[Python-Dev] PEP: Adding data-type objects to Python

[Travis Oliphant]

Martin v. Löwis wrote:
> Travis E. Oliphant schrieb:
> 
>>>2. Should primitive type codes be characters or integers (from an enum) at
>>>C level?
>>>    - I prefer integers
>>
>>>3. Should size be expressed in bits or bytes?
>>>    - I prefer bits
>>>
>>
>>So, you want an integer enum for the "kind" and an integer for the 
>>bitsize?   That's fine with me.
>>
>>One thing I just remembered.  We have T_UBYTE and T_BYTE, etc. defined 
>>in structmember.h already.  Should we just re-use those #defines while 
>>adding to them to make an easy to use interface for primitive types?
> 
> 
> Notice that those type codes imply sizes, namely the platform sizes
> (where "platform" always means "what the C compiler does"). So if
> you want to have platform-independent codes as well, you shouldn't
> use the T_ codes.
> 

In NumPy we've found it convenient to use both.   Basically, we've set 
up a header file that "does the translation" using #defines and typedefs 
to create things like (on a 32-bit platform)

typedef npy_int32  int
#define NPY_INT32 NPY_INT

So, that either the T_code-like enum or the bit-width can be used 
interchangable.

Typically people want to specify bit-widths (and see their data-types in 
bit-widths) but in C-code that implements something you need to use one 
of the platform integers.

I don't know if we really need to bring all of that over.

-Travis