[Python-3000] Possible Duck Typing Problem in Python 2.5?

[Daniel Stutzbach]

On Dec 9, 2007 3:21 PM, hashcollision <hashcollision at gmail.com> wrote:

> From http://ivory.idyll.org/blog/dec-07/conversions.html:
>
> class X:
>     internal = [5,6,7,8]
>     def __getitem__(self, i):
>         return self.internal[i]
>
> x = X()
>
> l = [1,2,3]
> print l + x
>
> fails with
>
> TypeError: can only concatenate list (not "instance") to list
>
> If you want class X to understand "+" via duck-typing, overload __add__
and __radd__.

-- 
Daniel Stutzbach, Ph.D.             President, Stutzbach Enterprises LLC
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