Calling a Method on a method

Question

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PHP method chaining?

So I can remember seeing in some code examples somewhere calling of a method on a method like:

$classname->method1()->method2();

Can you please explain to me what we call this, and give an example scenario of its usage? Also if you have a link to a tutorial or article on this would be helpful.

I'm new to Object Oriented PHP. And before you kill me for what might be a dumb question, understand that i don't know what to search for on Google, please help...

method chaining.. tutorial here http://en.wikipedia.org/wiki/Method_chaining — Esailija, Jan 07 '12 at 22:58
Hey sorry tim, i didnt know what to search for, thats why i post a question — Joshua Kissoon, Jan 07 '12 at 23:00
Hey Joshua don't worry about it, it's hard to search for stuff when you don't know what it's called! Now the next guy that seraches for "Calling a Method on a method" will be eventually directed to the duplicate. — Wesley Murch, Jan 07 '12 at 23:01

score 2 · Answer 1 · answered Jan 07 '12 at 22:58

It's called Method chaining. Basically it's when a function or method, in this case method1(), returns an object and you call another method on this returned object.

A typical use of this is when a method returns the object itself. This can be useful because it makes calling lots of methods on the same object very simple. You can just type:

myobj.doSomething().doSomethingElse().jump();

One prominent example of this is the JavaScript library jQuery in which most methods return a jQuery object.

Hey Thanks you, already making use of this in my code. Though Using "->" and not ".", since its php — Joshua Kissoon, Jan 07 '12 at 23:16

score 2 · Accepted Answer · answered Jan 07 '12 at 22:59

It's called method chaining and it's simply the process of calling a method on the object returned by another method.

For example, method1 here returns an instance of some class that defined a method called method2, and so that method can be invoked immediately if you don't need the reference itself that method1 returned. It's essentially equivalent to this:

$temp = $object->method1();
$temp->method2();

It's particularly useful when you have several methods returning references to the instance they were called on. In this case, rather than writing this:

$object->method1();
$object->method2();
$object->method3();

you can write this:

$object->method1()->method2()->method3();

Hey Thanks a mil for the explanation, already making use of this in my code. — Joshua Kissoon, Jan 07 '12 at 23:14

Calling a Method on a method

2 Answers2