Re: Man pages have colors? A deep dive into groff

Junio C Hamano wrote:

Felipe Contreras [off-list ref] writes:

quoted

Why not use color.pager?

I dug a bit to refresh my memory and it turns out that the reason we
should not do so is because it means something totally different.

color.[ch] defines want_color() that applications like "diff" and
"log" can use to see if the application is configured to paint its
output in colors.

When that layer says for that particular application it should be
decided automatically, then we call into color.c::check_auto_color()
which is the only user of pager_use_color (which is set from the
color.pager configuration variable).  The purpose of that call is to
ask if the pager is capable of colors.

That is not true. check_auto_color() returns 1 when the fd is a tty.

For example advice() would indirectly call check_auto_color() and no
pager is involved.

Inside the help built-in want_color(GIT_COLOR_UNKNOWN) will always
return 1 (unless you do something like `git help git > file`).

pager_use_color is completely ignored in this case.

It's used only when 1) the fd is not a tty, 2) it's stdout, 3) git is
using a pager... Only _then_ it checks for pager_use_color
(color.pager).

So no; the first purpose of check_auto_color() is to find out if the fd
is capable of showing colors, secondary, if we are using a pager, then
check the user configuration.

In the case we are using a pager it's not check if the pager is capable
of colors, the pager could be capable of colors and yet the user would
disable them: it's the check for the user preference.

So in short, the color.pager is about "is the pager capable of
colors?"

That's not the case.

Even the documentation says so:

  color.pager::
    A boolean to enable/disable colored output when the pager is in
    use (default is true).

and the color.ui (and color.<cmd>) is about "does the user
wants output from <cmd> in color?"

Tying it directly to "color.pager" is wrong.

Why? color.pager is to enable/disable colored output when a pager is in
use.

The fact that it's man executing the pager and not git makes no
difference to the user.

Cheers.

-- 
Felipe Contreras