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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: CP65001 fails (was re: ...)
Date: Sun, 15 Dec 2013 00:07:09 -0500
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On 12/14/2013 9:39 PM, Steven D'Aprano wrote:
> On Sat, 14 Dec 2013 13:43:41 -0500, Terry Reedy wrote:
>
>> This was reported by Victor Stinner as part of
>> http://bugs.python.org/issue19914
>> to explain how cp65001 causes behavior like this with Python's
>> interactive help() function (which more for paging on Windows).
>>
>>   >>> help(str)
>> Not enough memory.
>
>
> Terry, I see you have closed the bug report. I think you were a little
> hasty.

I might have been premature, but I was not hasty. I read the SO reports 
and though about it for an hour or so while looking at other issues. I 
did not see any use to leaving it open as I did not see any realistic 
propect of a useful and acceptible patch to Python. The OP himself said 
that i/o did not work with 65001 and that not using it fixed his issue.

> The ultimate cause of the bug may be the failure of Window's
> "more" command when the code-page is set to CP-65001, but that doesn't
> necessarily imply that Python shouldn't, or can't, do something about it.

I believe running Python on Windows with cp=65001 falls in the category 
of "Don't do that". This is based on my experiences and the reported 
experience of other developers who have tried and failed to make it 
work, reinforced by the SO thread and a couple of other web pages.

> The interactive help system already supports different pagers, depending
> on the environment. I think that it could fall back on a more primitive
> pager if the preferred one fails.

Do you know if 'more' actually signals failure?
Do you know if there are any other situations in which a pager fails?

> The relevant code is the pager() and
> getpager() functions in the pydoc module. The patch won't be trivial, but
> I think it can be done, and I think it should be done. Although possibly
> for Python 3.5 rather than a bug-fix version. Your thoughts?

My thought is that if the only situation in which a pager fails is one 
that one should not use, because other things will also fail, then a 
patch would not be worth the bother.

-- 
Terry Jan Reedy