Question

Why does PHP require you to explicitly write $this? I would understand if you had to use $this here:

function foo($bar) {
   $this->bar = $bar;
}

But you must write it explicitly in verbose code that looks like this:

$this->var3 = globalFun($this->var, $this->var2[$this->anotherVar], $this->method());

as opposed to:

$var3 = globaFun($var, $var2[$anotherVar], method());

So what is the point of $this?

Additional Bonus Question:

Why do we have to differentiate static references and instances? Why do we need:

static function getValue() {
   return self::value;
}

Can’t PHP find out at runtime if the variable/method in question is static? Now if I want to change a method from static to non-static, I have to replace all those self:: with $this-> (and vice-versa).

Wouldn’t it be better if we had a $this that behaves like it does in Java?

Answer 1

Okay, so let’s remove the need for writing $this everywhere. Take a look at this situation:

class Foo {
    public function setBar($value) {
        $bar = $value;
    }
}
$foo = new Foo();
$foo->setBar('some value');

Is $bar a local variable or a member of $foo?

There has to be some differentiation. They could have allowed declaration of local variables with the var keyword, but that would not have been backwards-compatible and would have been very confusing to people upgrading from older versions of PHP.

Same thing applies to self::. How does the interpreter know whether the function you wanted to call is global or specific to the class?