如何在Emacs 25中将Cx SPC本地绑定到Gud模式

Question

Similar to How to change GUD breakpoint keybinding to the old one but I would like to bind CTRL + x followed by SPACE to be gud-break .

What I have working (well it is a hack; keep reading) is:

  (define-key ctl-x-map " " 'gud-break)

but ctl-x-map is a global variable akin to the global map. And in fact, if I switch to another C++ buffer and type Ch k Cx SPC I get:

C-x SPC runs the command gud-break (found in global-map), which is an interactive compiled Lisp function.

It is bound to C-x SPC, C-x C-a C-b.

(gud-break ARG)

Set breakpoint at current line.

which means the global definition across all buffers is what was changed, which is not correct AFAIK.

Is there a way to "insert" or somehow affect the local key map for Cx, which I believe is gud-mode-map , because I want that binding to not be global for all C++ buffers. Eg, the global binding for CTRL + x followed by SPACE is rectangle-mark-mode .

Yes I realize the standard binding is Cx Ca Cb for gud-break , but that is asking for RSI.

Update #1

Since I need the local key map for gud-mode-map , this needs to be active only when I'm running a debugger. In my case, this is in C++ mode buffers, but my understanding is that gud-mode-map becomes active in those C++ mode buffers only during the debug session, and is removed from the key bindings when gud mode is finished.

Update #2

This did not work:

(define-key gud-mode-map [(control x ?\ )] 'gud-break) ;; <-- gave "Two bases given in one event" error too.
(define-key gud-mode-map (kbd "C-x SPC") 'gud-break) ;; <-- this does not work either.

Update #3

As an experiment, I commented out my define-key bindings in my hook I add to gud-gdb-mode-hook , reran gdb, then switched to the gud buffer (not the C++ source file) and typed Ch k Cx SPC I get this:

C-x SPC runs the command gud-break (found in gud-mode-map), which is
an interactive Lisp closure.

It is bound to <menu-bar> <debug> <break>, C-x SPC, C-c C-b, C-x C-a
C-b.

(gud-break ARG)

Set breakpoint at current line.

But then when I switch over to the C++ buffer that should also have the same bindings inserted temporarily (while gud mode is active), and then do the same thing I get this instead:

C-x SPC runs the command rectangle-mark-mode (found in global-map),
which is an interactive autoloaded compiled Lisp function in
'rect.el'.

It is bound to C-x SPC.

(rectangle-mark-mode &optional ARG)

Toggle the region as rectangular.
Activates the region if needed.  Only lasts until the region is deactivated.

Switching back to the gud buffer, and typing Ch m shows this:

Debugger mode defined in 'gud.el':
Major mode for interacting with an inferior debugger process.

   You start it up with one of the commands M-x gdb, M-x sdb, M-x dbx,
M-x perldb, M-x xdb, or M-x jdb.  Each entry point finishes by executing a
hook; 'gdb-mode-hook', 'sdb-mode-hook', 'dbx-mode-hook',
'perldb-mode-hook', 'xdb-mode-hook', or 'jdb-mode-hook' respectively.

After startup, the following commands are available in both the GUD
interaction buffer and any source buffer GUD visits due to a breakpoint stop
or step operation:

C-x SPC sets a breakpoint at the current file and line.  In the
GUD buffer, the current file and line are those of the last breakpoint or
step.  In a source buffer, they are the buffer's file and current line.

...

Notice the reference to Cx SPC above. It is as if they intended to bind Cx SPC but it did not work, or something is preventing it from being bound properly in that buffer when gud mode is entered.

Answer 1

I'm not exactly clear on what you want. But if you only want to redefine the key Cx SPC when the gud-mode-map is active, then tell define-key you want to use that map: (define-key gud-mode-map ...) .

Answer 2

I've chosen to give up on this altogether. using Cx SPC in the buffer is problematic anyhow. I noticed that the Cx Ca prefix that is used for the gud bindings are left in the C++ buffer even after gud finishes, so the gud mode is not cleaning up after itself anyhow.