Rewrite rules should be flushed when you switch themes

[jorbin]

@nacin said so at WCMA, so here's a patch to do it.

Why should rewrite rules be flushed when switching themes?

I suppose in case a theme is using custom post types. But it seems that, like plugins, themes that need flushed rules should handle it themselves.

Replying to filosofo:

But it seems that, like plugins, themes that need flushed rules should handle it themselves.

Unfortunately, there's no activation hook for them to do so. (For example P2 uses an option to store whether rules have been flushed.) I suggested this in response to a question for how to handle things that add rewrite rules...

I don't think this patch will work, though, because the new theme isn't included on that pageload so the old rules will still be regenerated. Sounds to me that to do an activation hook for themes, we need to add an autoloaded option to keep track.

Adding an activation hook sounds like the best solution for this. We have switch_theme, which works on deactivation. Themes that add custom post types and taxonomies should be flushing the rewrite rules themselves.

+1 for theme activation hook.

resetting keywords since the attached patch will not work as intended.

If anyone would like to get this in for 3.1, there are a few days left to submit patches for enhancements before freeze.

This is done in 3.0 on wp-admin/themes.php. We should do this better, in conjunction with a real theme activation hook, in the future.

FYI, the jank was removed in 3.1. [17241]. Need to do this properly in 3.2.

Related: #7795