Re: Interesting problem: eval-after-load and local variables

[Kevin Rodgers <kevin.d.rodgers@gmail.com>]

On 10/17/12 2:32 AM, Sebastien Vauban wrote:
> Kevin Rodgers wrote:
...
>> In general, it is not necessary to load a library before customizing its global
>> options.  You should get the desired effect with just:
>>
>> (setq time-stamp-format "%:y-%02m-%02d %3a %02H:%02M %u")
>
> I know. And this is a very somewhat ridiculous example. But, for speed and
> clarity of my .emacs, I've generally put all customs inside an
> eval-after-load. A setq is certainly not time-taker, certainly not when alone,
> but I've applied the same principal to many other blocks of customs.

I don't see how the eval-after-load boilerplate provides any speed or clarity.

...

>> I don't see how, since those variables aren't autoloaded.  (Their autoload
>> cookies only result in the safe-local-variable property being dumped into the
>> emacs executable for each symbol.)  I suspect you have enabled time stamp as
>> documented in the Emacs manual:
>>
>>     Then add the hook function `time-stamp' to the hook
>> `before-save-hook'; that hook function will automatically update the
>> time stamp, inserting the current date and time when you save the file.
>>
>> (The function time-stamp is autoloaded.)
>
> You're absolutely right!  I described the correct effect, but not the right
> cause...
...
>> Actually, I think the file local variables are applied and then overridden by
>> the eval-after-load form (but only for the first file that you save).
>
> Your explanation must be right. But my question was more general, in the
> sense: is this the behavior one would expect?  Or *should local vars triumph
> over the setq done in the eval-after-load?*

We should expect file local variables and eval-after-load to work as documented
-- and they do.  It is our responsibility to use them correctly -- but you used
eval-after-load unnecessarily, without considering the context.

>> Do other files with time stamp templates work as intended?
>
> I'll check (but I've already applied the fix suggested by Michael).  I guess
> the answer is yes.
...
>> I think you should either skip the eval-after-load boilerplate
>
> As said, for this example: you're definitively right. It's kind of useless.
>
>> or use setq-default in the eval-after-load form as suggested by Michael.
>
> Can I use setq-default with whichever var?  I guess not. But am I right?

You _can_ use setq-default on any variable, to ensure that you are setting its
global binding and not the current buffer-local binding (if any).

-- 
Kevin Rodgers
Denver, Colorado, USA