Re: Suggestion: Simple way to make conditional key bindings.

[Stefan Monnier]

>     One advantage (IMO) is that C-h k C-y will report yank or
>     yank-with-properties depending on the actual function taken if
>     you hit C-y.
> 
> If we use menu-item, what will C-h c say? 

Same thing (it runs the filter).

>       (define-key global-map "\C-y" 'yank-careful)
>       (defun yank-careful (...)
>       "Reinsert the last stretch of killed text, like `yank'.
>       Contrary to `yank' this function is careful to preserve some important
>       text properties when yanking tables."
>       ...)
> 
>     The advantage is that C-h k C-y doesn't just give you one of the two
>     bindings but a docstring that describes both.
> 
> I think that sometimes this will be better, but sometimes it will be
> better for C-h k to give the doc string for the specific command
> that will be executed.

Agreed.  But in the example he gave I think that a docstring that
describes the range of behavior rather than the specific command is
better, because you can't expect the user to know that the current
string is "special".

I think that whether the docstring should cover all the possible behaviors
or just the specific current one depends on how what the behavior depends on:
if it's very implicit and/or changes often the first is preferable.
This is the case for his example.

OTOH if it's explicit and/or doesn't change often, then the latter is
preferable.  This is the case (and the current behavior) for minor modes.


        Stefan