bug#56258: Changing major-mode with mouse event

[Lars Ingebrigtsen <larsi@gnus.org>]

Phil Sainty <psainty@orcon.net.nz> writes:

> Major modes would need to be identifiable as such in order to
> provide the menu you propose, and I don't believe there's a reliable
> way to do that at present for all major modes.
>
> We can identify major modes defined with `define-derived-mode'
> however, as all such modes have a `derived-mode-parent' property;
> and that does cover the majority.

Yes, it should be possible to provide a command to allow you to choose
between modes.  But I think having something like that callable from the
mode line would be of limited value, but perhaps not?  The reason is
that we just have So Many Modes -- over 500, at least, so discovering
modes via a menu would be cumbersome.

> p.s. Tangentially, I think it would be good if all symbols for both
> major and minor modes had (or rather, were expected to have) symbol
> properties to explicitly identify which type of mode they are,
> including differentiation between the various minor mode types
> (buffer-local, global, and 'globalized' pairings), as I think there
> would be other uses for being able to query the available modes.

Yes, that might be nice if you want to explore "what are the major
modes I can possibly use here?".

We almost kinda sorta have that.  All minor modes should be defined via
define-minor-mode now, and that updates the global-minor-modes and
local-minor-mode variables.  So all mode functions that aren't there are
major modes, so we could use heuristics to get us pretty far (along with
`derived-mode-parent').

However, we do have functions that end with -mode that aren't modes.

-- 
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   bloggy blog: http://lars.ingebrigtsen.no