Re: [elpa] master 9173a44 1/2: [Fix #12] Don't autodisable beacon on hl-line-mode

[Stefan Monnier <monnier@iro.umontreal.ca>]

>> A custom var shouldn't be modified programmatically.
> Out of curiosity: why?

Because Custom then can't change those chunks of code in order to get
the desired value.

E.g. there's a (setq foo 4) somewhere and the user uses Custom to set
`foo' to 3.  How is customize-save going to make sure that next time
Emacs starts, `foo' will be set to 3 rather than 4?

> I setq all my defcustoms, since I don't use Customize.

As a user you're free not to (setq foo 4) in your ~/.emacs, of course,
and since you don't use Custom, Custom won't have to try and set `foo',
so everything's fine.  And if you do try and set `foo' via Custom, then
Custom will rightfully complain and you'll just get what you deserve.

But as a package author, such a decision is very different: using (setq
foo 4) or add-hook in your package means that all your users will have
problems if they try to set this var via Custom.


        Stefan