[ python-Feature Requests-1075902 ] ignore element format character for PyArg_ParseTuple

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Feature Requests item #1075902, was opened at 2004-11-30 05:28
Message generated for change (Comment added) made by rhettinger
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Category: None
Group: None
>Status: Closed
>Resolution: Rejected
Priority: 5
Submitted By: Sean Proctor (sproctor)
Assigned to: Nobody/Anonymous (nobody)
Summary: ignore element format character for PyArg_ParseTuple

Initial Comment:
Some kind of option to indicate there is an element,
but we don't care about its value would be nice. It
could be _. then an example would be:
PyArg_ParseTuple (tuple, "_i", &my_int);

This indicates that there is another value before the
int, but we don't care about it one way or the other.

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>Comment By: Raymond Hettinger (rhettinger)
Date: 2004-12-14 21:49

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Am closing this RFE.  It has a -1 from three developers.  The 
benefits, if any, are minor and do not warrant the time to 
implement, test, document, etc.

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Comment By: Martin v. Löwis (loewis)
Date: 2004-12-09 18:21

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So just call the variable _:

PyObject *_;

PyArg_ParseTuple(tuple, "Oi", &_, &my_int);

Given that this is possible today already, I expect that
this RFE will be considered so minor that it won't be
implemented anytime soon. It increases the learning curve
for a nearly-unnoticable convenience.

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Comment By: Sean Proctor (sproctor)
Date: 2004-12-09 00:37

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that would turn my example into PyArg_ParseTuple (tuple,
"Oi", _, &my_int);

I don't particularly care. I thought it was a good
suggestion. To me _ looks like a blank. I wouldn't really
want to use it in a format string for something besides an
any/none scenario. Your reasoning about preserving format
characters seems really weak.

You've never had a tuple where you didn't care about the
value of each element?

Somewhat separate topic. Could you say "PyArg_ParseTuple
(tuple, "Oi", NULL, &my_int);" ? I guess that would be a
less elegant way of doing what I intended.

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Comment By: Tim Peters (tim_one)
Date: 2004-12-09 00:04

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If you want to make C code look like ML, declare

PyObject** _;

and use _ in the argument list.

I'm -1 on this:  the case has almost never arisen in my 
experience, and the limited pool of format characters should 
be preserved for high-value uses.

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Comment By: Sean Proctor (sproctor)
Date: 2004-12-08 22:35

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If I use O, then I need to have a variable to store it in. I
think it's less readable. Like with pattern matching in ML,
you can use a variable instead of _, but it's not obvious
that you aren't going to use that value. With some kind of
place holder, this is made clear, and I don't need to create
a variable to store a value that I don't care about.

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Comment By: Martin v. Löwis (loewis)
Date: 2004-12-08 16:42

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What's wrong with using O as the format character?

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