Defining key onto copied global map problem

Defining key onto copied global map problem

[Tomohiro MATSUYAMA]

Hi, all

I faced a problem when I define a key onto the copied global map.

After executing following code:

    (define-key (copy-keymap (current-global-map)) (kbd "M-c") 'ignore)

"M-c" won't work and just ignores.
I expected that "M-c" just works as defined in (current-global-map).

I'm using:
GNU Emacs 23.0.60.1 (i386-apple-darwin9.6.0, NS apple-appkit-949.43)
of 2009-01-27 on macbook.local

Regards,

MATSUYAMA Tomohiro

Re: Defining key onto copied global map problem

[Stefan Monnier]

>     (define-key (copy-keymap (current-global-map)) (kbd "M-c") 'ignore)

This creates a new keymap (of same content as the global map), modifies
it and then throws it away.


        Stefan

Re: Defining key onto copied global map problem

[David Reitter]

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On 24 Feb 2009, at 17:14, Stefan Monnier wrote:

>>    (define-key (copy-keymap (current-global-map)) (kbd "M-c")  
>> 'ignore)
>
> This creates a new keymap (of same content as the global map),  
> modifies
> it and then throws it away.

Which is why changing the copy of the keymap should have no effect -  
but it does.  I reproduce on Emacs 22.

Note that

   (define-key (copy-keymap (current-global-map)) (kbd "x") 'ignore)

works as expected, i.e. it does nothing.

"x" is in my global key-map,  while M-c isn't bound there.

I also tried something like

(setcdr  (copy-keymap (current-global-map)) '(foo))

which doesn't do anything to the global keymap either, so failing to  
copy the tail isn't the problem.

Further, note that the M-c binding doesn't show up in the original  
global map after the define-key call above; however, the binding  
becomes effective.



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Re: Defining key onto copied global map problem

[Miles Bader]

David Reitter <david.reitter@gmail.com> writes:
>>>    (define-key (copy-keymap (current-global-map)) (kbd "M-c") 'ignore)
>
> Which is why changing the copy of the keymap should have no effect - 
> but it does.  I reproduce on Emacs 22.
>
> Note that
>   (define-key (copy-keymap (current-global-map)) (kbd "x") 'ignore)
> works as expected, i.e. it does nothing.

I think the reason is that global meta bindings are looked up in the
ESC-prefix map, which is referenced in the top-level keymap using a
symbolic reference, not as an embedded keymap.

Even if copy-keymap recursively copies embedded keymaps, it does not
seem to recursively copy such symbolic references (which makes sense I
suppose).

(lookup-key (current-global-map) "\e") => ESC-prefix

-Miles

-- 
Patience, n. A minor form of despair, disguised as a virtue.

Re: Defining key onto copied global map problem

[Stefan Monnier]

> Even if copy-keymap recursively copies embedded keymaps, it does not
> seem to recursively copy such symbolic references (which makes sense I
> suppose).

> (lookup-key (current-global-map) "\e") => ESC-prefix

Indeed.


        Stefan