[Python-Dev] Allocation of shape and strides fields in Py_buffer

[Greg Ewing]

Antoine Pitrou wrote:

> - it uses something (Py_buffer) which is not a PyObject and has totally
> different allocation/lifetime semantics

This was a deliberate decision -- in fact I argued for it myself.
The buffer interface is meant to be a minimal-overhead way for
C code to get at the underlying data. Requiring allocation of
a PyObject would be too expensive.

The way to think about the Py_buffer struct is not as an
object in its own right, but just a place to put some output
parameters from the GetBuffer call.

The lifetime of the information pointed to by the Py_buffer
is the same as the lifetime of the underlying object, and that
object is responsible for managing it.

> - it doesn't specify how to obtain e.g. a sub-buffer, or even duplicate an
> existing one (which seem to be rather fundamental actions to me)

I don't think they're as fundamental as all that. But some
utilities for doing things like this could be useful, as I
mentioned in another post.

-- 
Greg