[Python-Dev] Possible patch for functools partial (original) (raw)

Michael Foord fuzzyman at voidspace.org.uk
Fri May 7 20:01:46 CEST 2010

On 07/05/2010 19:57, Steve Holden wrote:

Steven D'Aprano wrote:

On Sat, 8 May 2010 02:07:55 am Rob Cliffe wrote:

Sorry to grouse, but isn't this maybe being a bit too clever? Using your example, p1 = partial(operator.add) is creating a callable, p1, i.e. a sort of function. Yes I know technically it's not a function, but it behaves very much like one.

Now, if I write def f1(x,y): return x+y def f2(x,y): return x+y I don't expect f1==f2 to be True, even though f1 and f2 behave in exactly the same way, and indeed it is not. I do expect f1==f2, and I'm (mildly) disappointed that they're not. How about def f1(x, y): return x+y def f2(x, y): return y+x As you know, there are limits to everything. It seems to me that while pure mathematics can (sometime) easily determine functional equivalence, once you get to code it's a lot harder because there are semantic constraints that don't apply in pure mathematics. Sure, but in CPython at least you could detect identical functions (but not functions that do the same thing in a different way). All the information is exposed - it would mean comparing bytecode though (plus signature etc) and is not likely to be portable to other implementations.

Partials that wrap the same function (based on identity) comparing equal seems useful enough to me.

Michael

-- http://www.ironpythoninaction.com/

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