bug#57481: elisp code utilising derived-mode-parent

[Christopher Dimech <dimech@gmx.com>]

> Sent: Wednesday, August 31, 2022 at 10:07 AM
> From: "Phil Sainty" <psainty@orcon.net.nz>
> To: "Christopher Dimech" <dimech@gmx.com>
> Cc: "Eli Zaretskii" <eliz@gnu.org>, 57481@debbugs.gnu.org
> Subject: Re: bug#57481: elisp code utilising derived-mode-parent
>
> On 2022-08-31 01:16, Christopher Dimech wrote:
> > It could find things through and do what it has to do,
> > without requirements for user mode loading.
>
> Except that what it needs to do is load the mode.
>
> If you're now saying that you're actually happy for the mode
> to be loaded just so long as the user doesn't have to do it
> themselves, then you can do that for autoloaded modes.
> Check autoloadp and, if non-nil, call autoload-do-load.

It has been a misinterpretation.  Not-loading was a reference to
make the loading requirement fall upon the user.  Unless the
user has already loaded it or was loaded it for whatever task
user is doing, then I can load the mode appropriately when the
user calls the function.

> For modes which are neither loaded nor known as autoloads,
> Emacs doesn't even know they exist, let alone how to tell
> you what they derive from.

Can scrutinise that some other time.