On 05/07/2012 07:00 PM, Stefan Behnel wrote:
mark florisson, 07.05.2012 18:28:
On 7 May 2012 17:00, Dag Sverre Seljebotn wrote:
On 05/07/2012 04:16 PM, Stefan Behnel wrote:
Stefan Behnel, 07.05.2012 15:04:
Dag Sverre Seljebotn, 07.05.2012 13:48:
BTW, with the coming of memoryviews, me and Mark talked about just
deprecating the "mytype[...]" meaning buffers, and rather treat it as
np.ndarray, array.array etc. being some sort of "template types". That
is,
we disallow "object[int]" and require some special declarations in the
relevant pxd files.
Hmm, yes, it's unfortunate that we have two different types of syntax
now,
one that declares the item type before the brackets and one that declares
it afterwards.
I actually think this merits some more discussion. Should we consider the
buffer interface syntax deprecated and focus on the memory view syntax?
I think that's the very-long-term intention. Then again, it may be too early
to really tell yet, we just need to see how the memory views play out in
real life and whether they'll be able to replace np.ndarray[double] among
real users. We don't want to shove things down users throats.
But the use of the trailing-[] syntax needs some cleaning up. Me and Mark
agreed we'd put this proposal forward when we got around to it:
- Deprecate the "object[double]" form, where [dtype] can be stuck on any
extension type
- But, do NOT (for the next year at least) deprecate np.ndarray[double],
array.array[double], etc. Basically, there should be a magic flag in
extension type declarations saying "I can be a buffer".
For one thing, that is sort of needed to open up things for templated cdef
classes/fused types cdef classes, if that is ever implemented.
Deprecating is definitely a good start.
Then the first step on that road is to rework the documentation so that it
pushes users into going for memory views instead of the plain buffer syntax.
-1, premature.
Dag
I think at least if you only
allow two types as buffers it will be at least reasonably clear when
one is dealing with fused types or buffers.
Basically, I think memoryviews should live up to demands of the users,
which would mean there would be no reason to keep the buffer syntax.
One thing to do is make memoryviews coerce cheaply back to the
original objects if wanted (which is likely). Writting
np.asarray(mymemview) is kind of annoying.
... and also doesn't do the same thing, I believe.
Also, OT (sorry), but I'm kind of worried about the memoryview ABI. If
it changes (and I intend to do so), cython modules compiled with
different cython versions will become incompatible if they call each
other through pxds. Maybe that should be defined as UB...
Would there be a way to only use the plain buffer interface for cross
module memory view exchange? That could be an acceptable overhead to pay
for ABI independence.
Stefan
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