Roy Smith wrote:
> In article <[EMAIL PROTECTED]>,
> "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote:
>
>
>>You can even get closer, but it is NOT recommended
>>
>>class foostr(str):
>> def plural (self):
>> if self.value[-1] in "sz":
>> return self.value + "es"
>> else:
>> return self.value + "s"
>>
>>
>>#ugly hack
>>setattr(__builtins__, "str", foostr)
>>
>>print str("apple").plural()
>>
>># this however does not work
>># print "apple".plural()
>
>
> It's fascinating that the setattr() works (and I agree with you that it's a
> bad idea), but given that it does work, why doesn't it work with a string
> literal?
Because the string literal is the *actual* C-level builtin string type,
not whatever type happens to be in __builtins__.str at the time. ("At
the time" is also a tricky proposition - string literals are made into
obects at compile time, before __builtins__ is twiddled with.)
BTW, on setattr():
'''
setattr( object, name, value)
This is the counterpart of getattr(). The arguments are an object, a
string and an arbitrary value. The string may name an existing attribute
or a new attribute. The function assigns the value to the attribute,
provided the object allows it. For example, setattr(x, 'foobar', 123) is
equivalent to x.foobar = 123.
'''
i.e. '''setattr(__builtins__, "str", foostr)''' is the same as
'''__builtins__.str = foostr''', but I would agree that the setattr
gives more of a "black magic" warning.
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