\Signal

An event(signal) system for CI.

The term event and signal are used to mean the same thing in this class.

This class listens for signals that occur within an application and notifies some other part of the system that a the signal has occurred.

Example

This maybe useful e.g. if you want to send email each time a new user is registered.

Loading The Library

To start using the signal dispatcher, load it like any other CODIGNTER library, preferably using autoload

$autoload['libraries'] = array(
         'powerdispatch/signal',<------------------------------------ the dispatcher
         'powerorm/orm',
         'powerauth/auth'
);

The Sender

For this to happen the user registration mechanism has to issue some signals to notify other parts of the system/application it has registered a user,

So in this case the user registration mechanism is called the sender. i.e it sends signals

To send a signal you use the \Signal::dispatch() method of the Signal class as shown in the example below

class User_model extends Base_model{
             ... // other methods

     public function save($args){
             ... // saving logic

         $saved_user = ...

         // notify everyone that is listening that a user has been registered
         $this->signal->dispatch('powerorm.model.post_save', get_class($this), $saved_user);
     }

}

class User_controller extends CI_Controller{
         ... // logic to save user
         $this->user_model->save($args);

}

Signal

A signal just a PHP string, When coming up with a signal name try to make them a unique as possible to avoid collisions with other parts of the application dispatching a signal having the same string for a signal.

e,g the one i have used 'powerorm.model.post_save' in the example. in which my models leave in a package called powerorm

The Receiver

Once the user registration mechanism has issued a notification that it has registered a user, The 'Signal' class, will notify all other parts of the application/system of this notification.

For any part of the system/application to be notified of this signals, it has to register with the Signal class.

Once registered it becomes a receiver i.e. it receives signals.

A receiver can be any PHP function or method that is it returns true when tested by is_callable() and callable via call_user_func()

Registering Receivers

To register recievers, create a file config/signals.php add create and array of receivers.

Just like you would CI HOOKS

Take Note of

$receivers['model.post_save'][] = ...

This allows for multiple receivers to listen for the same signal. The order you define your array will be the execution order.

Continuing with our example the first two receivers will be notified when the registration mechanism registers a user. Which will the perform some actions

// class method

$receivers['powerorm.model.post_save'][] = array(
     'class'    => 'Authauth', // the class to be invoked, leave blank if you just using a function
     'function' => 'auth_check', // function / method to be called
     'filename' => 'Authauth.php', // the file name containing the function or class with the method to be called
     'filepath' => 'libraries' // the directory where the file is located relative to the application directory.
);

// function

$receivers['powerorm.model.post_save'][] = array(
     'class'    => '',
     'function' => 'email',
     'filename' => 'sender.php',
     'filepath' => 'libraries'
     'sender' => 'user_model' // in this case we only want to listen for when user_model issues a `model.post_save` signal
);

// closure function

$receivers['powerorm.model.pre_save'][] =function($sender, $params){

};

// closure function
// not here that only one  receiver is listening for this signal
$receivers['powerauth.auth.login_success'] =function($sender, $params){

};

How it works

When a sender issues a signal, all the registered receivers are notified, the receivers the performs some action

Important Things To Note

Does not replace the CI Hooks but Works parallel to Hooks.
Load it early enough to be able to catch all signals. I recommend use ci autoload and make the first in the libraries array.

$autoload['libraries'] = array(
     'powerdispatch/signal',
     'session',
     'powerorm/orm',
     'powerauth/auth'
);

Similarity from CI HOOKS

Receivers are registered in a config file called config/signals.php
Registering a receiver requires same amount paramaters as hooks

Difference from CI HOOKS

A receiver can register to listen for specific senders only. see receiver example above
The receiver method get two mandatory arguments
- sender -- this is the object that sent the signal
- params -- This are extra arguments sent to the receiver by the sendender, while most sender will not send extra arguments the receiver is expected accept this argument this because the sender might start sending arguments in future

Summary

Methods

Properties

Constants

dispatch()

No public properties found

No constants found

No protected methods found

No protected properties found

N/A

No private methods found

No private properties found