[Python-Dev] Re: Prospective Peephole Transformation
python at rcn.com
Fri Feb 18 16:15:04 CET 2005
> > Raymond then
> > for x in [1,2,3]:
> > to
> > for x in frozenset([1,2,3]):
That's not right. for-statements are not touched.
> I may be missing something here (didn't follow the whole thread) but
> those two are not functionally equal.
> The docstring on frozenset sais "Build an immutable unordered
> So there's no guarantee that the elements will return from the
> frozenset iterator in the order that you constructed the frozenset
Only contains expressions are translated:
"if x in [1,2,3]"
currently turns into:
"if x in (1,2,3)"
and I'm proposing that it go one step further:
"if x in Seachset([1,2,3])"
where Search set is a frozenset subtype that doesn't require x to be
hashable. Also, the transformation would only happen when the contents
of the search are all constants.
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