OOP: Display warning and deactivate the plugin if PHP version is less than 5.4

Here’s my bare-bones template that I use when creating a plugin with OOP. Feel free to modify to your liking.

Template

if ( !defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

if ( !class_exists( 'MyPluginName' ) ) {

    class MyPluginName {

        public function __construct() { // Call your actions/filters here
            add_action( 'tag', array( $this, 'plgn_abbr_function' ), 10, 1 );
        }

        // Begin functions here
        public function plgn_abbr_function() {
            # Code here...
        }
    }
}

if ( class_exists( 'MyPluginName' ) ) { // Instantiate the plugin class
    global $plgn_abbr;
    $plgn_abbr = new MyPluginName();
}

A few things I immediately noticed from skimming through your attempts:

1. You’d want to call your add_actions under the __construct() and have your functions places outside of that but you’ll need to change the layout of it as well.

2. You need to update how your add_action layout

   add_action( 'admin_notices', 'show_notice', 100 );

   This structure will not work when utilizing a class, it should be:

   add_action( 'admin_notices', array( $this, 'show_notice' ), 100 );

3. You’d need to append public before all of your functions like so:

   public function your_code()

Solution

Here’s an update to your code utilizing the template that I gave you above, it’s been tested and works on my end:

if ( !defined( 'ABSPATH' ) ) exit; // Exit if accessed directly

if ( !class_exists( 'MyPluginName' ) ) {

    class MyPluginName {

        public function __construct() {
            // check for required php version and deactivate the plugin if php version is less.
             if ( version_compare( PHP_VERSION, '5.4', '<' ) ) {
                add_action( 'admin_notices', array( $this, 'show_notice' ), 100 );
                add_action( 'admin_init', array( $this, 'MyPluginName_deactivate_self' ) );
                return;
            }
        }

        public function show_notice() {
            ?>
            <div class="error">
                <p><?php echo 'MyPluginName requires minimum PHP 5.4 to function properly. Please upgrade PHP version. The Plugin has been auto-deactivated.. You have PHP version '.PHP_VERSION; ?></p>
            </div>
            <?php
            if ( isset( $_GET['activate'] ) ) {
                unset( $_GET['activate'] );
            }
        }
        public function MyPluginName_deactivate_self() {
            deactivate_plugins( plugin_basename( __FILE__ ) );
        }
    }
}

if ( class_exists( 'MyPluginName' ) ) { // Instantiate the plugin class
    global $plgn_abbr;
    $plgn_abbr = new MyPluginName();
}