[Mediawiki-l] Default path settings

[Ichiro Watanabe]

> Platonides wrote:
> No. Only those (and all of them) that contain another $wgVariable into
> its default value.

OK, that makes sense now, thanks for the explanation.

> I think it is only confusing if you look at DefaultSettings expecting to
> see the default there and can't find it.

I think that's a separate issue, but it certainly is making things worse.

Let's see if I understand correctly:
1. DefaultSettings.php is run. Here all variables are set to the
default values, *except* those that are dependent on other variables,
which are set to false (as a placeholder).
2. LocalSettings.php is run. Here users can set any variables to
whatever they like.
3. Setup.php is run. Here any variables that are dependent on other
variables *and* that have not been customised in LocalSettings.php are
set to their default value, based on other variables that may or may
not have been changed in LocalSettings.php

If this is correct, I think the documentation does not make it clear.
Here are the changes I propose.

DefaultSettings.php, line 10, reads

 * Note that since all these string interpolations are expanded
 * before LocalSettings is included, if you localize something
 * like $wgScriptPath, you must also localize everything that
 * depends on it.

If my understanding is correct, then this is not only confusing, it is
wrong. I propose something like the following instead

 * In this file, variables whose default values depend on other
 * variables (for example $wgStylePath, which defaults to
 * "{$wgScriptPath}/skins") are set to false.
 * The sequence of execution is DefaultSettings.php >
LocalSettings.php > Setup.php
 * The actual default value of these variables will only be set in Setup.php,
 * taking into account any custom settings performed in LocalSettings.php.

Also in DefaultSettings.php, I propose changing these comments

    $wgStylePath   = false; ///< defaults to "{$wgScriptPath}/skins"

to something like

    $wgStylePath   = false; ///< will default to
"{$wgScriptPath}/skins" in Setup.php

Here there is a minor point of mantainability, in that if the default
value changes we need to change it both in Setup.php,
DefaultSettings.php and on the Manual page in MediaWiki's wiki. Let's
sidestep this issue for now.

Then there are the Manual pages. I propose the following note is
included in the Manual pages *of each variable* that has this
behaviour.

<small>(Note: Since the defult value of this variable depends on other
variables, such default value is set in Setup.php, after
LocalSettings.php is executed)</small>

If there are no objections, I'm happy to apply the changes to the
Manual. For the code comments, please let me know how to submit the
patches.
Thanks.