[Python-Dev] PEP: Adding data-type objects to Python
Travis E. Oliphant
oliphant.travis at ieee.org
Thu Nov 2 06:01:50 CET 2006
Alexander Belopolsky wrote:
> Travis Oliphant <oliphant.travis <at> ieee.org> writes:
>> Don't lump those ideas together. Shapes and strides are necessary for
>> N-dimensional array's (it's essentially what *defines* the N-dimensional
>> array). I really don't want to sacrifice those in the extended buffer
>> protocol. If you want to separate them into different functions then
>> that is a possibility.
> I don't understand. Do you want to discuss shapes and strides separately
> from the datatype or not? Note that in ctypes shape is a property of
> datatype (as in c_int*2*3). In your proposal, shapes and strides are
> communicated separately. This presents a unique memory management
> challenge: if the object does not contain shape information in a ready to
> be pointed to form, who is responsible for deallocating the shape array?
Perhaps a "view object" should be returned like /F suggests and it
manages the shape, strides, and data-format.
>>> If we manage to agree on the standard way to pass primitive type information,
>>> it will be a big achievement and immediately useful because simple arrays are
>>> already in the standard library.
>> We could start there, I suppose. Especially if it helps us all get on
>> the same page.
> Let's start:
> 1. Should primitive types be associated with simple type codes (short, int, long,
> float, double) or type/size pairs [(int,16), (int, 32), (int, 64), (float, 32),
> (float, 64)]?
> - I prefer pairs
> 2. Should primitive type codes be characters or integers (from an enum) at
> C level?
> - I prefer integers
Are these orthogonal?
> 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?
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