register_activation_hook vs add_action（'init'）

Question

I'm trying to determine why some WordPress plugins use register_activation_hook(__FILE__, 'activate_plugin') while others use the action add_action('init', 'activate_plugin');

Answer 1

A few reasons:

• register_activation_hook is WP2+, add_action was available to use before that
• register_activation_hook allows the developer to specify the file the function resides in (although this seems rarely used)
• for me, register_activation_hook is 'cleaner'

So I'd bet that plugins using add_action date from before version 2 or the developer isn't aware of register_activation_hook