[Python-3000] Revised PEP for buffer protocol (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Wed Mar 21 10:47:19 CET 2007

Josiah Carlson wrote:

Nick Coghlan <ncoghlan at gmail.com> wrote:

Josiah Carlson wrote:

"Travis E. Oliphant" <oliphant.travis at ieee.org> wrote:

The buffer interface should allow discontiguous memory areas to share standard striding information. However, consumers that do not want to deal with strided memory should also be able to request a contiguous segment easily. I don't believe this is necessary. While the point of the buffer interface is to offer direct access to memory regions of an object or structure, being able to ask "can I get a contiguous segment" isn't really reasonable. The response is either going to be "yes, that's how I represent it anyways" or "no, that's not how I represent the data". But this bit of meta information is easily acquired by getting the buffer and checking the stride. I think the point is for there to be something in the standard library or Python core that makes it easy for a consumer to copy the data to a contiguous memory segment in the event the consumer can't directly handle non-contiguous data (e.g. a C API function that takes the source object, a pointer to the destination memory block, and an optional slice object defining a subsection of the memory block to be retrieved) But that still isn't a use-case for the "I want a contiguous view". The consumer needs to construct a memory region, copy the non-contiguous data, then pass it on somewhere else. The object offering the original view shouldn't need to offer anything special to make it happen.

It's a use case that any C API updates associated with this PEP need to handle though. It's along the lines of a type supporting 3 different abstract C API functions just by providing a tp_index slot.

Cheers, Nick.

-- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia

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