Re: where does Alt become Meta?

[Johan Bockgård]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Will Parsons <oudeis@nodomain.invalid>
[...]
> I think you might be confusing two different issues: Emacs does
> recognize an Alt prefix, and it is different from the Meta prefix.
> A-q is always unbound in Emacs by default.

Emacs only recognizes Alt if there is a separate Meta.

>> Where does Emacs map Alt combinations to Meta combinations?
>
> Nowhere.  This is done outside Emacs's keymaps.

Unless there are Meta keys, Emacs reinterprets Alt as Meta.

  [xterm.c]

  /* If we couldn't find any meta keys, accept any alt keys as meta keys.  */
  if (! dpyinfo->meta_mod_mask)
    {
      dpyinfo->meta_mod_mask = dpyinfo->alt_mod_mask;
      dpyinfo->alt_mod_mask = 0;
    }

  /* If some keys are both alt and meta,
     make them just meta, not alt.  */
  if (dpyinfo->alt_mod_mask & dpyinfo->meta_mod_mask)
    {
      dpyinfo->alt_mod_mask &= ~dpyinfo->meta_mod_mask;
    }


cf. http://www.emacswiki.org/cgi-bin/wiki/MetaKeyProblems

-- 
Johan Bockgård