Re: global-company-mode and company-mode

[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.)

Best wishes,
Thibaut