[Python-Dev] PEP: Adding data-type objects to Python (original) (raw)

Travis E. Oliphant oliphant.travis at ieee.org
Sun Oct 29 09:26:38 CET 2006

Martin v. Löwis wrote:

Travis E. Oliphant schrieb:

What is needed is a definitive way to describe data and then have

array struct ctypes all be compatible with that same method. That's why I'm proposing the PEP. It's a unification effort not yet-another-method. As I unification mechanism, I think it is insufficient. I doubt it can express all the concepts that ctypes supports.

Please clarify what you mean.

Are you saying that a single object can't carry all the information about binary data that ctypes allows with it's multi-object approach?

I don't agree with you, if that is the case. Sure, perhaps I've not included certain cases, so give an example.

Besides, I don't think this is the right view of "unification". I'm not saying that ctypes should get rid of it's many objects used for interfacing with C-functions.

I'm saying we should introduce a single-object mechanism for describing binary data so that the many-object approach of c-types does not become some kind of de-facto standard. C-types can "translate" this object-instance to its internals if and when it needs to.

In the mean-time, how are other packages supposed to communicate binary information about data with each other?

Remember the context that the data-format object is presented in. Two packages need to share a chunk of memory (the package authors do not know each other and only have and Python as a common reference). They both want to describe that the memory they are sharing has some underlying binary structure.

How do they do that? Please explain to me how the buffer protocol can be extended so that information about "what is in the memory" can be shared without a data-format object?

-Travis

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