Chaining in OOP

[smartic]

while i try to learn Zend framework i saw this code:

$this->addDecorator('FormElements')->addDecorator('HtmlTag', array('tag' => 'dl'))->addDecorator('Fieldset')->addDecorator('DtDdWrapper');

I'm new in OOP, i need an example to do something like that.

[Markus]

Can you clarify your question please?

[pbmods]

Heya, Smartic.

You're probably talking about chaining (which falls under a programming style known as Fluent Interface).

When you want to implement chaining, you simply need to make sure that each method call returns a reference to its parent instance by using the $this keyword:

class Foo
{
  public function bar(  )
  {
    return $this;
  }
 
  public function baz(  )
  {
    return $this;
  }
}
 
$Foo = new Foo();
$Foo->bar()->baz();
 

PHP does not allow you to chain off of the constructor, so you have to initialize (in this case) the Foo instance in a separate statement.

Note that $Foo->bar() returns a reference to $Foo, which allows you to chain the subsequent call to baz(). It would be equivalent to writing this:

$Foo = new Foo();
$Foo->bar();
$Foo->baz();
 

[smartic]

thank you pbmods