Undefined function wp_set_password

Question

I'm creating a plugin. I'm receiving the following error (WP 3.5):

Fatal error: Call to undefined function wp_set_password() in \path\to\plugin.php on line 18

Line 18 consists of simply:

wp_set_password( 'newpass', $user_id );

This is located in the main plugin file, and all other code has been commented out in order to try and seclude this error. I have no idea why it's showing up as undefined.

Am I missing something here?: http://codex.wordpress.org/Function_Reference/wp_set_password

Thanks

Answer 1

When your plugin loads, pluggable functions aren't loaded yet, in fact a lot of stuff is not loaded yet, this what actions are for. Hook your function to an action, like plugins_loaded or init, when the WP environment is loaded and initialized:

add_action( 'init', 'wpa80246_init' );

function wpa80246_init(){
    wp_set_password( 'newpass', $user_id );
}