the drive is always empty.
def splitdrive(p):
- return '', p
+ """Split a pathname into drive and path. On Posix, drive is always
+empty"""
+ return '', p
# Return the tail (basename) part of a path.
def basename(p):
- return split(p)[1]
+ """Returns the final component of a pathname"""
+ return split(p)[1]
# Return the head (dirname) part of a path.
def dirname(p):
- return split(p)[0]
+ """Returns the directory component of a pathname"""
+ return split(p)[0]
# Return the longest prefix of all list elements.
def commonprefix(m):
- if not m: return ''
- prefix = m[0]
- for item in m:
- for i in range(len(prefix)):
- if prefix[:i+1] <> item[:i+1]:
- prefix = prefix[:i]
- if i == 0: return ''
- break
- return prefix
+ "Given a list of pathnames, returns the longest common leading component"
+ if not m: return ''
+ prefix = m[0]
+ for item in m:
+ for i in range(len(prefix)):
+ if prefix[:i+1] <> item[:i+1]:
+ prefix = prefix[:i]
+ if i == 0: return ''
+ break
+ return prefix
# Is a path a symbolic link?
# This will always return false on systems where os.lstat doesn't exist.
def islink(path):
- try:
- st = os.lstat(path)
- except (os.error, AttributeError):
- return 0
- return stat.S_ISLNK(st[stat.ST_MODE])
+ """Test whether a path is a symbolic link"""
+ try:
+ st = os.lstat(path)
+ except (os.error, AttributeError):
+ return 0
+ return stat.S_ISLNK(st[stat.ST_MODE])
# Does a path exist?
# This is false for dangling symbolic links.
def exists(path):
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return 1
+ """Test whether a path exists. Returns false for broken symbolic links"""
+ try:
+ st = os.stat(path)
+ except os.error:
+ return 0
+ return 1
# Is a path a directory?
@@ -139,11 +157,12 @@
# for the same path.
def isdir(path):
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return stat.S_ISDIR(st[stat.ST_MODE])
+ """Test whether a path is a directory"""
+ try:
+ st = os.stat(path)
+ except os.error:
+ return 0
+ return stat.S_ISDIR(st[stat.ST_MODE])
# Is a path a regular file?
@@ -151,78 +170,87 @@
# for the same path.
def isfile(path):
- try:
- st = os.stat(path)
- except os.error:
- return 0
- return stat.S_ISREG(st[stat.ST_MODE])
+ """Test whether a path is a regular file"""
+ try:
+ st = os.stat(path)
+ except os.error:
+ return 0
+ return stat.S_ISREG(st[stat.ST_MODE])
# Are two filenames really pointing to the same file?
def samefile(f1, f2):
- s1 = os.stat(f1)
- s2 = os.stat(f2)
- return samestat(s1, s2)
+ """Test whether two pathnames reference the same actual file"""
+ s1 = os.stat(f1)
+ s2 = os.stat(f2)
+ return samestat(s1, s2)
# Are two open files really referencing the same file?
# (Not necessarily the same file descriptor!)
def sameopenfile(fp1, fp2):
- s1 = os.fstat(fp1)
- s2 = os.fstat(fp2)
- return samestat(s1, s2)
+ """Test whether two open file objects reference the same file"""
+ s1 = os.fstat(fp1)
+ s2 = os.fstat(fp2)
+ return samestat(s1, s2)
# Are two stat buffers (obtained from stat, fstat or lstat)
# describing the same file?
def samestat(s1, s2):
- return s1[stat.ST_INO] == s2[stat.ST_INO] and \
- s1[stat.ST_DEV] == s2[stat.ST_DEV]
+ """Test whether two stat buffers reference the same file"""
+ return s1[stat.ST_INO] == s2[stat.ST_INO] and \
+ s1[stat.ST_DEV] == s2[stat.ST_DEV]
# Is a path a mount point?
# (Does this work for all UNIXes? Is it even guaranteed to work by Posix?)
def ismount(path):
- try:
- s1 = os.stat(path)
- s2 = os.stat(join(path, '..'))
- except os.error:
- return 0 # It doesn't exist -- so not a mount point :-)
- dev1 = s1[stat.ST_DEV]
- dev2 = s2[stat.ST_DEV]
- if dev1 != dev2:
- return 1 # path/.. on a different device as path
- ino1 = s1[stat.ST_INO]
- ino2 = s2[stat.ST_INO]
- if ino1 == ino2:
- return 1 # path/.. is the same i-node as path
- return 0
+ """Test whether a path is a mount point"""
+ try:
+ s1 = os.stat(path)
+ s2 = os.stat(join(path, '..'))
+ except os.error:
+ return 0 # It doesn't exist -- so not a mount point :-)
+ dev1 = s1[stat.ST_DEV]
+ dev2 = s2[stat.ST_DEV]
+ if dev1 != dev2:
+ return 1 # path/.. on a different device as path
+ ino1 = s1[stat.ST_INO]
+ ino2 = s2[stat.ST_INO]
+ if ino1 == ino2:
+ return 1 # path/.. is the same i-node as path
+ return 0
# Directory tree walk.
# For each directory under top (including top itself, but excluding
# '.' and '..'), func(arg, dirname, filenames) is called, where
# dirname is the name of the directory and filenames is the list
-# files files (and subdirectories etc.) in the directory.
+# of files (and subdirectories etc.) in the directory.
# The func may modify the filenames list, to implement a filter,
# or to impose a different order of visiting.
def walk(top, func, arg):
- try:
- names = os.listdir(top)
- except os.error:
- return
- func(arg, top, names)
- exceptions = ('.', '..')
- for name in names:
- if name not in exceptions:
- name = join(top, name)
- if isdir(name) and not islink(name):
- walk(name, func, arg)
+ """walk(top,func,args) calls func(arg, d, files) for each directory "d"
+in the tree rooted at "top" (including "top" itself). "files" is a list
+of all the files and subdirs in directory "d".
+"""
+ try:
+ names = os.listdir(top)
+ except os.error:
+ return
+ func(arg, top, names)
+ exceptions = ('.', '..')
+ for name in names:
+ if name not in exceptions:
+ name = join(top, name)
+ if isdir(name) and not islink(name):
+ walk(name, func, arg)
# Expand paths beginning with '~' or '~user'.
@@ -235,24 +263,26 @@
# variable expansion.)
def expanduser(path):
- if path[:1] <> '~':
- return path
- i, n = 1, len(path)
- while i < n and path[i] <> '/':
- i = i+1
- if i == 1:
- if not os.environ.has_key('HOME'):
- return path
- userhome = os.environ['HOME']
- else:
- import pwd
- try:
- pwent = pwd.getpwnam(path[1:i])
- except KeyError:
- return path
- userhome = pwent[5]
- if userhome[-1:] == '/': i = i+1
- return userhome + path[i:]
+ """Expand ~ and ~user constructions. If user or $HOME is unknown,
+do nothing"""
+ if path[:1] <> '~':
+ return path
+ i, n = 1, len(path)
+ while i < n and path[i] <> '/':
+ i = i+1
+ if i == 1:
+ if not os.environ.has_key('HOME'):
+ return path
+ userhome = os.environ['HOME']
+ else:
+ import pwd
+ try:
+ pwent = pwd.getpwnam(path[1:i])
+ except KeyError:
+ return path
+ userhome = pwent[5]
+ if userhome[-1:] == '/': i = i+1
+ return userhome + path[i:]
# Expand paths containing shell variable substitutions.
@@ -262,29 +292,31 @@
_varprog = None
def expandvars(path):
- global _varprog
- if '$' not in path:
- return path
- if not _varprog:
- import re
- _varprog = re.compile(r'\$(\w+|\{[^}]*\})')
- i = 0
- while 1:
- m = _varprog.search(path, i)
- if not m:
- break
- i, j = m.span(0)
- name = m.group(1)
- if name[:1] == '{' and name[-1:] == '}':
- name = name[1:-1]
- if os.environ.has_key(name):
- tail = path[j:]
- path = path[:i] + os.environ[name]
- i = len(path)
- path = path + tail
- else:
- i = j
- return path
+ """Expand shell variables of form $var and ${var}. Unknown variables
+are left unchanged"""
+ global _varprog
+ if '$' not in path:
+ return path
+ if not _varprog:
+ import re
+ _varprog = re.compile(r'\$(\w+|\{[^}]*\})')
+ i = 0
+ while 1:
+ m = _varprog.search(path, i)
+ if not m:
+ break
+ i, j = m.span(0)
+ name = m.group(1)
+ if name[:1] == '{' and name[-1:] == '}':
+ name = name[1:-1]
+ if os.environ.has_key(name):
+ tail = path[j:]
+ path = path[:i] + os.environ[name]
+ i = len(path)
+ path = path + tail
+ else:
+ i = j
+ return path
# Normalize a path, e.g. A//B, A/./B and A/foo/../B all become A/B.
@@ -292,26 +324,26 @@
# if it contains symbolic links!
def normpath(path):
- import string
- # Treat initial slashes specially
- slashes = ''
- while path[:1] == '/':
- slashes = slashes + '/'
- path = path[1:]
- comps = string.splitfields(path, '/')
- i = 0
- while i < len(comps):
- if comps[i] == '.':
- del comps[i]
- elif comps[i] == '..' and i > 0 and \
- comps[i-1] not in ('', '..'):
- del comps[i-1:i+1]
- i = i-1
- elif comps[i] == '' and i > 0 and comps[i-1] <> '':
- del comps[i]
- else:
- i = i+1
- # If the path is now empty, substitute '.'
- if not comps and not slashes:
- comps.append('.')
- return slashes + string.joinfields(comps, '/')
+ """Normalize path, eliminating double slashes, etc."""
+ import string
+ # Treat initial slashes specially
+ slashes = ''
+ while path[:1] == '/':
+ slashes = slashes + '/'
+ path = path[1:]
+ comps = string.splitfields(path, '/')
+ i = 0
+ while i < len(comps):
+ if comps[i] == '.':
+ del comps[i]
+ elif comps[i] == '..' and i > 0 and comps[i-1] not in ('', '..'):
+ del comps[i-1:i+1]
+ i = i-1
+ elif comps[i] == '' and i > 0 and comps[i-1] <> '':
+ del comps[i]
+ else:
+ i = i+1
+ # If the path is now empty, substitute '.'
+ if not comps and not slashes:
+ comps.append('.')
+ return slashes + string.joinfields(comps, '/')