diff options
Diffstat (limited to 'Doc/ref/ref3.tex')
| -rw-r--r-- | Doc/ref/ref3.tex | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex index d8cf888..66aa273 100644 --- a/Doc/ref/ref3.tex +++ b/Doc/ref/ref3.tex @@ -977,10 +977,8 @@ level a traceback object is inserted in front of the current traceback. When an exception handler is entered, the stack trace is made available to the program. (See section~\ref{try}, ``The \code{try} statement.'') -It is accessible as \code{sys.exc_traceback}, and also as the third -item of the tuple returned by \code{sys.exc_info()}. The latter is -the preferred interface, since it works correctly when the program is -using multiple threads. +It is accessible as the third +item of the tuple returned by \code{sys.exc_info()}. When the program contains no suitable handler, the stack trace is written (nicely formatted) to the standard error stream; if the interpreter is interactive, it is also made available to the user as @@ -994,7 +992,6 @@ interactive, it is also made available to the user as \ttindex{exc_traceback} \ttindex{last_traceback}} \ttindex{sys.exc_info} -\ttindex{sys.exc_traceback} \ttindex{sys.last_traceback} Special read-only attributes: \member{tb_next} is the next level in the @@ -1198,13 +1195,13 @@ reference count of an object from going to zero include: circular references between objects (e.g., a doubly-linked list or a tree data structure with parent and child pointers); a reference to the object on the stack frame of a function that caught an exception (the -traceback stored in \code{sys.exc_traceback} keeps the stack frame +traceback stored in \code{sys.exc_info()[2]} keeps the stack frame alive); or a reference to the object on the stack frame that raised an unhandled exception in interactive mode (the traceback stored in \code{sys.last_traceback} keeps the stack frame alive). The first situation can only be remedied by explicitly breaking the cycles; the latter two situations can be resolved by storing \code{None} in -\code{sys.exc_traceback} or \code{sys.last_traceback}. Circular +\code{sys.last_traceback}. Circular references which are garbage are detected when the option cycle detector is enabled (it's on by default), but can only be cleaned up if there are no Python-level \method{__del__()} methods involved. |