bug#46627: [PATCH] Add new help command 'describe-command'

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Sun, 21 Feb 2021 01:18:02 -0600
> Cc: eliz@gnu.org, larsi@gnus.org, 46627@debbugs.gnu.org
> 
> I can't claim that it is the most effective technique in general.
> I would use it when I am certain that I almost know the name of a
> command -- I would know it if I see it.  In such situations, firing up
> apropos is an extra step and not what I want.

Can you explain how apropos is an extra step, compared to TAB
completion followed by browsing through the candidates?  I see no
extra step here.

> But I think the use of `describe-command' goes beyond this one use-case.
> In particular, I don't think end-users should need to filter through a
> massive, intimidating list of functions when they are just looking for a
> command.

"C-h a" accomplishes that.  It is no accident that it's the very first
Help command mentioned in the user manual.  In addition, "C-h a" is
more powerful, as it accepts regular expressions and lists of
keywords, whereas completion has only crude and less powerful
approximations of those.

> (BTW, in the completion framework I often use, `ivy', there is a command
> to run the action associated with the minibuffer without leaving the
> minibuffer.  That is, I run `C-h f', type in some text to complete on,
> and then hit `C-M-n' to repeatedly see the full documentation for a
> number of commands.

You can likewise type "C-h a", then, with point on the command you
were after, type "M-x <DOWN> RET" or "M-x M-n RET" to invoke that
command.  So the task of finding a command and then quickly invoking
it already has a well-developed solution in Emacs, one that is more
powerful than completion.