Question

For example lets say I have a set of classes and methods to do so:

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

Is there anyway for method1() to know with in itself that its the first method being called or for method2 to know that its the last?

Some more details
I just want to be able to build a set of these calls so that it either returns an instance of itself if the call to the method isnt at the end of the chain or return something different if its at the end.

For example

$obj->method1()->method2(); #Here method 2 will return lets say a string.
$obj->method1()->method2()->method3(); #Since method2 isnt at the end of the chain, it should return an instance of itself (or another object) here so that the chain could continue.

EDIT: anyone whoz trying to do this – it is a bad design pattern.

This does seem to be a duplicate. Refer to this question for more answers.

Answer 1

All you could do is find out which methods have been called so far, by setting some kind of global state in the class. But you can’t find out what methods are being called after a method, and you wouldn’t be able to tell the difference between methods in one chain and methods in another:

$obj->m1()->m2();
$obj->m3(); // You would think that m1() and m2() came before this in the same chain

You would need to have a method at the end of each chain to clear the global state in the class.

Since it seems you need to see which method comes next in a chain, this won’t work for you.

I would say that this is a really bad design pattern, at least for PHP (and every other language I’ve worked in). Each method should do one thing only. If you need a method to either return a string or an object depending on what you need it for later, you are doing something wrong.

Granted, I have done something like this before. It was a meta-information class for images submitted by users — you could set it up like this:

$meta = new ImageMeta();
$meta->first_name("foo")->last_name("bar")->email("baz")->id("guid");

But, if you did this:

$meta->first_name();

it would return a string. The default value for the first parameter was NULL, and if the method got NULL, it returned a string. Otherwise it set (and escaped) an internal value and returned $this.

At first I thought it was kind of cool, but it turned out to be a mistake. I hate using that class now. Just make one method/function do one thing only and you will be much happier.