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Re-word the explanation of the in/not in operators for increased content 

and clarity.

Add a footnote to the information on the possibility of shadowing builtins
with locals & module globals.
This commit is contained in:
Fred Drake 2001-03-06 07:32:11 +00:00
parent ce7129ea4e
commit ac79e95167
1 changed files with 14 additions and 6 deletions
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20
Doc/ref/ref5.tex
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@ -65,7 +65,12 @@ block (even in unreachable code), and is not mentioned in a
name throughout that code block. When it is not assigned to anywhere
in the block, or when it is assigned to but also explicitly listed in
a \keyword{global} statement, it refers to a global name if one exists,
else to a built-in name (and this binding may dynamically change).
else to a built-in name (and this binding may dynamically
change).\footnote{The Python interpreter provides a useful set of
predefined built-in functions. It is not recommended to reuse
(hide) these names with self defined objects. See the
\citetitle[../lib/built-in-funcs.html]{Python Library Reference} for
the descriptions of built-in functions and methods.}
\indexii{name}{binding}
\index{code block}
\stindex{global}
@ -757,13 +762,16 @@ execution of a program.
\end{itemize}
The operators \keyword{in} and \keyword{not in} test for set
membership: every type can define membership in whatever way is
appropriate. Traditionally, this interface has been tightly bound to
the sequence interface, which is related in that presence in a sequence
can be usefully interpreted as membership in a set.
membership. \code{\var{x} in \var{s}} evaluates to true if \var{x}
is a member of the set \var{s}, and false otherwise. \code{\var{x}
not in \var{s}} returns the negation of \code{\var{x} in \var{s}}.
The set membership test has traditionally been bound to sequences; an
object is a member of a set if the set is a sequence and contains an
element equal to that object. However, it is possible for an object
to support membership tests without being a sequence.
For the list and tuple types, \code{\var{x} in \var{y}} is true if and
only if there exists such an index \var{i} such that
only if there exists an index \var{i} such that
\code{\var{x} == \var{y}[\var{i}]} is true.
For the Unicode and string types, \code{\var{x} in \var{y}} is true if