WordPress Functions File

  • Essentially operates like a plugin.
  • Applies only to the theme it is included in.
  • Is not single purpose like most plugins.
  • If a child theme has a functions.php it is loaded before the parent theme’s functions.php. The latter’s functions are still utilized where functions have not been defined in the former.
  • Setup
    • For functions use a namespace preface, e.g., my_theme_function.
    • add_theme_support( ‘automatic-feed-links’ ); – Adds post and comment RSS feeds automatically.
    • add_theme_support( ‘post-thumbnails’ );
    • add_theme_support( ‘post-formats’, array( ‘aside’, ‘gallery’, ‘quote’, ‘image’, ‘video’ ) );
    • register_nav_menus( array (
           ‘primary’ => __( ‘Primary Menu’, ‘myfirsttheme’ ),
      ‘secondary’ => __( ‘Secondary Menu’, ‘myfirsttheme’ )
      ) );


      • Allows for custom menus, array only necessary if theme is to support multiple menus.
    • Need to add this function as an action so it actually loads:
      add_action( ‘after_setup_theme’, ‘myfirsttheme_setup’ );
    • load_theme_text_domain() – Used to load additional languages.
    • $content_width – Determines the maximum width of any page/post.

Pluggable Functions

  • Functions for which WordPress includes a default that is only utilized if a function has not otherwise been created.
  • See wp-includes/pluggable.php