defcustom problem with packages (user error?)

defcustom problem with packages (user error?)

[Elias Mårtenson]

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In preparation for the eventual inclusion of gnu-apl-mode into ELPA, I
decided to ensure that the new-user experience is as smooth as possible. So
I started out with a minimal Emacs configuration and loaded my package from
MELPA (which is where it's located currently).

The following is the minimal configuration I started out with:

    (custom-set-variables
      ;; ....
      )
    (custom-set-faces
      ;; ...
      )
    (require 'package)
    (add-to-list 'package-archives '("elpa" . "http://tromey.com/elpa/"))
    (add-to-list 'package-archives '("marmalade" . "
http://marmalade-repo.org/packages/"))
    (add-to-list 'package-archives '("melpa" . "
http://melpa.milkbox.net/packages/"))
    (package-initialize)

Now, to make a long story short, here's the problem I encountered:

Given the configuration above, and gnu-apl-mode being the only package
loaded, I am unable to use the customisation framework to set any
variables. I mean, the variables can be customised and all, but the changes
become overridden as soon as `package-initialize' is called.

The workaround, of course, is to call `package-initialize' *before* the
call to `custom-set-variables'. However, this is not made clear anywhere.
That said, I'm not sure if there is a problem with the package, or this is
the way things are supposed to work.

So I guess my question is this: Did I make a mistake in developing the
package? If so, then is the proper way documented anywhere? And if my
package is correct, then why does the package loading override the default
values set by `custom-set-variables'?

If anyone is willing to take a look at the package, the source is available
at https://github.com/lokedhs/gnu-apl-mode

Regards,
Elias

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Re: defcustom problem with packages (user error?)

[Artur Malabarba]

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I'm not sure if that's the cause of your problem, but you don't need to
autoload all those defcustom s.
Just autoload the entry functions.

Artur Malabarba

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Re: defcustom problem with packages (user error?)

[Stefan Monnier]

> I'm not sure if that's the cause of your problem, but you don't need to
> autoload all those defcustom s.
> Just autoload the entry functions.

Oh, indeed, autoloading variables is generally a bad idea.  And it could
explain the behavior.  I haven't seen such problem until now, but it's
probably because such autoloads are rare.  So maybe we should document
it more prominently.


        Stefan

Re: defcustom problem with packages (user error?)

[Elias Mårtenson]

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On 12 November 2014 22:45, Stefan Monnier <monnier@iro.umontreal.ca> wrote:

> > I'm not sure if that's the cause of your problem, but you don't need to
> > autoload all those defcustom s.
> > Just autoload the entry functions.
>
> Oh, indeed, autoloading variables is generally a bad idea.  And it could
> explain the behavior.  I haven't seen such problem until now, but it's
> probably because such autoloads are rare.  So maybe we should document
> it more prominently.
>

Thank you. I made this change and indeed now it works better.

That said, if it's not a good idea to autoload customisable variables, then
what is the purpose of `custom-autoload'? This is what gets inserted into
gnu-apl-mode-autoloads.el.

Regards,
Elias

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Re: defcustom problem with packages (user error?)

[Stefan Monnier]

> That said, if it's not a good idea to autoload customisable variables, then
> what is the purpose of `custom-autoload'? This is what gets inserted into
> gnu-apl-mode-autoloads.el.

Some variables are "autoloaded", which basically means their definition
is copied to the autoloads file.  So far this has mostly been used for
lisp/loaddefs.el, i.e. int he case for the "autoloads" file gets loaded
once and forall during the dump process, long before the user's .emacs
and customizations can be involved.

Such autoloaded variables are generally a bad idea, but occasionally
they're useful so that other packages can use the var's value without
having to `require' the package where the var happens to be declared.

This said, most of those autoloaded variables are mistakes that we live
with because once it's autoloaded, it's predefined and hence packages
and .emacs files out there rely on the variable being always defined,
and de-autoloading it would break backward compatibility.

The custom-autoload thingy exists so that autoloaded custom vars don't
cost as much as if the full defcustom was copied into the loaddefs.el
file, IIRC.


        Stefan