PHP Assigning a default Function to a class

Question

Im relatively new to PHP but have realized it is a powerfull tool. So excuse my ignorance here.

I want to create a set of objects with default functions.

So rather than calling a function in the class we can just output the class/object variable and it could execute the default function i.e toString() method.

The Question: Is there a way of defining a default function in a class ?

Example

class String {
     public function __construct() {  }

     //This I want to be the default function
     public function toString() {  }

}

Usage

$str = new String(...);
print($str); //executes toString()

Gordon · Accepted Answer · 2012-01-26 14:33:43Z

10

There is no such thing as a default function but there are magic methods for classes which can be triggered automatically in certain circumstances. In your case you are looking for __toString()

http://php.net/manual/en/language.oop5.magic.php

Example from Manual:

// Declare a simple class
class TestClass
{
    public $foo;

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

    public function __toString()
    {
        return $this->foo;
    }
}

$class = new TestClass('Hello');
echo $class;
?>

edited Jan 26, 2012 at 14:33

Gordon

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answered Jan 26, 2012 at 14:33

Rene Pot

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3 Comments

MetalFrog Over a year ago

Isn't this just used as a way to define how the class should be returned when requested as a string?

IEnumerable Over a year ago

I like this method, very clear and simple, cant believe google didnt find it. Thankyou so much..

MetalFrog Over a year ago

Gotcha, seems that I didn't interpret the question the right way. :D

Rene Pot · Accepted Answer · 2012-01-26 14:44:29Z

2

__toString() is called when you print your object, i.e. echo $str.

__call() is the default method for any class.

edited Jan 26, 2012 at 14:44

Rene Pot

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answered Jan 26, 2012 at 14:43

Al_

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Comments

MetalFrog · Accepted Answer · 2012-01-26 14:36:01Z

1

Either put the toString function code inside __construct, or point to toString.

class String {
     public function __construct( $str ) { return $this->toString( $str ); }

     //This I want to be the default function
     public function toString( $str ) { return (str)$str; }
}

print new String('test');

answered Jan 26, 2012 at 14:36

MetalFrog

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