global-company-mode and company-mode

global-company-mode and company-mode

[wilnerthomas--- via Users list for the GNU Emacs text editor]

I do not understand how to enable `company-mode'.  Because there is (company-mode 1)
and `(add-hook 'after-init-hook 'global-company-mode)'.

What is the difference between the two.  Why 'after-init-hook is used, cannot there just be
(global-company-mode 1)?

When using `add-hook', how would I disable `global-company-mode' later?

Re: global-company-mode and company-mode

[thibaut.verron]

On 02/08/2022 12:26, wilnerthomas--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
> 
> I do not understand how to enable `company-mode'.  Because there is (company-mode 1)
> and `(add-hook 'after-init-hook 'global-company-mode)'.
> 
> What is the difference between the two.  

(company-mode 1) only turns the mode on in the current buffer, (global-company-mode 1) turns it on in every existing buffer, and will turn it on in every future buffer (except for buffers not visiting a file and with the fundamental-mode).

https://www.gnu.org/software/emacs/manual/html_node/elisp/Defining-Minor-Modes.html

> Why 'after-init-hook is used, cannot there just be
> (global-company-mode 1)?

I am not sure, but I suspect it is to make sure that all packages which might change the way company-mode works are already loaded at the time of activation.

But then again, the main effect of (global-company-mode 1) at that point is to tell future buffers to activate company-mode, which would be after initialization anyway. 
Even the *scratch* buffer (usually the only editable buffer created at initialization) should be in fundamental-mode at the time of running of the hook, so it isn't affected by global-company-mode.

So the two calls might not be strictly equivalent, but I believe that they would be indistinguishable in most use-cases.


> 
> When using `add-hook', how would I disable `global-company-mode' later?
> 

The hook is run only once, when starting emacs, so it doesn't matter in a running emacs.
Just call (global-company-mode -1) to disable it later. Note that it should also disable company-mode in all buffers where the global setting was applied (and not overridden by a local (company-mode 1)). (I think, at least. I always end up confused by the semantics of disabling global vs local modes.)

Best wishes,
Thibaut

Re: global-company-mode and company-mode

[wilnerthomas--- via Users list for the GNU Emacs text editor]

Aug 2, 2022, 11:09 by thibaut.verron@gmail.com:

> On 02/08/2022 12:26, wilnerthomas--- via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org> wrote:
>
>>
>> I do not understand how to enable `company-mode'.  Because there is (company-mode 1)
>> and `(add-hook 'after-init-hook 'global-company-mode)'.
>>
> What is the difference between the two.  
> (company-mode 1) only turns the mode on in the current buffer, (global-company-mode 1) turns it on in every existing buffer, and will turn it on in every future buffer (except for buffers not visiting a file and with the fundamental-mode).
>
> https://www.gnu.org/software/emacs/manual/html_node/elisp/Defining-Minor-Modes.html
>
>> Why 'after-init-hook is used, cannot there just be
>> (global-company-mode 1)?
>>
>
> I am not sure, but I suspect it is to make sure that all packages which might change the way company-mode works are already loaded at the time of activation.
>
> But then again, the main effect of (global-company-mode 1) at that point is to tell future buffers to activate company-mode, which would be after initialization anyway. Even the *scratch* buffer (usually the only editable buffer created at initialization) should be in fundamental-mode at the time of running of the hook, so it isn't affected by global-company-mode.
>
> So the two calls might not be strictly equivalent, but I believe that they would be indistinguishable in most use-cases.
>
>
>>
>> When using `add-hook', how would I disable `global-company-mode' later?
>>
>
> The hook is run only once, when starting emacs, so it doesn't matter in a running emacs.
> Just call (global-company-mode -1) to disable it later. Note that it should also disable company-mode in all buffers where the global setting was applied (and not overridden by a local (company-mode 1)). (I think, at least. I always end up confused by the semantics of disabling global vs local modes.)
>
Right.  Is there the command (global-company-mode -1) available?  What if I want to enable global-company-mode, would I use the hook?

Re: global-company-mode and company-mode

[Dmitry Gutov]

On 02.08.2022 14:15, wilnerthomas--- via Users list for the GNU Emacs 
text editor wrote:
> Right.  Is there the command (global-company-mode -1) available?  What if I want to enable global-company-mode, would I use the hook?

Just 'M-x global-company-mode' in both cases. It toggles.

Re: global-company-mode and company-mode

[Thibaut Verron]

On 02/08/2022 13:23, Dmitry Gutov wrote:
> On 02.08.2022 14:15, wilnerthomas--- via Users list for the GNU Emacs 
> text editor wrote:
>> Right.  Is there the command (global-company-mode -1) available?  
>> What if I want to enable global-company-mode, would I use the hook?
>
> Just 'M-x global-company-mode' in both cases. It toggles.

Or evaluate (global-company-mode 1), or customize the value of the 
variable global-company-mode (with M-x customize-group).

Really, the after-init-hook should only run when starting emacs, so 
changing it will only have an effect when restarting emacs (provided 
that the changes are saved between sessions), or using run-hook manually 
(but this might have undesirable side-effects with whatever else is done 
in the hook). It is really not meant to make changes to the status of a 
running emacs.

Best wishes,

Thibaut