On Wed, Apr 19, 2017 at 10:44 AM Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Kaushal Modi <kaushal.modi@gmail.com>
> > Date: Wed, 19 Apr 2017 12:38:52 +0000
> > Cc: Clément Pit-Claudel <cpitclaudel@gmail.com>,
> >       Emacs developers <emacs-devel@gnu.org>, yuri.v.khan@gmail.com
> >
> > I learnt recently that foo-p naming convention is only for predicate
> > functions that return nil or non-nil.
>
> We have several dozen of variables in Emacs whose names end in "-p".
>

It's just a convention, and it makes sense so I suggested that.

I ran ag in emacs/lisp:

1. 1511 matches -- defuns and defsubsts ending in -p -- ag
'def(un|subst)\s+[^ ]+-p\s+' --stats
2. 149 matches -- defvars, defconsts and defcustoms ending in -p -- ag
'def(var|const|custom)\s+[^ ]+-p\s+' --stats
3. 65 matches -- Just the user-facing defcustoms -- ag 'defcustom\s+[^
]+-p\s+' --stats

So it is correct that there are dozens of variables that end in -p, but
it's a stronger convention to have -p in functions.
-- 

Kaushal Modi