Return type of operator on inherited class

Diez B. Roggisch deets at nospam.web.de
Mon Mar 5 12:55:45 CET 2007


looping wrote:

> Hi,
> my question is on this example:
> 
> class MyStr(str):
>     def hello(self):
>         print 'Hello !'
> 
> s1 = MyStr('My string')
> s2 = MyStr('My second string')
> 
> s1.hello()
> s2.hello()
> 
> s = s1 + s2
> 
> s.hello()
> 
>>>>
> Hello !
> Hello !
> Traceback (most recent call last):
>   File "<string>", line 204, in run_nodebug
>   File "<module1>", line 13, in <module>
> AttributeError: 'str' object has no attribute 'hello'
> 
> How could I get a type MyStr from the 'plus' (__add__) operation
> without overriding it in my class ?

You can't.
> I need to override *every* operator I like to use ?

Yes.

Diez



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