I am developing a WordPress plugin which requires certain rules to be added to the .htaccess file of the WordPress installation upon activation of the plugin.

Initially, before I switched my code to OOP (with classes and functions) the hooks and this functionality was working. But after I switched it, it doesn't work.

register_activation_hook( __FILE__, array( 'Optimizo', 'activation' ) );

The above code is how I am trying to call the function 'activation' from the class 'Optimizo' which resides in the same file as where I am writing the above activation hook. The 'activation' function has the necessary classes in it which should be called upon activation. Below is the content of the function.

protected function activation() {


I am just wondering if I wrote the code wrong of is it because that the function is having the protected access specifier or if I am doing something entirely wrong.

PS the function 'activate' resides in another class which is being extended to the 'Optimizo' class.

1 Answer 1


The function needs to be public, but it can also be static.

For example, from the Akismet plugin:

In the plugin file:

register_activation_hook( __FILE__, array( 'Akismet', 'plugin_activation' ) );

In the Akismet class file:

public static function plugin_activation() {
  • I tried changing the function to 'public' from 'protected', but now I am getting the following error when I try to activate my plugin. "Fatal error: Uncaught Error: Using $this when not in object context" Also the function now looks like: public function activation() { $this->activate(); } May 14, 2019 at 14:11
  • And the activate function is also public public function activate() { ... } May 14, 2019 at 14:12
  • @MinhazIrphan $this is not available inside the static method.
    – nmr
    May 14, 2019 at 14:44
  • 1
    your callable references a static method, not a dynamic on, you would need to swap Optimizo for a variable instance of your class. Otherwise it would have to be static, and you'd need to change all the methods that function calls to static versions too
    – Tom J Nowell
    May 14, 2019 at 15:22
  • 2
    Thank you very much for all the answers, as @TomJNowell said, I changed the activation hook from register_activation_hook( __FILE__, array( 'Optimizo', 'activation' ) ); to register_activation_hook( __FILE__, array( $optimizo, 'activation' ) ); And it seems to be working fine... May 14, 2019 at 16:31

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