[Python-Dev] PyDict_SetItem hook

Collin Winter collinw at gmail.com
Thu Apr 2 02:31:29 CEST 2009

On Wed, Apr 1, 2009 at 4:29 PM, John Ehresman <jpe at wingware.com> wrote:
> I've written a proof of concept patch to add a hook to PyDict_SetItem at
>  http://bugs.python.org/issue5654  My motivation is to enable watchpoints in
> a python debugger that are called when an attribute or global changes.  I
> know that this won't cover function locals and objects with slots (as Martin
> pointed out).
> We talked about this at the sprints and a few issues came up:
> * Is this worth it for debugger watchpoint support?  This is a feature that
> probably wouldn't be used regularly but is extremely useful in some
> situations.
> * Would it be better to create a namespace dict subclass of dict, use it for
> modules, classes, & instances, and only allow watches of the subclass
> instances?
> * To what extent should non-debugger code use the hook?  At one end of the
> spectrum, the hook could be made readily available for non-debug use and at
> the other end, it could be documented as being debug only, disabled in
> python -O, & not exposed in the stdlib to python code.

Have you measured the impact on performance?


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