Re: loading spam.el and gnus-registry.el with set variables only

[Reiner Steib <4.uce.03.r.s@nurfuerspam.de>]

On Thu, Oct 09 2003, Ted Zlatanov wrote:

> On Tue, 07 Oct 2003, tzz@lifelogs.com wrote:
>
>> Speaking for those two packages, it has been the #1 problem that
>> people have to set a variable (gnus-registry-install or
>> spam-install-hooks) and then do a require of the .el file.  How
>> could I make it so setting any of the two variables above will load
>> its appropriate package when Gnus is loaded?

[Disclaimer: I'm not familiar with gnus-registry.el and spam*.el
internals.]

The importance of the order seems quite fragile to me, isn't it?
_Normally_ (counter-examples follow below) I'd expect that changing a
variable has some effect, no matter if a corresponding package is
loaded before or after setting the variable.

I'd use functions, say `gnus-registry-initialize' and
`spam-initialize' (or -install?) and autoload those functions:

;;;###autoload
(defun gnus-registry-initialize ...)

;;;###autoload
(defun spam-initialize ...)

Probably, you should also add autoload cookies to the relevant
variables.  E.g. in my current setup, gnus-registry isn't loaded, so I
cannot customize `gnus-registry-install'.

> Anyone?  If this is not yet standardized in Gnus, I'll go ahead and
> put some code in gnus.el that will look in a table of symbols and if
> the symbol is set, will load the corresponding library.  I just want
> to make sure I'm not missing something obvious.

I doubt that we have a Gnus-specific standard/convention.  Maybe
there's something in the Emacs or Elisp manual?

Maybe, instead of ...-initialize, using a minor mode is better?
Grepping the Emacs lisp sources for "no effect" gives some examples:

,----[ C-h v normal-erase-is-backspace RET ]
| normal-erase-is-backspace's value is t
| [...]
| Setting this variable with setq doesn't take effect.  Programmatically,
| call `normal-erase-is-backspace-mode' (which see) instead.
| 
| You can customize this variable.
| 
| Defined in `simple'.
`----

,----[ C-h v utf-translate-cjk-mode RET (in CVS HEAD) ]
| utf-translate-cjk-mode's value is nil
| 
| Non-nil if Utf-Translate-Cjk mode is enabled.
| See the command `utf-translate-cjk-mode' for a description of this
| minor-mode.
| Setting this variable directly does not take effect;
| use either M-x customize or the function `utf-translate-cjk-mode'.
| 
| You can customize this variable.
| 
| Defined in `international/utf-8'.
`----

See the ":set" and ":initialize" keyword of `defcustom'.

Bye, Reiner.
-- 
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      (o o)
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