key binding only when in a given minor mode and a given major mode?

key binding only when in a given minor mode and a given major mode?

[Drew Adams]

I have a minor mode that binds some keys in its minor-mode map. In some
cases, these shadow global bindings. When the mode is turned off, the
minor-mode bindings are no longer in effect.

That works fine, but what happens when the binding I want to shadow is not a
global binding but a major-mode binding? What's a good way to create a
binding that will only be effective when in both a particular major mode and
a particular minor mode? When not in that minor mode, but still in the major
mode, I want the major-mode binding to be in effect, and when not in that
major mode, I want the global binding to be in effect.

For example, suppose I want to bind `g' in Info (major) mode to command
`foo-cmd' if and only if minor mode `foo' is turned on. I don't want to
affect global bindings or bindings in other modes. Turning `foo' off while
in Info should remove the binding of `g' to command `foo-cmd'. Turning `foo'
on or off while not in Info should have no effect on the binding of `g'.

All I can think of are these possibilities:

1. Bind the key in the minor-mode map to another command, `maybe-foo-cmd',
which tests the major mode and either calls `foo-cmd' or uses the global
binding of the key.

2. Bind the key in the major-mode map to another command, `maybe-foo-cmd',
which tests the minor mode and either calls `foo-cmd' or uses the major-mode
binding of the key.

#2 seems preferable, but I wonder if there isn't a better way to accomplish
this, without the intermediary of another command like `maybe-foo-cmd'. I
looked through the Elisp manual, but I didn't notice anything that might be
pertinent here. It looks like `minor-mode-overriding-map-alist' would be
almost what I need, but it does the opposite: it lets a major mode override
minor-mode maps.

Suggestions appreciated.

Re: key binding only when in a given minor mode and a given major mode?

[David Kastrup]

"Drew Adams" <drew.adams@oracle.com> writes:

> I have a minor mode that binds some keys in its minor-mode map. In some
> cases, these shadow global bindings. When the mode is turned off, the
> minor-mode bindings are no longer in effect.
>
> That works fine, but what happens when the binding I want to shadow
> is not a global binding but a major-mode binding? What's a good way
> to create a binding that will only be effective when in both a
> particular major mode and a particular minor mode? When not in that
> minor mode, but still in the major mode, I want the major-mode
> binding to be in effect, and when not in that major mode, I want the
> global binding to be in effect.

Uh, minor modes are by default local.  Are you using a global minor
mode for some reason?

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

RE: key binding only when in a given minor mode and a given majormode?

[Drew Adams]

    Uh, minor modes are by default local.  Are you using a global minor
    mode for some reason?
    
Uh, yes, I am. The reason is that I want it to be global ;-).

Re: key binding only when in a given minor mode and a given major mode?

[David Kastrup]

"Drew Adams" <drew.adams@oracle.com> writes:

> I have a minor mode that binds some keys in its minor-mode map. In some
> cases, these shadow global bindings. When the mode is turned off, the
> minor-mode bindings are no longer in effect.
>
> That works fine, but what happens when the binding I want to shadow is not a
> global binding but a major-mode binding? What's a good way to create a
> binding that will only be effective when in both a particular major mode and
> a particular minor mode? When not in that minor mode, but still in the major
> mode, I want the major-mode binding to be in effect, and when not in that
> major mode, I want the global binding to be in effect.
>
> For example, suppose I want to bind `g' in Info (major) mode to command
> `foo-cmd' if and only if minor mode `foo' is turned on. I don't want to
> affect global bindings or bindings in other modes. Turning `foo' off while
> in Info should remove the binding of `g' to command `foo-cmd'. Turning `foo'
> on or off while not in Info should have no effect on the binding of `g'.
>
> All I can think of are these possibilities:
>
> 1. Bind the key in the minor-mode map to another command, `maybe-foo-cmd',
> which tests the major mode and either calls `foo-cmd' or uses the global
> binding of the key.
>
> 2. Bind the key in the major-mode map to another command, `maybe-foo-cmd',
> which tests the minor mode and either calls `foo-cmd' or uses the major-mode
> binding of the key.
>
> #2 seems preferable, but I wonder if there isn't a better way to accomplish
> this, without the intermediary of another command like `maybe-foo-cmd'. I
> looked through the Elisp manual, but I didn't notice anything that might be
> pertinent here. It looks like `minor-mode-overriding-map-alist' would be
> almost what I need, but it does the opposite: it lets a major mode override
> minor-mode maps.

Well, so let your major mode override an empty minor-mode map.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum