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Re: map-keymap doc not clear
Re: map-keymap doc not clear
Mon, 16 Jan 2006 18:10:03 -0500
Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (gnu/linux)
> If key sequence `C-x 4 f' is bound to command `find-file-other-window',
> then, IIUC, the events or keys here are `C-x', `4', and `k'. Is that what
> you mean?
> I guess that the bindings for these events correspond to the
> keymap that is the value of `ctl-x-map', the keymap that is the value of
> `ctl-x-4-map', and `find-file-other-window', respectively - is that the way
> it works?
Yes. If you apply map-keymap to the global-map, one of the calls will pass
"?C-x" as the `event' and ctl-x-map as the `binding'.
If you apply map-keymap to ctl-x-map, one of the calls will pass ?4 as the
`event' and `ctl-x-4-map' as the binding.
> The doc says that FUNCTION is called on the event (not on a multi-event key
> sequence) and on its binding, but I guess I'm unclear as to what the binding
> of such an event is.
I hope that clears it up a bit.
>> 2. I still have the question about whether FUNCTION is called for each
>> binding or each key sequence.
> I don't understand the question.
> I'm not sure what part you don't understand, or whether repeating it might
> help. Can you tell me what part you don't understand?
Give me some examples and ask me what they should do.
> The doc string uses "binding" to refer to the command (or the keymap etc.)
> that is bound to the key - that's not the same as the tuple (key . binding).
> I'm asking if it is correct that FUNCTION is called once for each such
> binding in KEYMAP.
Oh, I see. Yes there's an ambiguity: "binding" is sometimes used to refer
to the pair (KEY + COMMAND) and sometimes only to COMMAND. Which is meant
is normally clear from context.
E.g. in the case of map-keymap, if "Call FUNCTION for every binding in
KEYMAP" were to mean it's called once per command (or sub-keymap) in the
keymap, we have a problem: since each such command can be bound to several
key-sequences but the docstring says "FUNCTION is called with two arguments:
the event and its binding", that means that which `event' is passed is
unspecified, or arbitrarily chosen.
> I'm guessing that this might be incorrect, that, instead, FUNCTION is called
> once for each bound key, not once for each command (or keymap etc.) that is
> bound to a key. This makes a difference in case two keys are bound to the
> same command (or keymap). If FUNCTION is called for each binding, not each
> key, then which key (event) is supplied as the arg for a binding bound to
> more than one key?
> E.g given (key1 . binding) and (key2 . binding), which is called,
> (FUNCTION key1 binding) or (FUNCTION key2 binding)?
Exactly. Which is why it's clearly a bad interpretation of the meaning of
the docstring. Of course, the docstring shouldn't need to be
interpreted so carefully.
> I'm hoping you understand my confusion better now. If so, maybe you can
> propose some language that would make the behavior clearer to someone who
> might be confused in the same way as I.
Maybe you have some suggestion?
My proposition would be to just use:
Call FUNCTION for every event bound in KEYMAP.
FUNCTION is called with two arguments: the event and its binding.
If KEYMAP has a parent, the parent's bindings are included as well.
This works recursively: if the parent has itself a parent, then the
grandparent's bindings are also included and so on.
but it doesn't fix your confusion between key-sequences and just
single keys. I'm not sure how to improve it.
Re: map-keymap doc not clear, Richard M. Stallman, 2006/01/16