[Python-ideas] Enums

[Robert Kern]

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