[issue27274] [ctypes] Allow from_pointer creation

[Memeplex]

Memeplex added the comment:

As usual, thank you for the detailed and informative answer, Eryk. I think I understand your points but I decided to do it the way I did it because:

1. I sometimes need the array itself. For example, some of my clases contains or inherits from a ctypes structure with pointers (to an array of memory). Usually I name these pointers with a leading underscore and expose them as properties returning ctypes arrays.

2. For pickling/unpickling ctypes arrays provide a convenient middle-point between bytes objects and ctypes pointers. Getting a bytes object from an array is as easy as calling bytes() on it. OTOH, the array can be directly assigned to a compatible pointer structure field.

3. While the overloaded c_array(ptr, size)/c_array(type, bytes) is not the most efficient api to get bytes from a pointer and viceversa, it's very simple for the range of uses cases (1 and 2) it covers. Nevertheless, I have benchmarked the perfomance and it's not that terrible.

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<http://bugs.python.org/issue27274>
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