[Patches] [ python-Patches-1610575 ] C99 _Bool support for struct

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Thu Dec 7 06:37:43 CET 2006


Patches item #1610575, was opened at 2006-12-07 05:37
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Category: Modules
Group: Python 2.6
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: David Remahl (chmod007)
Assigned to: Nobody/Anonymous (nobody)
Summary: C99 _Bool support for struct

Initial Comment:
C99 adds the fundamental _Bool integer type (fundamental in the sense that it is not equivalent to or a composite of any other C type). Its size can vary from platform to platform; the only restriction imposed by the C standard is that it must be able to hold the values 0 or 1. Typically, sizeof _Bool is 1 or 4.

A struct module user trying to parse a native C structure that contains a _Bool member faces a problem: struct does not have a format character for _Bool. One is forced to hardcode a size for bool (use a char or an int instead).

This patch adds support for a new format character, 't', representing the fundamental type _Bool. It is handled sementically as representing pure booleans -- when packing a structure the truth value of the argument to be packed is used and when unpacking either True or False is always returned.

For platforms that don't support _Bool, as well as in non-native mode, 't' packs as a single byte.

Test cases are included, as well as a small change to the struct documentation. The patch modifies configure.in to check for _Bool support, and the patch includes the autogenerated configure and pyconfig.h.in files as well.

I have tested the module on Mac OS X x86 (uses 1 byte for _Bool) and Mac OS X ppc (uses 4 bytes for _Bool). Ran regression suite.

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