[Numpy-discussion] Can't add user defined complex types

[Neal Becker]

Travis E. Oliphant wrote:

> Neal Becker wrote:
>> In arrayobject.c, various complex functions (e.g., array_imag_get) use:
>> PyArray_ISCOMPLEX -> PyTypeNum_ISCOMPLEX,
>> which is hard coded to 2 predefined types :(
>>
>> If PyArray_ISCOMPLEX allowed user-defined types, I'm guessing functions
>> such as array_imag_get would just work?
>>   
> I don't think that it true.   There would need to be some kind of idea
> of "complex-ness" that is tested.   One way this could work is if your
> corresponding scalar inherited from the generic complex scalar type and
> then that was tested for.
> 
> -Travis O.

You don't think which is true?

Suppose along with registering a type, I can mark whether it is complex. 
Then we change PyArray_ISCOMPLEX to look at that mark for user-defined
types.

I believe get_part will just work.  I more-or-less copied the code, and made
my own functions 'get_real, get_imag', and they work just fine on my types.