Re: [PATCH] Implement XDG Base Directory specification for user-emacs-directory

[Eli Zaretskii <eliz@gnu.org>]

Ping!  This seems to have stalled.  Can we please revive it and make
the changes in the repository?

TIA

> Date: Sun, 28 Jul 2019 17:48:34 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> CC: emacs-devel@gnu.org
> 
> > From: Paul Eggert <eggert@cs.ucla.edu>
> > Date: Sat, 27 Jul 2019 11:46:31 -0700
> > 
> > I'll give it a whirl. Proposed patch attached.
> 
> Thanks.
> 
> > They can set XDG_CONFIG_DIR to /nowhere to go back to the old way,
> > as an emergency fix to get Emacs up and running well enough to fix
> > their configuration.
> 
> I think we should mention this part in NEWS.
> 
> > --- a/doc/emacs/custom.texi
> > +++ b/doc/emacs/custom.texi
> > @@ -2219,28 +2219,33 @@ Init File
> >  @cindex init file
> >  @cindex .emacs file
> >  @cindex ~/.emacs file
> > -@cindex ~/.config/emacs file
> > +@cindex ~/.config/emacs/init.el file
> >  @cindex Emacs initialization file
> >  @cindex startup (init file)
> > +@cindex XDG_CONFIG_HOME
> >  
> >    When Emacs is started, it normally tries to load a Lisp program from
> >  an @dfn{initialization file}, or @dfn{init file} for short.  This
> > -file, if it exists, specifies how to initialize Emacs for you.  Emacs
> > -looks for your init file using the filenames
> > -@file{~/.config/emacs},. @file{~/.emacs}, @file{~/.config/emacs.el},
> > -@file{~/.emacs.el}, @file{~/.config/emacs.d/init.el} or
> > -@file{~/.emacs.d/init.el}; you can choose to use any one of these
> > -names (@pxref{Find Init}).  Here, @file{~/} stands for your home
> > +file, if it exists, specifies how to initialize Emacs for you.
> > +If the directory @file{@var{xdghome}/.config/emacs} exists, Emacs uses
> > +@file{@var{xdghome}/.config/emacs/init.el} as the init file.  Here,
> > +@var{xdghome} stands for the value of the environment variable
> > +@env{XDG_CONFIG_HOME}, or for @file{~/.config} if
> > +@env{XDG_CONFIG_HOME} is unset; @file{~/} stands for your home
> >  directory.
> >  
> > -  While the @file{~/.emacs} and @file{~/.emacs.d/init.el} locations
> > -are backward-compatible to older Emacs versions, and the rest of this
> > -chapter will use them to name your initialization file, it is better practice
> > -to group all of your dotfiles under @file{.config} so that if you have
> > +  If @file{~/.config/emacs} does not exist, Emacs looks for your init
> > +file using the filenames @file{~/.emacs}, @file{~/.emacs.el}, or
> > +@file{~/.emacs.d/init.el}; you can choose to use any one of these
> > +names (@pxref{Find Init}).  Although this is backward-compatible
> > +with older Emacs versions, modern POSIX platforms prefer putting your
> > +initialization files under @file{.config} so that if you have
> >  to troubleshoot a problem that might be due to a bad init file, or
> >  archive a collection of them, it can be done by renaming or
> >  copying that directory.  Note that the @file{.config} versions
> >  don't have a leading dot on the basename part of the file.
> > +For convenience the rest of this section assumes @env{XDG_CONFIG_HOME}
> > +is unset or has a value equivalent to @file{~/.config}.
> 
> I think the test which describes in detail how Emacs finds the init
> file should be in the section by that name; otherwise it makes no
> sense to have that section in the first place.  The "Init File"
> section should just mention the possible places and refer to that
> other section for the details.
> 
> > diff --git a/etc/NEWS b/etc/NEWS
> > index d876c95e68..7703fc1e79 100644
> > --- a/etc/NEWS
> > +++ b/etc/NEWS
> > @@ -135,6 +135,14 @@ builds respectively.
> >  \f
> >  * Startup Changes in Emacs 27.1
> >  
> > ++++
> > +** Emacs now uses the XDG convention for init files.
> > +For example, it looks for init.el in ~/.config/emacs/init.el.
> > +Emacs continues to look for init files in their traditional locations
> > +if ~/.config/emacs does not exist.  The XDG_CONFIG_HOME environment
> > +variable (default ~/.config) specifies the parent directory of these
> > +configuration files.
> 
> As mentioned above, I think we should tell here how to get back the
> old behavior.
> 
> > diff --git a/lisp/subr.el b/lisp/subr.el
> > index eea4e045dd..8b50748a59 100644
> > --- a/lisp/subr.el
> > +++ b/lisp/subr.el
> > @@ -2930,10 +2930,15 @@ temp-buffer-setup-hook
> >  mode.")
> >  
> >  (defconst user-emacs-directory
> > -  (if (eq system-type 'ms-dos)
> > -      ;; MS-DOS cannot have initial dot.
> > -      "~/_emacs.d/"
> > -    "~/.emacs.d/")
> > +  (let ((config-dir (concat (or (getenv-internal "XDG_CONFIG_HOME")
> > +				"~/.config")
> > +			    "/emacs/")))
> > +    (if (file-exists-p config-dir)
> > +	config-dir
> 
> Can this be a defconst?  It probes the existence of an environment
> variable and a directory, so it must be done at run time, not at build
> time, I think.