[Python-Dev] Assertion in _PyManagedBuffer_FromObject() (original) (raw)

Nick Coghlan ncoghlan at gmail.com
Sat Mar 3 00:49:34 CET 2012

On Sat, Mar 3, 2012 at 3:14 AM, Stefan Behnel <stefan_ml at behnel.de> wrote:

Stefan Krah, 02.03.2012 17:42:

The reason why this scheme was not chosen for a chain of memoryviews was that 'exporter' (in theory) could implement a slideshow of buffers, which means that in the face of redirecting requests m might not be equal to nd. Right. Then it's only safe when the intermediate provider knows what the underlying buffer providers do. Not unlikely in an application setting, though, and it could just be an option at creation time to activate the delegation for the ndarray above.

OK, my take on the discussion so far:

  1. assert() is the wrong tool for this job (it should trigger a Python error message)
  2. the current check is too strict (it should just check for obj != NULL, not obj == &exporter)
  3. the current check is in the wrong place (it should be in PyObject_GetBuffer)

Sound about right?

Cheers, Nick.

-- Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia

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