[Python-ideas] Enums

Mon Jul 25 22:47:24 CEST 2011

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.
-- 
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