[Python-Dev] Possible bug in complexobject.c (still in Python 2.5)

Travis E. Oliphant oliphant.travis at ieee.org
Thu Jun 1 02:27:50 CEST 2006

I'm curious about the difference between

float_subtype_new  in floatobject.c
complex_subtype_from_c_complex in complexobject.c

The former uses type->tp_alloc(type, 0) to create memory for the object 
while the latter uses PyType_GenericAlloc(type, 0) to create memory for 
the sub-type (thereby by-passing the sub-type's own memory allocator).

It seems like this is a bug.   Shouldn't type->tp_alloc(type, 0) also be 
used in the case of allocating complex subtypes?

This is causing problems in NumPy because we have a complex type that is 
a sub-type of the Python complex scalar.  It sometimes uses the 
complex_new code to generate instances (so that the __new__ interface is 
the same),  but because complex_subtype_from_c_complex is using 
PyType_GenericAlloc this is causing errors.

I can work around this by not calling the __new__ method for the base 
type but this is not consistent.

Thanks for any feedback,


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