[Python-Dev] Semantics of __int__(), __index__()

Ethan Furman ethan at stoneleaf.us
Thu Apr 4 17:16:26 CEST 2013

On 04/04/2013 08:01 AM, Chris Angelico wrote:
> On Fri, Apr 5, 2013 at 1:59 AM, Guido van Rossum <guido at python.org> wrote:
>> On Thu, Apr 4, 2013 at 7:47 AM, Chris Angelico <rosuav at gmail.com> wrote:
>>> Is there any argument that I can pass to Foo() to get back a Bar()?
>>> Would anyone expect there to be one? Sure, I could override __new__ to
>>> do stupid things, but in terms of logical expectations, I'd expect
>>> that Foo(x) will return a Foo object, not a Bar object. Why should int
>>> be any different? What have I missed here?
>> A class can define a __new__ method that returns a different object. E.g.
>> (python 3):
> Right, I'm aware it's possible. But who would expect it of a class?

FTR I'm in the int() should return an int camp, but to answer your question: my dbf module has a Table class, but it 
returns either a Db3Table, FpTable, VfpTable, or ClpTable depending on arguments (if creating a new one) or the type of 
the table in the existing dbf file.


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