On 7/25/11 4:39 PM, Michael Foord wrote:
On 25 July 2011 21:47, Robert Kern <robert.kern@gmail.com <mailto:robert.kern@gmail.com>> wrote:
On 7/25/11 1:43 PM, Michael Foord wrote:
Some apis (for example those exported directly from C) can't work with something that isn't a real int.
I think almost all of those will usually accept an object that implements __int__ and __index__, don't they? E.g.
[~] |1> import os
[~] |2> class A(object): ..> def __init__(self,x): ..> self.x = x ..> def __int__(self): ..> return self.x ..> def __index__(self): ..> return self.x ..>
[~] |10> os.open('foo', A(os.O_RDWR)) 21
os.open() just uses PyArg_ParseTuple(), like most extension functions. I'm sure you could write an extension function that would reject A() instances, but it's more work, so most people don't.
Providing __index__ may indeed be enough.
From experiment with os.open() under 2.7 and 3.1, it is not enough, though perhaps either PyArg_ParseTuple() or PyInt_As*() should be modified to make it so. -- Robert Kern "I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth." -- Umberto Eco