Question

Can I write chainable functions in CodeIgniter?

So if I have functions like these :

function generate_error(){
    return $data['result']      =   array('code'=> '0',
                                      'message'=> 'error brother');
}

function display_error(){
      $a= '<pre>';
      $a.= print_r($data);
      $a.= '</pre>';
      return $a;
}

I want to call those by chaining them :

echo $this->generate_error()->display_error();

The reason why I want to seperate these functions are because display_error() is only useful for development, so when it comes to production, I can just remove the display_error() or something like that.

Thanks!

Answer 1

To write chainable functions they musy be part of a class, from the function you then return a reference to the current class (usually $this).
If you return anything other than a reference to a class it will fail.

It is also possible to return a reference to another class (e.g. when you use the code igniter active records class get() function it returns a reference to the DBresult class)

class example {

  private $first = 0;
  private $second = 0;

  public function first($first = null){
    $this->first = $first;
    return $this;
  }

  public function second($second = null){
    $this->second = $second;
    return $this;
  }

  public function add(){
    return $this->first + $this->second;
  }
}

$example = new example();

//echo's 15
echo $example->first(5)->second(10)->add();

//will FAIL
echo $example->first(5)->add()->second(10);