diff options
Diffstat (limited to 'Doc')
| -rw-r--r-- | Doc/ref/ref3.tex | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/Doc/ref/ref3.tex b/Doc/ref/ref3.tex index edd9d10..4ef4905 100644 --- a/Doc/ref/ref3.tex +++ b/Doc/ref/ref3.tex @@ -925,7 +925,8 @@ reference is deleted. It is not guaranteed that the interpreter exits. \stindex{del} -\strong{Programmer's note:} \samp{del x} doesn't directly call +\begin{notice} +\samp{del x} doesn't directly call \code{x.__del__()} --- the former decrements the reference count for \code{x} by one, and the latter is only called when its reference count reaches zero. Some common situations that may prevent the @@ -938,13 +939,22 @@ 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 None in -\code{sys.exc_traceback} or \code{sys.last_traceback}. - -\warning{Due to the precarious circumstances under which +latter two situations can be resolved by storing \code{None} in +\code{sys.exc_traceback} or \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. +Refer to the documentation for the \ulink{\module{gc} +module}{../lib/module-gc.html} for more information about how +\method{__del__()} methods are handled by the cycle detector, +particularly the description of the \code{garbage} value. +\end{notice} + +\begin{notice}[warning] +Due to the precarious circumstances under which \method{__del__()} methods are invoked, exceptions that occur during their execution are ignored, and a warning is printed to \code{sys.stderr} -instead. Also, when \method{__del__()} is invoked is response to a module +instead. Also, when \method{__del__()} is invoked in response to a module being deleted (e.g., when execution of the program is done), other globals referenced by the \method{__del__()} method may already have been deleted. For this reason, \method{__del__()} methods should do the @@ -953,7 +963,8 @@ guarantees that globals whose name begins with a single underscore are deleted from their module before other globals are deleted; if no other references to such globals exist, this may help in assuring that imported modules are still available at the time when the -\method{__del__()} method is called.} +\method{__del__()} method is called. +\end{notice} \end{methoddesc} \begin{methoddesc}[object]{__repr__}{self} |