Registers a filter callback that automatically removes itself after being called once. The filter only modifies the value for a single pass, then deregisters itself. Replaces the deprecated add_self_removing_filter().
Parameters
| Parameter | Type | Description |
|---|---|---|
$filter | string | The WordPress filter hook to register on. |
$callback | callable | The callback to run once. |
$priority | int | Hook priority. Default 10. |
$args | int | Number of arguments. Default 1. |
Return value
bool — true on success.
Usage
\Groundhogg\add_filter_use_once( 'groundhogg/email/subject', function( $subject ) {
return 'One-time override: ' . $subject;
} );
Example
Here’s a pseudo code example for a hypothetical per-contact subject line override.
add_action( 'groundhogg/broadcast/before', 'my_plugin_maybe_override_subject', 10, 3 );
/**
* Override the subject line for contacts in the B variant of an A/B test.
*
* @param \Groundhogg\Broadcast $broadcast
* @param \Groundhogg\Contact $contact
* @param \Groundhogg\Event $event
*
* @return void
*/
function my_plugin_maybe_override_subject( $broadcast, $contact, $event ) {
if ( ! $contact->has_tag( 'ab-test-group-b' ) ) {
return;
}
\Groundhogg\add_filter_use_once( 'groundhogg/email/subject', function( $subject ) {
return '[Special offer] ' . $subject;
} );
}
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