SF patch #1303595: improve description of __builtins__, explaining how it

varies between __main__ and other modules, and strongly suggest not touching
it but using __builtin__ if absolutely necessary
This commit is contained in:
Fred Drake 2006-06-10 20:01:34 +00:00
parent 5114826950
commit 5e30626f7f
1 changed files with 14 additions and 4 deletions

View File

@ -97,10 +97,20 @@ searched. The global statement must precede all uses of the name.
The built-in namespace associated with the execution of a code block
is actually found by looking up the name \code{__builtins__} in its
global namespace; this should be a dictionary or a module (in the
latter case the module's dictionary is used). Normally, the
\code{__builtins__} namespace is the dictionary of the built-in module
\module{__builtin__} (note: no `s'). If it isn't, restricted
execution\indexii{restricted}{execution} mode is in effect.
latter case the module's dictionary is used). By default, when in the
\module{__main__} module, \code{__builtins__} is the built-in module
\module{__builtin__} (note: no `s'); when in any other module,
\code{__builtins__} is an alias for the dictionary of the
\module{__builtin__} module itself. \code{__builtins__} can be set
to a user-created dictionary to create a weak form of restricted
execution\indexii{restricted}{execution}.
\begin{notice}
Users should not touch \code{__builtins__}; it is strictly an
implementation detail. Users wanting to override values in the
built-in namespace should \keyword{import} the \module{__builtin__}
(no `s') module and modify its attributes appropriately.
\end{notice}
The namespace for a module is automatically created the first time a
module is imported. The main module for a script is always called