[wordpress] 输出一个过滤器绑定的方法

参考了WordPress: How do I get all the registered functions for 'the_content' filter,

function print_filters_for( $hook = '' ) {
    global $wp_filter;
    if( empty( $hook ) || !isset( $wp_filter[$hook] ) )
        return;

    print '<pre>';
    print_r( $wp_filter[$hook] );
    print '</pre>';
}

调用它时，像

print_filters_for('determine_current_user');