On 2021-06-21 12:26 p.m., Stephen J. Turnbull wrote: > Soni L. writes: > > > The trick to extension methods is that they're only available when you > > explicitly use them. > > What does "explicitly use them" mean? How does this help avoid the > kinds of problems we know that monkey-patching causes?
Monkey-patching: ```py mod1.py import foo foo.Bar.monkeymethod = ... ``` ```py mod2.py import foo foo.Bar.monkeymethod = ... ``` "Extension methods": ```py mod1.py import foo def __getattr__(o, attr): if isinstance(o, foo.Bar) and attr == "monkeymethod": return ... return getattr(o, attr) ``` ```py mod2.py import foo def __getattr__(o, attr): if isinstance(o, foo.Bar) and attr == "monkeymethod": return ... return getattr(o, attr) ``` Note how the former changes foo.Bar, whereas the latter only changes the module's own __getattr__. You can't have conflicts with the latter. (Also note that this "module's own __getattr__" doesn't provide extension methods by itself, but can be used as a mechanism to implement extension methods.) _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/RD5LKZUBBDAUH7UUMCRY6HUYZHPSKFQH/ Code of Conduct: http://python.org/psf/codeofconduct/
