diff options
Diffstat (limited to 'Doc/ref/ref7.tex')
| -rw-r--r-- | Doc/ref/ref7.tex | 27 |
1 files changed, 10 insertions, 17 deletions
diff --git a/Doc/ref/ref7.tex b/Doc/ref/ref7.tex index a2d46a8d70..6bc0b08257 100644 --- a/Doc/ref/ref7.tex +++ b/Doc/ref/ref7.tex @@ -281,11 +281,8 @@ and is not handled, the exception is temporarily saved. The it is re-raised at the end of the \keyword{finally} clause. If the \keyword{finally} clause raises another exception or executes a \keyword{return} or \keyword{break} statement, the saved -exception is lost. A \keyword{continue} statement is illegal in the -\keyword{finally} clause. (The reason is a problem with the current -implementation -- this restriction may be lifted in the future). The -exception information is not available to the program during execution of -the \keyword{finally} clause. +exception is lost. The exception information is not available to the +program during execution of the \keyword{finally} clause. \kwindex{finally} When a \keyword{return}, \keyword{break} or \keyword{continue} statement is @@ -312,38 +309,34 @@ The \keyword{with} statement is used to wrap the execution of a block with methods defined by a context manager (see section~\ref{context-managers}). This allows common \keyword{try}...\keyword{except}...\keyword{finally} usage patterns to -be encapsulated as context managers for convenient reuse. +be encapsulated for convenient reuse. \begin{productionlist} \production{with_stmt} - {"with" \token{expression} ["as" target_list] ":" \token{suite}} + {"with" \token{expression} ["as" target] ":" \token{suite}} \end{productionlist} The execution of the \keyword{with} statement proceeds as follows: \begin{enumerate} -\item The expression is evaluated, to obtain a context manager -object. +\item The context expression is evaluated to obtain a context manager. -\item The context manager's \method{__context__()} method is invoked to -obtain a context object. +\item The context manager's \method{__enter__()} method is invoked. -\item The context object's \method{__enter__()} method is invoked. - -\item If a target list was included in the \keyword{with} +\item If a target was included in the \keyword{with} statement, the return value from \method{__enter__()} is assigned to it. \note{The \keyword{with} statement guarantees that if the \method{__enter__()} method returns without an error, then \method{__exit__()} will always be called. Thus, if an error occurs during the assignment to the target list, it will be treated the same as -an error occurring within the suite would be. See step 6 below.} +an error occurring within the suite would be. See step 5 below.} \item The suite is executed. -\item The context object's \method{__exit__()} method is invoked. If an -exception caused the suite to be exited, its type, value, and +\item The context manager's \method{__exit__()} method is invoked. If +an exception caused the suite to be exited, its type, value, and traceback are passed as arguments to \method{__exit__()}. Otherwise, three \constant{None} arguments are supplied. |