Merge lost revisions back
diff --git a/Doc/ref/ref6.tex b/Doc/ref/ref6.tex
index 086d49b..b1d4572 100644
--- a/Doc/ref/ref6.tex
+++ b/Doc/ref/ref6.tex
@@ -27,14 +27,14 @@
Expression statements are used (mostly interactively) to compute and
write a value, or (usually) to call a procedure (a function that
returns no meaningful result; in Python, procedures return the value
-\verb\None\):
+\verb@None@):
\begin{verbatim}
expression_stmt: expression_list
\end{verbatim}
An expression statement evaluates the expression list (which may be a
-single expression). If the value is not \verb\None\, it is converted
+single expression). If the value is not \verb@None@, it is converted
to a string using the rules for string conversions (expressions in
reverse quotes), and the resulting string is written to standard
output (see section \ref{print}) on a line by itself.
@@ -45,9 +45,9 @@
\indexii{standard}{output}
\indexii{writing}{values}
-(The exception for \verb\None\ is made so that procedure calls, which
+(The exception for \verb@None@ is made so that procedure calls, which
are syntactically equivalent to expressions, do not cause any output.
-A tuple with only \verb\None\ items is written normally.)
+A tuple with only \verb@None@ items is written normally.)
\indexii{procedure}{call}
\section{Assignment statements}
@@ -114,7 +114,7 @@
\begin{itemize}
\item
-If the name does not occur in a \verb\global\ statement in the current
+If the name does not occur in a \verb@global@ statement in the current
code block: the name is bound to the object in the current local name
space.
\stindex{global}
@@ -140,10 +140,10 @@
\item
If the target is an attribute reference: The primary expression in the
reference is evaluated. It should yield an object with assignable
-attributes; if this is not the case, \verb\TypeError\ is raised. That
+attributes; if this is not the case, \verb@TypeError@ is raised. That
object is then asked to assign the assigned object to the given
attribute; if it cannot perform the assignment, it raises an exception
-(usually but not necessarily \verb\AttributeError\).
+(usually but not necessarily \verb@AttributeError@).
\indexii{attribute}{assignment}
\item
@@ -159,7 +159,7 @@
is added to it. The resulting value must be a nonnegative integer
less than the sequence's length, and the sequence is asked to assign
the assigned object to its item with that index. If the index is out
-of range, \verb\IndexError\ is raised (assignment to a subscripted
+of range, \verb@IndexError@ is raised (assignment to a subscripted
sequence cannot add new items to a list).
\obindex{sequence}
\obindex{list}
@@ -175,16 +175,17 @@
\item
If the target is a slicing: The primary expression in the reference is
-evaluated. It should yield a mutable sequence (list) object. The
+evaluated. It should yield a mutable sequence object (e.g. a list). The
assigned object should be a sequence object of the same type. Next,
the lower and upper bound expressions are evaluated, insofar they are
present; defaults are zero and the sequence's length. The bounds
should evaluate to (small) integers. If either bound is negative, the
sequence's length is added to it. The resulting bounds are clipped to
lie between zero and the sequence's length, inclusive. Finally, the
-sequence object is asked to replace the items indicated by the slice
-with the items of the assigned sequence. This may change the
-sequence's length, if it allows it.
+sequence object is asked to replace the slice with the items of the
+assigned sequence. The length of the slice may be different from the
+length of the assigned sequence, thus changing the length of the
+target sequence, if the object allows it.
\indexii{slicing}{assignment}
\end{itemize}
@@ -201,7 +202,7 @@
pass_stmt: "pass"
\end{verbatim}
-\verb\pass\ is a null operation --- when it is executed, nothing
+\verb@pass@ is a null operation --- when it is executed, nothing
happens. It is useful as a placeholder when a statement is
required syntactically, but no code needs to be executed, for example:
\indexii{null}{operation}
@@ -230,7 +231,7 @@
Deletion of a name removes the binding of that name (which must exist)
from the local or global name space, depending on whether the name
-occurs in a \verb\global\ statement in the same code block.
+occurs in a \verb@global@ statement in the same code block.
\stindex{global}
\indexii{unbinding}{name}
@@ -247,7 +248,7 @@
print_stmt: "print" [ condition ("," condition)* [","] ]
\end{verbatim}
-\verb\print\ evaluates each condition in turn and writes the resulting
+\verb@print@ evaluates each condition in turn and writes the resulting
object to standard output (see below). If an object is not a string,
it is first converted to a string using the rules for string
conversions. The (resulting or original) string is then written. A
@@ -256,21 +257,21 @@
line. This is the case: (1) when no characters have yet been written
to standard output; or (2) when the last character written to standard
output is \verb/\n/; or (3) when the last write operation on standard
-output was not a \verb\print\ statement. (In some cases it may be
+output was not a \verb@print@ statement. (In some cases it may be
functional to write an empty string to standard output for this
reason.)
\index{output}
\indexii{writing}{values}
-A \verb/"\n"/ character is written at the end, unless the \verb\print\
+A \verb/"\n"/ character is written at the end, unless the \verb@print@
statement ends with a comma. This is the only action if the statement
-contains just the keyword \verb\print\.
+contains just the keyword \verb@print@.
\indexii{trailing}{comma}
\indexii{newline}{suppression}
-Standard output is defined as the file object named \verb\stdout\
-in the built-in module \verb\sys\. If no such object exists,
-or if it is not a writable file, a \verb\RuntimeError\ exception is raised.
+Standard output is defined as the file object named \verb@stdout@
+in the built-in module \verb@sys@. If no such object exists,
+or if it is not a writable file, a \verb@RuntimeError@ exception is raised.
(The original implementation attempts to write to the system's original
standard output instead, but this is not safe, and should be fixed.)
\indexii{standard}{output}
@@ -285,19 +286,19 @@
return_stmt: "return" [condition_list]
\end{verbatim}
-\verb\return\ may only occur syntactically nested in a function
+\verb@return@ may only occur syntactically nested in a function
definition, not within a nested class definition.
\indexii{function}{definition}
\indexii{class}{definition}
-If a condition list is present, it is evaluated, else \verb\None\
+If a condition list is present, it is evaluated, else \verb@None@
is substituted.
-\verb\return\ leaves the current function call with the condition
-list (or \verb\None\) as return value.
+\verb@return@ leaves the current function call with the condition
+list (or \verb@None@) as return value.
-When \verb\return\ passes control out of a \verb\try\ statement
-with a \verb\finally\ clause, that finally clause is executed
+When \verb@return@ passes control out of a \verb@try@ statement
+with a \verb@finally@ clause, that finally clause is executed
before really leaving the function.
\kwindex{finally}
@@ -308,14 +309,14 @@
raise_stmt: "raise" condition ["," condition]
\end{verbatim}
-\verb\raise\ evaluates its first condition, which must yield
+\verb@raise@ evaluates its first condition, which must yield
a string object. If there is a second condition, this is evaluated,
-else \verb\None\ is substituted.
+else \verb@None@ is substituted.
\index{exception}
\indexii{raising}{exception}
It then raises the exception identified by the first object,
-with the second one (or \verb\None\) as its parameter.
+with the second one (or \verb@None@) as its parameter.
\section{The {\tt break} statement}
\stindex{break}
@@ -324,22 +325,23 @@
break_stmt: "break"
\end{verbatim}
-\verb\break\ may only occur syntactically nested in a \verb\for\
-or \verb\while\ loop, not nested in a function or class definition.
+\verb@break@ may only occur syntactically nested in a \verb@for@
+or \verb@while@ loop, but not nested in a function or class definition
+within that loop.
\stindex{for}
\stindex{while}
\indexii{loop}{statement}
-It terminates the neares enclosing loop, skipping the optional
-\verb\else\ clause if the loop has one.
+It terminates the nearest enclosing loop, skipping the optional
+\verb@else@ clause if the loop has one.
\kwindex{else}
-If a \verb\for\ loop is terminated by \verb\break\, the loop control
+If a \verb@for@ loop is terminated by \verb@break@, the loop control
target keeps its current value.
\indexii{loop control}{target}
-When \verb\break\ passes control out of a \verb\try\ statement
-with a \verb\finally\ clause, that finally clause is executed
+When \verb@break@ passes control out of a \verb@try@ statement
+with a \verb@finally@ clause, that finally clause is executed
before really leaving the loop.
\kwindex{finally}
@@ -350,11 +352,10 @@
continue_stmt: "continue"
\end{verbatim}
-\verb\continue\ may only occur syntactically nested in a \verb\for\ or
-\verb\while\ loop, not nested in a function or class definition, and
-not nested in the \verb\try\ clause of a \verb\try\ statement with a
-\verb\finally\ clause (it may occur nested in a \verb\except\ or
-\verb\finally\ clause of a \verb\try\ statement though).
+\verb@continue@ may only occur syntactically nested in a \verb@for@ or
+\verb@while@ loop, but not nested in a function or class definition or
+\verb@try@ statement within that loop.\footnote{Except that it may
+currently occur within an \verb@except@ clause.}
\stindex{for}
\stindex{while}
\indexii{loop}{statement}
@@ -373,9 +374,9 @@
Import statements are executed in two steps: (1) find a module, and
initialize it if necessary; (2) define a name or names in the local
-name space (of the scope where the \verb\import\ statement occurs).
-The first form (without \verb\from\) repeats these steps for each
-identifier in the list, the \verb\from\ form performs them once, with
+name space (of the scope where the \verb@import@ statement occurs).
+The first form (without \verb@from@) repeats these steps for each
+identifier in the list, the \verb@from@ form performs them once, with
the first identifier specifying the module name.
\indexii{importing}{module}
\indexii{name}{binding}
@@ -383,15 +384,15 @@
The system maintains a table of modules that have been initialized,
indexed by module name. (The current implementation makes this table
-accessible as \verb\sys.modules\.) When a module name is found in
+accessible as \verb@sys.modules@.) When a module name is found in
this table, step (1) is finished. If not, a search for a module
definition is started. This first looks for a built-in module
definition, and if no built-in module if the given name is found, it
searches a user-specified list of directories for a file whose name is
-the module name with extension \verb\".py"\. (The current
-implementation uses the list of strings \verb\sys.path\ as the search
+the module name with extension \verb@".py"@. (The current
+implementation uses the list of strings \verb@sys.path@ as the search
path; it is initialized from the shell environment variable
-\verb\$PYTHONPATH\, with an installation-dependent default.)
+\verb@$PYTHONPATH@, with an installation-dependent default.)
\ttindex{modules}
\ttindex{sys.modules}
\indexii{module}{name}
@@ -404,9 +405,9 @@
If a built-in module is found, its built-in initialization code is
executed and step (1) is finished. If no matching file is found,
-\verb\ImportError\ is raised. If a file is found, it is parsed,
+\verb@ImportError@ is raised. If a file is found, it is parsed,
yielding an executable code block. If a syntax error occurs,
-\verb\SyntaxError\ is raised. Otherwise, an empty module of the given
+\verb@SyntaxError@ is raised. Otherwise, an empty module of the given
name is created and inserted in the module table, and then the code
block is executed in the context of this module. Exceptions during
this execution terminate step (1).
@@ -418,23 +419,23 @@
When step (1) finishes without raising an exception, step (2) can
begin.
-The first form of \verb\import\ statement binds the module name in the
+The first form of \verb@import@ statement binds the module name in the
local name space to the module object, and then goes on to import the
-next identifier, if any. The \verb\from\ from does not bind the
+next identifier, if any. The \verb@from@ from does not bind the
module name: it goes through the list of identifiers, looks each one
of them up in the module found in step (1), and binds the name in the
local name space to the object thus found. If a name is not found,
-\verb\ImportError\ is raised. If the list of identifiers is replaced
-by a star (\verb\*\), all names defined in the module are bound,
-except those beginning with an underscore(\verb\_\).
+\verb@ImportError@ is raised. If the list of identifiers is replaced
+by a star (\verb@*@), all names defined in the module are bound,
+except those beginning with an underscore(\verb@_@).
\indexii{name}{binding}
\exindex{ImportError}
-Names bound by import statements may not occur in \verb\global\
+Names bound by import statements may not occur in \verb@global@
statements in the same scope.
\stindex{global}
-The \verb\from\ form with \verb\*\ may only occur in a module scope.
+The \verb@from@ form with \verb@*@ may only occur in a module scope.
\kwindex{from}
\ttindex{from ... import *}
@@ -450,19 +451,19 @@
global_stmt: "global" identifier ("," identifier)*
\end{verbatim}
-The \verb\global\ statement is a declaration which holds for the
+The \verb@global@ statement is a declaration which holds for the
entire current scope. It means that the listed identifiers are to be
interpreted as globals. While {\em using} global names is automatic
if they are not defined in the local scope, {\em assigning} to global
-names would be impossible without \verb\global\.
+names would be impossible without \verb@global@.
\indexiii{global}{name}{binding}
-Names listed in a \verb\global\ statement must not be used in the same
-scope before that \verb\global\ statement is executed.
+Names listed in a \verb@global@ statement must not be used in the same
+scope before that \verb@global@ statement is executed.
-Names listed in a \verb\global\ statement must not be defined as formal
-parameters or in a \verb\for\ loop control target, \verb\class\
-definition, function definition, or \verb\import\ statement.
+Names listed in a \verb@global@ statement must not be defined as formal
+parameters or in a \verb@for@ loop control target, \verb@class@
+definition, function definition, or \verb@import@ statement.
(The current implementation does not enforce the latter two
restrictions, but programs should not abuse this freedom, as future
@@ -478,7 +479,7 @@
This statement will be used in the future to control access to
instance and class variables. Currently its syntax and effects are
-undefined; however the keyword \verb\access\ is a reserved word for
+undefined; however the keyword \verb@access@ is a reserved word for
the parser.
\section{The {\tt exec} statement} \label{exec}
@@ -496,12 +497,12 @@
executed. If it is a code object, it is simply executed.
In all cases, if the optional parts are omitted, the code is executed
-in the current scope. If only the first expression after \verb\in\ is
+in the current scope. If only the first expression after \verb@in@ is
specified, it should be a dictionary, which will be used for both the
global and the local variables. If two expressions are given, both
must be dictionaries and they are used for the global and local
variables, respectively.
Note: dynamic evaluation of expressions is supported by the built-in
-function \verb\eval\.
+function \verb@eval@.