What is the best way of allocating array of bytes in Cython and passing it back to Python?

Question

I have a Cython function like cdef generate_data(size) where I'd like to:

initialise an array of bytes of length size
call external (C) function to populate the array using array ptr and size
return the array as something understandable by Python (bytearray, bytes, your suggestions)

I have seen many approaches on the internet but I'm looking for the best/recommended way of doing this in my simple case. I want to:

avoid memory reallocations
avoid using numpy
ideally use something that works in Python 3 and 2.7, although a 2.7 solution is good enough.

I'm using Cython 0.20.

I believe you have to be more specific in order to get good answers... — Saullo G. P. Castro, May 25 '14 at 18:16
I wanted to be as generic as possible since I wanted to know the typical (canonical?) way of solving this class of problems. — zxxc, May 28 '14 at 17:51

score 1 · Accepted Answer · edited May 23 '17 at 12:27

1

For allocating memory, I have you covered.

After that, just take a pointer (possibly at the data attribute if you use cpython.array.array like I recommend) and pass that along. You can return the cpython.array.array type and it will become a Python array.

edited May 23 '17 at 12:27

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answered May 25 '14 at 18:56

Veedrac

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What is the best way of allocating array of bytes in Cython and passing it back to Python?

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