[Python-Dev] Inconsistent API for sets.Set and build-in set

[Barry Warsaw]

I've been looking at the API for sets.Set and built-in set objects in
Python 2.4.1 and I think I have found some minor inconsistencies.

Background: we have an object that is very similar to "sets" and we
originally modeled the API after sets.Set since we started with Python
2.3.  Now I'm trying to update the API so that it's consistent with
Python 2.4's built-in set object and I've noticed the following
discrepancies.

set.Set has both an .update() method and a .union_update() method.  They
appear to be completely identical, accepting either a Set object or an
arbitrary sequence.  This is the case despite the docstring difference
for these two methods and the fact that Set.update() isn't documented on
the texinfo page.

Built-in set has only .update() though but it acts just like the set.Set
methods above.  Note that of all these methods, only Set.update() is
documented to take an iterable argument.

These inconsistencies could prove a bit problematic when porting Py2.3
applications using sets.Set to Py2.4 using built-in set.  I'd like to
fix this for Python 2.4.2, and I think the changes are pretty minimal.

If there are no objections, I propose to do the following (only in
Python 2.4 and 2.5):

      * Add set.union_update() as an alias for set.update().
      * Add to docstrings for all methods that 't' can be any iterable.
      * Update texinfo documentation to add Set.update() and
        set.union_update() and explain that all can take iterables

I consider this a bug in 2.4, not a new feature, because without it, it
makes more work in porting applications.

Thoughts?

I'm willing to Just Fix It, but if someone wants to see a patch first,
I'll be happy to generate it and post it to SF.

-Barry

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