How to change a public function inside a class of a plugin?

Question

I want to change one of the public functions inside a class contained in a WordPress plugin.

I don't want to edit that function directly because I will lose the edit when I update the plugin.

This is what the class and function looks like in the plugin:

/**
 * Class TCM_Comment_Helper
 *
 * Helper with the comment CRUD
 */
class Thrive_Comments_Helper {

    /**
     * The single instance of the class.
     *
     * @var Thrive_Comments_Helper singleton instance.
     */
    protected static $_instance = null;

    /**
     * Comment Extra fields
     *
     * @var array fileds from comment object that we do not use
     */
    protected static $_extra_fields
        = array(
            'comment_date_gmt',
            'comment_author_IP',
            'comment_author_email',
        );

    /**
     * Thrive_Comments_Helper constructor.
     */
    public function __construct() {

    }

    /**
     * Main Thrive Comments Instance.
     * Ensures only one instance of Thrive Comments Helper is loaded or can be loaded.
     *
     * @return Thrive_Comments_Helper
     */
    public static function instance() {
        if ( empty( self::$_instance ) ) {
            self::$_instance = new self();
        }

        return self::$_instance;
    }

    /**
     * Get photo avatar url based on the email
     *
     * @param string $email for the avatar.
     * @param array  $args  extra arguments.
     *
     * @return string
     */
    public function tcm_get_avatar_url( $email, $args = array() ) {
        $default_picture = tcms()->tcm_get_setting_by_name( Thrive_Comments_Constants::TCM_DEFAULT_PICTURE_OPTION );

        $args['size']        = Thrive_Comments_Constants::AVATAR_SIZE;
        $args['default_pic'] = $default_picture;
        if ( isset( $args['comment_id'] ) ) {
            $args['author_avatar'] = get_comment_meta( $args['comment_id'], 'comment_author_picture', true );
        }

        if ( $this->tcm_validate_gravatar( $email ) ) {
            $picture = get_avatar_url( $email, $args );
        } else if ( isset( $args['author_avatar'] ) && '' !== $args['author_avatar'] ) {
            $picture = $args['author_avatar'];
        } else {
            $picture = ( empty( $default_picture ) ) ? tcm()->plugin_url( 'assets/images/' . Thrive_Comments_Constants::TCM_DEFAULT_PICTURE ) : $default_picture;
        }

        return apply_filters( 'get_avatar_url', $picture, $email, $args );
    }

    /**
     * Check if an email has gravatar and return if true
     *
     * @param string $email user email.
     *
     * @return bool|string
     */
    public function tcm_validate_gravatar( $email ) {
        // Craft a potential url and test its headers.
        $protocol    = is_ssl() ? 'https' : 'http';
        $hash        = md5( strtolower( trim( $email ) ) );
        $uri         = $protocol . '://www.gravatar.com/avatar/' . $hash . '?s=512&d=404';
        $response    = tve_dash_api_remote_get( $uri );
        $header_type = wp_remote_retrieve_header( $response, 'content-type' );
        if ( ! $header_type || strpos( $header_type, 'image' ) === false ) {
            $valid_avatar = false;
        } else {
            $valid_avatar = $uri;
        }

        return $valid_avatar;
    }
}

The function I want to change is tcm_validate_gravatar. Specifically I want to change the variable $uri = $protocol . '://www.gravatar.com/avatar/' . $hash . '?s=512&d=404'; into $uri = $protocol . '://www.gravatar.com/avatar/' . $hash . '?s=512&d=mp'; because d=404 is giving me 404 warnings in Query Monitor.

I have tried putting something like this inside the functions.php of my child theme:

function tcm_validate_gravatar( $email ) {
  //My changes to the function go here
}
add_action( 'init', 'tcm_validate_gravatar', 20 );

I have also tried extending the class and putting that inside the functions.php of my child theme:

class Extended_Thrive_Comments_Helper extends Thrive_Comments_Helper {

   function tcm_validate_gravatar( $email ) {
      //My changes to the function go here
      return $valid_avatar;
    }
  }
}
add_action( 'init', 'tcm_validate_gravatar', 20 );

I have tried many variations of the above examples. For the sake of brevity I won't list them all out here. None of them have worked. The original function is always called, not the new one inside my functions.php child theme.

What is the best way to make changes to the tcm_validate_gravatar function inside the Thrive_Comments_Helper class without directly editing the plugin file?

Answer 1

It's not possible to overwrite the class function without modifying the file (unless your hosting supports some form of "monkey patching" as its called) you could check if this function "tve_dash_api_remote_get" has a filter in it that allows you to manipulate the uri