Setting autosave interval without core editing?

Hi,

I do realize this can be achieved easily by editing wp-config.php, but core-editing is just a bad idea, in general, so maybe you can help me figure this out.

I’m interested in setting functionality constants (ie, WP_POST_REVISIONS) in a theme’s functions file, but can’t find the right hook. I started by adding the action to ‘init’, but that’s too late; this produces a warning that the constants are already defined.

After looking at the wp-settings.php file, I find this at lines 212-215:

do_action( 'plugins_loaded' );

// Define constants which affect functionality if not already defined.
wp_functionality_constants( );

So, this is where the relevant constants are set. Looking at the function that does the work (default-constants.php, lines 261-262) it shows that these constants are indeed pluggable as such:

if ( !defined('WP_POST_REVISIONS') )
	define('WP_POST_REVISIONS', true);

Now, as the ‘plugins_loaded’ action is run right before these constants are set, I tried to place my action there, but while this didn’t produce an error or warning onscreen, the (theme-set?) constants seemed to be ignored. Echoing out the constants in the footer showed that they were still using the WP defaults, as set in default-constants.php.

Here’s what I’m using in functions.php:

function resetAutosave()
{
    define('AUTOSAVE_INTERVAL', 300);
}
add_action('plugins_loaded', 'resetAutosave', 0);

What am I missing here?

Thanks for any insight!