Re: [PATCH v7 02/10] Stop starting pager recursively

From: Junio C Hamano <gitster@pobox.com>
Date: Feb 28, 2012, 19:10 UTC
Message-ID: <7vipiqzsd8.fsf@alter.siamese.dyndns.org>
In-Reply-To: <7v4nua25cz.fsf@alter.siamese.dyndns.org>

Junio C Hamano <gitster@pobox.com> writes:

Show 16 quoted lines

> Nguyễn Thái Ngọc Duy <pclouds@gmail.com> writes:
>
>> git-column can be used as a pager for other git commands, something
>> like this:
>>
>>     GIT_PAGER="git -p column --mode='dense color'" git -p branch
>>
>> The problem with this is that "git -p column" also has $GIT_PAGER
>> set so the pager runs itself again as a pager, then again and again.
>>
>> Stop this.
>
> A natural question that may come after reading only the above is if "git
> column" is the only one that has this problem.  In other words, is the
> undesirable behaviour you observed caused by a bug in setup_pager() that
> needs to be fixed, or should it be fixed in "git column"?

Put another way, if there is another git command X that can be used as a filter to the output of a git command Y, do you suffer from the same issue to when you abuse the GIT_PAGER mechanism to pipe the output from Y to X? That is a sure sign that the pager mechanism needs improvement (obviously, an alternative answer could be "don't do that then", though).

For example, shortlog is designed to be X for Y=log, i.e.

	$ git log v1.0.0.. | git shortlog

is a perfectly valid way to use the command. I could imagine that this patch may improve the situation if you abuse GIT_PAGER mechanism to implement the above pipeline, i.e.

	$ GIT_PAGER="git -p shortlog" git log v1.0.0..

Although I never tried it.