How to tell if a script is being executed from a plugin, a theme or a child theme in WordPress?

Question

I have a framework for WordPress that can be embedded into either a plugin, a theme or a child theme. In order to return proper URLs, the script needs to determine from where it is being executed.

I believe I could do something like matching __FILE__ against:

• get_template_directory_uri() (theme),
• get_stylesheet_directory_uri() (theme or child theme), or
• plugin_dir_url( __FILE__ ) (plugin)

Is there a better, more reliable approach? Any any case, how would I go about it?

Answer 1

This function will return a string indicating where it is called from. The possible return values are plugin, mu-plugin, child-theme, theme, or FALSE if it is not in a theme or plugin.

When using this function, always pass __DIR__ as the parameter, example: where_am_i(__DIR__).

/**
 * @param string $directory always __DIR__
 */
function where_am_i($directory) {
    $current_directory = forward_slashes($directory);
    $plugins_directory = forward_slashes(WP_PLUGIN_DIR);
    $mu_plugins_directory = forward_slashes(WPMU_PLUGIN_DIR);
    $themes_directory = forward_slashes(get_theme_root());

    if ( strpos ( $current_directory, $plugins_directory ) !== FALSE ) {
        $location = 'plugin';

    } elseif ( strpos ( $current_directory, $mu_plugins_directory ) !== FALSE ) {
        $location = 'mu-plugin';

    } elseif ( strpos ( $current_directory, $themes_directory ) !== FALSE ) {
        // Script is in a theme, determine if parent or child
        $stylesheet_directory = forward_slashes(get_stylesheet_directory());

        if ( is_child_theme() && ( strpos ( $current_directory, $stylesheet_directory ) !== FALSE ) ) {
            $location = 'child-theme';
        } else {
            $location = 'theme';
        }

    } else {
        // not in a theme or plugin
        $location = FALSE;
    }

    return $location;
}

/**
 * Handle Windows paths
 */
function forward_slashes($string) {
    return str_replace('\\', '/', $string);
}

The following function, where_am_i_dir(), will give you the directory structure of the location it was called from, but omit */wp-content/{$subdir}. If it was called from /wp-content/themes/twentyfourteen/libs/script.php it will return /twentyfourteen/libs (if you want it to return with a trailing slash you can concatenate one to $directory when the slashes are filterd).

The first parameter is the return value from where_am_i() and the second parameter is always __DIR__. Example: where_am_i_dir($location, __DIR__).

/**
 * @param string $location return from where_am_i()
 * @param string $directory always __DIR__
 */
function where_am_i_dir($location, $directory) {
    if ($location == 'plugin') {
        $subdirectory_name = '/plugins';

    } elseif ($location == 'mu-plugin') {
        $subdirectory_name = '/mu-plugins';

    } elseif ($location == 'theme' || $location == 'child-theme') {
        $subdirectory_name = '/themes';

    } else {
        return FALSE;
    }

    $directory = forward_slashes($directory);
    $wp_content_directory = forward_slashes(WP_CONTENT_DIR) . $subdirectory_name;

    return str_replace($wp_content_directory, '', $directory);
}

If you were interested you could probably combine where_am_i() and where_am_i_dir() into one function that returns an array with both values.

Answer 2

This answer assumes that you don't actually care if the script file is in a plugin, theme, or child theme but instead want to find out the proper URL of some assets that you package with the script that will either be in the same directory or a sub directory.

function proper_url($directory) {
    $current_directory = forward_slashes($directory);
    $plugins_directory = forward_slashes(WP_PLUGIN_DIR);
    $themes_directory = forward_slashes(get_theme_root());

    if ( strpos( $current_directory, $plugins_directory ) !== FALSE ) {
        // Script is in a plugin
        $dir = str_replace( $plugins_directory, '', $current_directory);
        $url = plugins_url() . $dir;

    } elseif ( strpos ( $current_directory, $themes_directory ) !== FALSE ) {
        // Script is in a theme
        $dir = str_replace( $themes_directory, '', $current_directory);
        $url = get_theme_root_uri() . $dir;

    } else {
        // If needed, do error handling here
        $url = FALSE;
    }

    return $url;
}

/**
 * Handle Windows paths
 */
function forward_slashes($string) {
    return str_replace('\\', '/', $string);
}

Using proper_url(__DIR__) will return the URL of wherever the script that calls the function is. As an example, if using the function from:

/wp-content/themes/my-awesome-theme/my-framework/framework.php

will return:

http://www.example.com/wp-content/themes/my-awesome-theme/my-framework/

You will notice I'm using the constant WP_PLUGIN_DIR rather than plugin_dir_path() as the latter is just a wrapper for trailingslashit( dirname( $file ) ).

Answer 3

See php function http://php.net/manual/en/function.debug-backtrace.php

Source: Caller function in PHP 5?

I hope it helps you!