Reinstate helper_alternate_class() function

[dregad]

Following the discussion in www.mantisbt.org/bugs/view.php?id=17437, this restores the helper_alternate_class() function previously removed by dhx.

The purpose is to avoid errors with plugins relying on this function following the upgrade.

To facilitate plugin authors' efforts in updating their code to use CSS for table row colors alternation, the function now triggers a deprecated warning.

Since displaying inline errors from within an html tag will mess with the output, a mechanism has been implemented to delay the printing of such errors, which are displayed in a block at the bottom of the page.

[rombert]

+1

[grangeway]

-1 to this - we should block plugins from being loaded if they are designed for a different version of Mantis:

We need to ensure that plugins are only loaded if they have been updated for the release of Mantis they are on.

So for example, if a plugin is designed for 1.2, it should work on 1.2.X releases ideally

But a plugin designed for 1.2 shouldn't load in 1.3 - in some cases there are Database changes or other changes that may require a user to update their plugin. Allowing a plugin designed for a completely different version of Mantis to run in a new version could lead to un-intended consequences (especially given the scope of changes between 1.2 and 1.3)

We started discussing this previously in http://www.mantisbt.org/bugs/view.php?id=17360

[dregad]

we should block plugins from being loaded if they are designed for a different version of Mantis

This is now implemented in PR #239.

However, since 1.3 is supposed to be a non-breaking (minor) version, I still think that this should be merged (with the deprecated warning), and the function killed in 2.x.

[dregad]

@vboctor your feedback on this would be appreciated

[vboctor]

I actually think having this deprecated method makes sense. It will enable us to make it obvious for ourselves and plugin developers when there are methods that are about to be deprecated and shouldn't be used. Even with the other pull request, we may still have plugins that specify a range and would benefit from this information.

I would expect this new error type would show in config_defaults_inc.php / manual as appropriate. Ideally the version range formats would also show in the developer's manual (though that is not part of this pull request).

+1.

[vboctor]

@dregad this PR is marked as one of the issues blocking 1.3, can you please finalize/merge.

[dregad]

Will do.

Need to open an issue to track the introduction of DEPRECATED error type.
==> http://www.mantisbt.org/bugs/view.php?id=17837

Note to self: update commit message to reflect new bug ID. Also add #17522 to 4bd7006

[dregad]

Rebased in preparation for merge

[dregad]

Here's how things looks like for a plugin relying on helper_alternate_class:

• rows colors alternate
• deprecated warnings are displayed at page bottom (only with $g_display_errors set to display them inline)