Re: [PATCH 2/3] pager: factor out a helper to prepare a child process to run the pager

[Jeff King <peff@peff.net>]

On Tue, Feb 16, 2016 at 03:49:55PM -0800, Junio C Hamano wrote:

> > And if you put the git_pager() call inside prepare_pager_args (which I
> > agree would be cleaner), we just have:
> >
> >   void prepare_pager_args(struct child_process *pager_process);
> >
> > which is pretty self-explanatory (though it might need a new name; I'd
> > be tempted to call it init_pager_process() or something, and actually
> > have it do the child_process_init() to make sure it is working with a
> > sane clean slate).
> 
> Conceptually I am on the same page, but I am not sure how well that
> interacts with what "git am -i" codepath wants to do, though.
> 
> One big difference between the "we'll feed our output to pager"
> codepath and "we'll spawn a pager to let a file on the filesystem be
> read" codepath is that the former needs to call git_pager() and
> check the NULL-ness of the return value to decide that it does not
> want to spawn a pager and let the standard output just go straight
> to the outside world.  The latter, on the other hand, does want to
> spawn something to cause the file to be presented to the end user
> even git_pager() returns NULL.
> 
> And that is why I didn't make this helper call git_pager() itself.

That makes sense. I didn't dig into it carefully. I saw the "pager=cat"
thing in the context of your diff to git-am, and assumed it was weird
fallback that should be done by the regular pager infrastructure. But
it's the exact thing you're talking about here.

So of all of the things I suggested, I think the non-varargs one that
takes "pager" as a string makes the most sense.

-Peff