CODEWITHSUNDEEP
phpoopinheritanceextends
Nimi
Nimi

Reputation: 599

Calling Parent Function with the Same Signature/Name

A and B have function with the same signature -- let's assume : foo($arg) -- and that class A extends B.

Now I have an instance:

$a = new A();

$a.foo($data);

Can I also run the parent's (B's) foo() function through $a or was it overridden?

Thanks! Nimi

Upvotes: 9

Views: 8997

Answers (6)

knittl
knittl

Reputation: 265341

. is the string concatenation operator in PHP. To call methods, use ->.

To call an overridden method, use parent::method()

class B {
  public function foo($data) {
    echo 'B';
  }
}

class A extends B{
  public function foo($data) {
    parent::foo($data);
    echo 'A';
  }
}

$a = new A();
$a->foo($data); // BA
$b = new B();
$b->foo($data); // B

Upvotes: 7

liquorvicar
liquorvicar

Reputation: 6106

In answer to your question, no, you can't call the parent's foo() method through an object of class A as the only foo() method the object A understands in its public API is its own foo() method. You probably need to think about your design. If B's foo() is providing different functionality to A's foo() then should one override the other? Or you need to think about A's foo() calling B's foo() via parent::foo() - assuming you want B's foo() called every time A's foo() is called. Or use another pattern. If A's foo() isn't always appropriate for an object of A then you might want to look at the Decorator or Strategy patttern's.

If you're starting out with OO programming I can't recommend the Gang of Four book highly enough.

Upvotes: 1

Berry Langerak
Berry Langerak

Reputation: 18859

Can I also run the parent's foo() function through $a or it was override ?

Not from the "outside". Say:

<?php
class A {
    function talk( ) {
        return 'Hello world';
    }
}
class B extends A {
    function talk( ) {
        return 'Goodbye world';
    }
}

$b = new B;
$b->talk( ); // Goodbye world.

In this example, it's not possible to have $b->talk output A::talk( ), other than proxying that through B. If you need to have the result from A instead of B, you might want to explain your dilemma; that's a problem you shouldn't run into, and if you do, the chances are the design isn't optimal.

Upvotes: 0

Dennis
Dennis

Reputation: 2142

In class A you can write 

parent::foo($param);

to call the base classes foo(...) method.

Upvotes: 0

ChrisR
ChrisR

Reputation: 14447

you can access the parents methods with parent::foo()

Upvotes: 0

Niels
Niels

Reputation: 49929

It is overridden but if you want to use both you can do this:

function parentFoo($arg)
{
    return parent::foo($arg);
}

If you want that the child function calls the parent function do this:

function foo($arg)
{
    $result = parent::foo($arg);
    // Do whatever you want
}

See this URL for more information: http://php.net/manual/en/keyword.parent.php

Upvotes: 15

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