Re: On keybindings and the slow erosion of help's utility

>> Say we have:
>>
>>     (keymap-global-set "TAB" #'my-foo)
>>     (keymap-set foo-mode-map "TAB" (make-partial-binding #'my-condition #'my-bar))
>>
>> Then `(key-binding "TAB")` in Foo mode would return something like
>>
>>     #f(composite-command #f(partial-binding my-condition my-bar) my-foo)
>>
>> So `my-condition` is not executed during keymap lookup but only during
>> command execution (so we don't need to worry about side-effects during
>> keymap lookups, tho we may still worry about them if we wan to run
>> `my-condition` during `C-h k` to whether we'd run `my-foo` or `my-bar`).
>>
>> Calling `composite-command` could look inside the `partial-binding`
>> command, tho a more generic approach would be for `composite-command` to
>> just call its first command with a "continuation argument" which is
>> the second command so it doesn't need to know about `partial-binding`.
>
> What if none of the `partial-binding's match?

If the last command is also a partial binding and it doesn't match, then
we can do something similar to calling `undefined`, tho maybe with
a tweaked message.  I don't see any difficulty here.  Am I missing something?

>> An important question is what to do with
>>
>>     (keymap-set foo-mode-map "TAB" (make-partial-binding #'my-condition1 #'my-bar1))
>>     (keymap-set foo-mode-map "TAB" (make-partial-binding #'my-condition2 #'my-bar2))
>>     (keymap-set foo-mode-map "TAB" (make-partial-binding #'my-condition1 #'my-bar3))
>>
>> should each call completely override the previous (so after those three
>> calls we have just a single partial binding that uses `my-bar3` when
>> `my-condition1` is true)?  Or should we just accumulate them (if so,
>> how do we remove a partial binding without removing them all)?
>> Or should the third call override the first but not the second (and presumably
>> allow `(keymap-set ...(make-partial-binding #'my-condition1 nil))`
>> to remove one of the partial bindings)?
>>
>> The third option sounds more flexible, but it requires more changes in
>> the `keymap.c` code.
>
> IMHO, the best approach is to make the full "partial-binding" named and the
> each condition also named (as in my suggestion with :name). I described
> examples earlier. I think that exactly the same structure can be used to
> manipulate the conditions. (I hope what I said in this paragraph makes sense)

I'm afraid I don't understand how what you say relates to what I said.

>> Also, in the above I assume that we're not interested in something like
>>     (keymap-set foo-mode-map "TAB" (make-partial-binding #'my-condition1 my-keymap))
> I am not sure why we need to introduce such a limitation vs. what I proposed.

Because what I'm describing moves the execution of the conditions to the
moment we run the command, rather than the keymap-lookup, so it's late
to do further key processing.

Strictly speaking, it would be possible, e.g. to call `popup-menu` after
evaluating the conditions if the chosen option is a keymap, but it
wouldn't integrate as well into the command loop and things like `C-h k`.


=== Stefan