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Re: minor mode map question
From: |
Stefan Monnier |
Subject: |
Re: minor mode map question |
Date: |
Mon, 26 Feb 2007 15:09:34 -0500 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.0.92 (gnu/linux) |
> I wish that you could provide, as the cdr of an entry to
> `minor-mode-map-alist', an expression to be evaled to a keymap value, or
> perhaps a function that is called to return a keymap value. That would
> obviate needing to delete and re-add an entry, just to ensure that the alist
> is up-to-date whenever the keymap changes. It seems a bit weird to me that
> `minor-mode-map-alist' is so static, given how dynamic Emacs is otherwise.
> Why not use a keymap-valued variable or keymap-returning function here,
> instead of an actual keymap?
A keymap-valued variable is quite doable.
But something more dynamic is slightly tricky because the code tries to only
allocate memory *after* processing *one* key. The reason is that in case we
run out of memory, we still want to guarantee progress (or something like
that).
Basically we want to avoid something like:
1 - prepare to read a key: fetch the active keymaps.
2 - oops, running out of memory while doing that, let's signal an error.
3 - unhandled error, let's go back to the toplevel (i.e. to point 1).
I'm not sure how important it is to avoid such a freeze, since the
alternative is "read a key, signal an error, read a key, signal an error",
but the code does go through some extra trouble for this.
Stefan