How to explain 'this' keyword in a best and simple way?

Question

I am using 'this' keyword for a long time. But when someone asks me to explain it, I am confused that how to explain it. I know that I can use this in a method of class to access any variable and method of the same class.

    class MyClass{

      function MyMethod1(){
        echo "Hello World";
      }

      function MyMethod2(){
        $this->MyMethod1();
      }

    }

Is it a object of a class that we don't need to initialise and can be used only within the class or anything else. How to explain?

Thanks

Solution 1

A class is a mold for an object: it specifies how the object looks like (variables) and what it can do (functions).

If you instanciate a class: you create an object. If you create the class, you can use "this" to refer to the object itsself. This is why you can't set the "this", because it's related to the object. It's a special, read-only variable.

Solution 2

this references the current object instance of a class.

this is an implicitly parameter passed to the methods of a class: it is scoped to a method and allows access to all of the object's members.

Solution 3

Like their name suggests, instance methods operate on instances of a class. How do they know which one to operate on? That's what the this parameter is for.

When you invoke an instance method, you're really invisibly passing in an extra parameter: the object to invoke it on. For example, when you have this:

class Basket {
  public function a() {
    $this-> ...;
    // ...
  }
  // ...
}

and you call $some_basket->a(), behind the scenes you're actually calling something like Basket::a($some_basket). Now a() knows which Basket you want to work with. That special parameter is what this refers to: the current object you're dealing with.

Solution 4

Several people have explained it in similar terms, but thought I'd add that when speaking to people unfamiliar with object oriented programming, I explain that the class definition is the blueprint, as for a house, and "this" is the actual house you're working with at that moment. There might be other houses that look exactly the same, but this is the specific object (house).

Solution 5

short: $this gives you access to the object variables (and methods) Edit: within the class :) Edit 2: (but not in static methods of the class) :D

View more solutions