diff options
| -rw-r--r-- | Doc/ref/ref7.tex | 40 | ||||
| -rw-r--r-- | Misc/NEWS | 2 |
2 files changed, 22 insertions, 20 deletions
diff --git a/Doc/ref/ref7.tex b/Doc/ref/ref7.tex index 535ed95..cfafc74 100644 --- a/Doc/ref/ref7.tex +++ b/Doc/ref/ref7.tex @@ -195,26 +195,25 @@ The \keyword{try} statement specifies exception handlers and/or cleanup code for a group of statements: \begin{productionlist} - \production{try_stmt} - {\token{try_exc_stmt} | \token{try_fin_stmt}} - \production{try_exc_stmt} + \production{try_stmt} {try1_stmt | try2_stmt} + \production{try1_stmt} {"try" ":" \token{suite}} \productioncont{("except" [\token{expression} ["," \token{target}]] ":" \token{suite})+} \productioncont{["else" ":" \token{suite}]} - \production{try_fin_stmt} - {"try" ":" \token{suite} - "finally" ":" \token{suite}} + \productioncont{["finally" ":" \token{suite}]} + \production{try2_stmt} + {"try" ":" \token{suite}} + \productioncont{"finally" ":" \token{suite}} \end{productionlist} -There are two forms of \keyword{try} statement: -\keyword{try}...\keyword{except} and -\keyword{try}...\keyword{finally}. These forms cannot be mixed (but -they can be nested in each other). +\versionchanged[In previous versions of Python, +\keyword{try}...\keyword{except}...\keyword{finally} did not work. +\keyword{try}...\keyword{except} had to be nested in +\keyword{try}...\keyword{finally}]{2.5} -The \keyword{try}...\keyword{except} form specifies one or more -exception handlers -(the \keyword{except} clauses). When no exception occurs in the +The \keyword{except} clause(s) specify one or more exception handlers. +When no exception occurs in the \keyword{try} clause, no exception handler is executed. When an exception occurs in the \keyword{try} suite, a search for an exception handler is started. This search inspects the except clauses in turn until @@ -232,6 +231,8 @@ string object, not just a string with the same value). If no except clause matches the exception, the search for an exception handler continues in the surrounding code and on the invocation stack. +\footnote{The exception is propogated to the invocation stack only if +there is no \keyword{finally} clause that negates the exception.} If the evaluation of an expression in the header of an except clause raises an exception, the original search for a handler is canceled @@ -277,12 +278,13 @@ preceding \keyword{except} clauses. \stindex{break} \stindex{continue} -The \keyword{try}...\keyword{finally} form specifies a `cleanup' handler. The -\keyword{try} clause is executed. When no exception occurs, the -\keyword{finally} clause is executed. When an exception occurs in the -\keyword{try} clause, the exception is temporarily saved, the -\keyword{finally} clause is executed, and then the saved exception is -re-raised. If the \keyword{finally} clause raises another exception or +If \keyword{finally} is present, it specifies a `cleanup' handler. The +\keyword{try} clause is executed, including any \keyword{except} and +\keyword{else} clauses. If an exception occurs in any of the clauses +and is not handled, the exception is temporarily saved. The +\keyword{finally} clause is executed. If there is a saved exception, +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 @@ -14,7 +14,7 @@ Core and builtins - Implementation of PEP 341 - Unification of try/except and try/finally. "except" clauses can now be written together with a "finally" clause in - one try statement instead of two nested ones. + one try statement instead of two nested ones. Patch #1355913. - Bug #1379994: Builtin unicode_escape and raw_unicode_escape codec now encodes backslash correctly. |