Update filter.php for backward compatibility

[michael-milette]

This makes the plugin backward compatible with versions of Moodle up to 4.5.

[michael-milette]

Addresses a compatibility issue with versions of Moodle up to 4.4 as described on the following pages:

https://moodle.org/mod/forum/discuss.php?d=462953

and

https://moodle.org/mod/forum/discuss.php?d=462961

Best regards,

Michael Milette

[iarenaza]

Humm, we had that before, and I removed it. And as I commented in issue #54, the code works just fine in Moodle 4.1.13 (the version one of the error reporters is using) and 4.1.14+ (the one tested by the CI matrix when I last pushed the changes). As long as your PHP or Moodle caches (I don't know which one caches the classes paths) is not stale.

The problem with your proposed PR is that, as stated in commit 35befeb, "moodle-plugin-ci validate" insists on finding class filter_multilang2 in file filter.php. But the class aliasing construct is not recognized by the PHP parser used by moodle-plugin-ci (and adding that support is a rather major effort, believe me, I tried and failed miserably 😄).

Which means that, if we apply your PR, we cannot use moodle-plugin-ci validate in the CI pipeline (or we have to ignore its error output, as the initial PR from @lucaboesch did). Which is a major drawback IMHO.

I'm not completely sure if adding a use \filter_multilang2\text_filter at the top of the file would solve things in this case, to be honest.

[iarenaza]

Given that hopefully moodle-plugin-ci will be fixed soon with moodlehq/moodle-plugin-ci#326, I'm going to apply this PR.