[Cython] Buffer syntax/array primitive type

[Dag Sverre Seljebotn]

Prabhu Ramachandran wrote:
> On 03/08/09 04:07, Dag Sverre Seljebotn wrote:
>> Anyway, I feel myself that this has a better feel than a new array type,
>> as it makes use of the buffer interface and so bridges better with
>> Python-land.
>>
>> My proposal is here:
>> http://wiki.cython.org/enhancements/buffersyntax
>
> This looks really nice.  I'm just a little curious about one little
> feature, would this support resizing the buffer?  i.e. could I do
>
>   def f(int[:] arr):
>       cdef int i
>       # ...
>       arr.append(i)

No, this would never happen. This is defined as syntax candy for PEP 3118,
which exports a view to allocated memory but doesn't say anything about
how that memory is allocated or deallocated.

I believe we must solve this, but in a different way. Given that we get a
"fast list", wouldn't we then want a "fast dict"?

Adding a type templating mechanism to Cython is not out of the question I
think, there was some talk 3/4 year ago. But now I myself believe the most
promising option is to wrap C++ in a very good way, so that one can do
something along the lines of

cdef cpp.vector[int] arr = cpp.vector[int]()
cdef cpp.map[str, cpp.vector[int]] map = cpp.map[str, cpp.vector[int]]()
arr.push_back(3)
map[40] = arr

(Yes, those lines raises about 10 questions about reference counting vs.
copy-by-value semantics; making C++ access feel Pythonic is part of such a
challenge IMO.)

Dag Sverre