Override 'and' and 'or'

[Bruno Desthuilliers]

Dekker a écrit :
> Is it possible to override 'and' and/or 'or'? I cannot find a special
> method for it... __and__ and __rand__ and __or__ and __ror__ are for
> binary manipulation... any proposals?

http://docs.python.org/ref/customization.html
"""
__nonzero__(  	self)
     Called to implement truth value testing, and the built-in operation 
bool(); should return False or True, or their integer equivalents 0 or 
1. When this method is not defined, __len__() is called, if it is 
defined (see below). If a class defines neither __len__() nor 
__nonzero__(), all its instances are considered true.
"""

Not that in Python, 'and' don't yield bools:

 >>> "aa" and "bb"
'bb'
 >>> "aa" and None # yields None
 >>> "aa" and 0
0
 >>> "aa" or "bb"
'aa'
 >>> 0 or "bb"
'bb'
 >>> None or "bb"
'bb'
 >>> "aa" or 0
'aa'
 >>> "aa" or None
'aa'
 >>>

HTH