How do you check if a WordPress template file exist?

Question

Is there a native function to check if a theme a template file. For instance, if a theme is not using the 'home.php' file, then execute some code...

Answer 1

So I would add to the Answer the following:

function foo_function() {
    $located = locate_template( 'home.php' );
     if ( !empty( $located ) ) {
          // 'home.php' found in Theme, do something
     }
}
add_action('init', 'foo_function');
// remember to change both of the parameters above, first one for where you want the
// action to happen and the second one the name of the function declared

As @Chip Bennett, said it will check both TEMPLATEPATH and STYLESHEETPATH, but I would append the code to a hook instead of just putting it in the functions.php file.

But's up to you.

Answer 2

Any reason locate_template() (Codex ref) wouldn't work?

if ( '' != locate_template( 'home.php' ) ) {
     // 'home.php' found in Theme, do something
}

Note that locate_template() will check both TEMPLATEPATH and STYLESHEETPATH, so it works for both a stand-alone Theme and a Child Theme.