Anonymous functions have been around for a long time. And since WordPress now supports php 5.6 it can be safely used.
And appears to be allowed?
Personally I’m not a fan of anonymous functions in combination with WordPress actions and filters. My main concern is you can’t remove them once registered. How ever today I found a use case which was very usefull in combination with the use
My example:
<?php
/* Template name: some-template */
// Gather all data
$condition_for_title = true;
$h1_title_override = 'very heavy and complicated check';
// the H1 also needed as the <title>
add_filter( 'pre_get_document_title', function( $title ) use ($h1_title_override, $condition_for_title) {
if ($condition_for_title) {
return $h1_title_override;
}
return $title;
}, 20, 1 );
get_header();
// start body
?>
<h1><?php echo $h1_title_override ?>
Here I pass 2 variables h1_title_override and $condition_for_title which are created outside the function. In my case these where quite complicated and heavy checks. Of course I could put those in a function and cache the result. And call that check in the filter function. But still I need to check the current template before doing the function.
More traditional Example:
in functions.php
function complicated_check() {
// Gather all data
$condition_for_title = true;
$h1_title_override = 'very heavy and complicated check';
return [
'condition_for_title' => $condition_for_title,
'h1_title_override' => $h1_title_override,
];
}
function title_exception_for_template( $title ) {
if ( ! is_page_template('clean-template.php')) {
return $title;
}
$template_data = complicated_check();
if ( $template_data['condition_for_title'] ) {
return $template_data['h1_title_override'];
}
return $title;
}
add_filter( 'pre_get_document_title', 'title_exception_for_template', 20, 1 );
in clean-template.php
<?php
/* Template name: clean-template */
$template_data = complicated_check();
get_header();
// start body
?>
<h1><?php echo $template_data['h1_title_override'] ?>
Both these approaches do the same thing. But the more traditional way is a lot more code. Although it has cleaner template.
I probably won’t use this much. If the anonymous function was more complicated it will get hard to read.
But for this case I think it was neat that I could use this little feature.
