Roundup Robot devn...@psf.upfronthosting.co.za added the comment:
New changeset e4617650f006 by Larry Hastings in branch 'default':
Issue #14705: Added support for the new 'p' format unit to skipitem().
http://hg.python.org/cpython/rev/e4617650f006
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Changes by Larry Hastings la...@hastings.org:
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status: open - closed
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Larry Hastings la...@hastings.org added the comment:
Attached is rev 3 of my patch, incorporating mainly backing out of dumb ideas.
Thanks for the feedback, Serhiy and Mark!
My name is Serhiy. :)
My genuine apologies! In my defense it was rather late.
'P' has the advantage that you can
Benjamin Peterson benja...@python.org added the comment:
Since no one has produced a good example needing P, I say drop it. At any
rate, it can be almost trivially imitated with O!.
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Georg Brandl ge...@python.org added the comment:
Indeed, because the code is written is not a good argument if even you
yourself are -0.
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Mark Dickinson dicki...@gmail.com added the comment:
Having meditated on it, I think either I should either just call
PyErr_Occured, check for explicit failure (val 0), or explicit success
(val = 0). I've opted for the last of those.
Yes, I think that works; it avoids a relatively
Mark Dickinson dicki...@gmail.com added the comment:
I considered briefly trying to make 'P' handle subclasses of bool.
Not an issue: bool can't be subclassed. :-)
Python 3.2.3 (default, Apr 13 2012, 00:15:25)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type help, copyright,
Serhiy Storchaka storch...@gmail.com added the comment:
That's not a reason to use 'P'. Why you should use 'P' in the first place?
I just guided by the principle Explicit is better than implicit.
Statements 'if' and 'while' I consider explicit and expect cast to bool.
Implicit cast to bool in
Larry Hastings la...@hastings.org added the comment:
Serhiy, I'm having a little trouble with your English. (But I'm sure your
English is far better than my... uh, anything besides English.) So let me ask
a question with a clear yes/no answer:
Do you still think 'P' is better than 'p'?
Serhiy Storchaka storch...@gmail.com added the comment:
Do you still think 'P' is better than 'p'?
No.
I hope I haven't made a lot of mistakes in the previous sentence.
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Larry Hastings la...@hastings.org added the comment:
I hope I haven't made a lot of mistakes in the previous sentence.
It depends, do you consider three a lot? ;-)
Attached is a new patch removing 'P'. (The regrtest is still running but I
don't expect any failures.) I'm guessing I won't
Mark Dickinson dicki...@gmail.com added the comment:
Latest patch looks good to me.
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Roundup Robot devn...@psf.upfronthosting.co.za added the comment:
New changeset bc6d28e726d8 by Larry Hastings in branch 'default':
Issue #14705: Add 'p' format character to PyArg_ParseTuple* for bool support.
http://hg.python.org/cpython/rev/bc6d28e726d8
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nosy: +python-dev
Larry Hastings la...@hastings.org added the comment:
Eh, it was ready, why wait? Thanks everybody for your feedback!
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Raymond Hettinger raymond.hettin...@gmail.com added the comment:
I would have expected a bool parse code to insist on a boolean, so that:
int x;
PyArg_ParseTupleAndKeywords(args, kwds, p:func, x);
would behave the same as:
PyObject *o;
int x;
Larry Hastings la...@hastings.org added the comment:
I would have expected a bool parse code to insist on a boolean,
I originally had a second form ('P') that insisted on a boolean as you suggest.
But nobody could come up with a use case. So I removed it in the final patch.
Please see
Roundup Robot devn...@psf.upfronthosting.co.za added the comment:
New changeset 709850f1ec67 by Larry Hastings in branch 'default':
Update Misc/NEWS for issues #14127 and #14705. (And, technically, #10148.)
http://hg.python.org/cpython/rev/709850f1ec67
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Changes by Larry Hastings la...@hastings.org:
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resolution: - fixed
stage: patch review - committed/rejected
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Roundup Robot devn...@psf.upfronthosting.co.za added the comment:
New changeset 05274ab06182 by Larry Hastings in branch 'default':
Update Misc/NEWS for issues #14127 and #14705. (And, technically, #10148.)
http://hg.python.org/cpython/rev/05274ab06182
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Eric V. Smith e...@trueblade.com added the comment:
The patch looks good to me.
Are there any places in the current code base that would use P? p seems the
more useful case.
Are you planning on changing existing code to use P or p, or just use it going
forward?
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nosy: +eric.smith
Mark Dickinson dicki...@gmail.com added the comment:
I also think that 'P' looks too strict to be really useful. I can't think of
too many cases where I'd really want to insist on a boolean argument (and
reject values of 0 or 1).
Maybe implement just 'p' for now and consider 'P' later?
Larry Hastings la...@hastings.org added the comment:
I looked through the Python sources and couldn't find any instances of a
function or method with an argument that only allowed you to pass in either
True or False.
Serily already said he would use 'P' over 'p', although I too am
Martin v. Löwis mar...@v.loewis.de added the comment:
I think there should be a test case also where PyObject_IsTrue gives an
exception (which I think can happen if __bool__ raises an exception).
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Larry Hastings la...@hastings.org added the comment:
I think there should be a test case also where PyObject_IsTrue gives an
exception (which I think can happen if __bool__ raises an exception).
I'd be happy to add such a test, but I don't know of any types like that. Can
anyone suggest
Martin v. Löwis mar...@v.loewis.de added the comment:
I think there should be a test case also where PyObject_IsTrue gives an
exception (which I think can happen if __bool__ raises an exception).
I'd be happy to add such a test, but I don't know of any types like
that. Can anyone suggest
Larry Hastings la...@hastings.org added the comment:
Added test forcing a failure for 'p' (and 'P'). This made me have to handle
errors a little differently, so it was definitely good to test it. Thanks for
the suggestion, Martin!
Also changed wording in documentation ever-so-slightly.
Eric V. Smith e...@trueblade.com added the comment:
Now that I think about this some more, I think I'd structure the 'p' tests as:
for expr in [False, None, True, 1, 0]: # add the rest
self.assertEqual(bool(expr), getargs_p(expr))
Since the salient point is that 'p' returns the same value
Serhiy Storchaka storch...@gmail.com added the comment:
Serily: why would you unhesitatingly prefer 'P' to 'p'?
My name is Serhiy. :)
'P' has the advantage that you can safely backward-compatibly remove the
restriction by replacing 'P' on 'p'. :)
I also found some funny in-between cases.
Serhiy Storchaka storch...@gmail.com added the comment:
Since the salient point is that 'p' returns the same value as bool(), right?
Yes, and bool_new() is a candidate number one for using new feature.
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Eric V. Smith e...@trueblade.com added the comment:
If bool_new() is going to use 'p', then my suggestion shouldn't be the only
test of 'p'.
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Mark Dickinson dicki...@gmail.com added the comment:
In this line in the patch (Python/getargs.c):
+if (val == -1 || PyErr_Occurred()) {
Isn't that call to PyErr_Occurred() redundant?
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Larry Hastings la...@hastings.org added the comment:
My first patch. Adds 'p' and 'P', along with documentation and unit tests.
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keywords: +patch
stage: - patch review
Added file: http://bugs.python.org/file25441/larry.parse.tuple.p.and.P.1.diff
Serhiy Storchaka storch...@gmail.com added the comment:
Patch looks good to me.
I however prefer to use 'P'.
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New submission from Larry Hastings la...@hastings.org:
Currently functions that parse their arguments with the PyArg_ParseTuple family
which want to take a boolean-ish parameter face two choices:
* take an int, then test whether or not the int is 0, or
* take an object, then call
Serhiy Storchaka storch...@gmail.com added the comment:
Yes, I too have encountered this in the process of working on issue 14626. For
this purpose it is appropriate to use a special converter (with 'O'). I
suppose it must be a strict сonverter; there is no point in specifying
followlinks=[1,
Larry Hastings la...@hastings.org added the comment:
For this purpose it is appropriate to use a special converter
(with 'O').
The converter works--but, then, a similar converter would also work
for double, and float, and long long and many others. If long long
is special enough to merit
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