compileLessVariables.php

<?php
function compiler_action( $options, $css, $changed_values ) {
        
        $keys   = array(
            'header_color',
            'header_footer_color'
        );
        $compile = false;
        foreach ( $changed_values as $key => $value ) {
            if ( in_array( $key, $keys ) ) {
                $compile = true;
            }
        }
        if ($compile) {
            $string = "";
            foreach ( $options as $key => $value ) {
                if ( in_array( $key, $keys ) ) {
                    $string .= "@" . $key . ':' . $value . ';';
                }
            }
            // RUN LESS COMPILER
        }
        
        
        echo '<h1>The compiler hook has run!</h1>';
        echo "<pre>";
        print_r( $changed_values ); // Values that have changed since the last save
        echo "</pre>";
        //print_r($options); //Option values
        //print_r($css); // Compiler selector CSS values  compiler => array( CSS SELECTORS )
    }