Some array callables for WordPress

array-callables.php

<?php
function __array_append( $item ) {
	return function( $array ) use ( $item ) {
		$array[] = $item;
		return $array;
	};
}

function __array_set( $key, $value ) {
	return function( $array ) use ( $key, $value ) {
		$array[ $key ] = $value;
		return $array;
	}
}

// Examples:
add_filter( 'body_class', __array_append( 'foo' ) );
add_filter( 'shortcode_atts_gallery', __array_set( 'columns', 4 ) );