[ python-Bugs-1563759 ] struct.unpack doens't support buffer protocol objects

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Bugs item #1563759, was opened at 2006-09-22 17:17
Message generated for change (Comment added) made by rhettinger
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Category: Python Library
Group: Python 2.5
Status: Open
Resolution: None
>Priority: 7
Private: No
Submitted By: Adal Chiriliuc (adalx)
Assigned to: Nobody/Anonymous (nobody)
Summary: struct.unpack doens't support buffer protocol objects

Initial Comment:
If you pass an object which supports the buffer
protocol to struct.unpack it will fail because it
specifically checks for a string.

You should use PyObject_AsReadBuffer instead.

If this code is performance critical, you could add an
unpack_buffer method or something like that.

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>Comment By: Raymond Hettinger (rhettinger)
Date: 2007-04-03 19:45

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This was due to Bob Ippolito's commit in revision 46184.

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Comment By: Adal Chiriliuc (adalx)
Date: 2006-09-23 07:57

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test_struct_run.py works in 2.4, throws exception in 2.5

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Comment By: Adal Chiriliuc (adalx)
Date: 2006-09-23 07:56

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The actual code which broke used a Pointer extension class
implemented in C++.

I reproduced the problem using array.array. Using array in
this way (without calling tostring) looks a bit weird.


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Comment By: Martin v. Löwis (loewis)
Date: 2006-09-23 07:12

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Ah, so you say that was working previously? It's a bug,
then. Can you provide a test case?

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Comment By: Adal Chiriliuc (adalx)
Date: 2006-09-23 06:37

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Well, because it broke previously working code and there is
no warning in the documentation about that.

In the mean-time, I've found out about pack_into and
unpack_from which accept buffer like objects. Note that they
are not documented in the struct module section, only
mentioned in the "What's new" chapter.

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Comment By: Martin v. Löwis (loewis)
Date: 2006-09-23 06:19

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Why is this a bug?

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