Where and why do we use __toString() in PHP?

php oop tostring
Stann picture Stann · Mar 2, 2011 · Viewed 27.2k times · Source

I understand how it works but why would we practically use this?

<?php
    class cat {
        public function __toString() {
            return "This is a cat\n";
        }
    }

    $toby = new cat;
    print $toby;
?>

Isn't this the same as this:

<?php
    class cat {
        public function random_method() {
            echo "This is a cat\n";
        }
    }

    $toby = new cat;
    $toby->random_method();
?>

can't we just use any other public method to output any text? Why do we need magic method like this one?

Answer

Lightness Races in Orbit picture Lightness Races in Orbit · Mar 2, 2011

You don't "need" it. But defining it allows your object to be implicitly converted to string, which is convenient.

Having member functions that echo directly is considered poor form because it gives too much control of the output to the class itself. You want to return strings from member functions, and let the caller decide what to do with them: whether to store them in a variable, or echo them out, or whatever. Using the magic function means you don't need the explicit function call to do this.

Related questions

When to use self over $this?

In PHP 5, what is the difference between using self and $this? When is each appropriate?

Read More
What is the difference between public, private, and protected?

When and why should I use public, private, and protected functions and variables inside a class? What is the difference between them? Examples: // Public public $variable; public function doSomething() { // ... } // Private private $variable; private function doSomething() { // ... } // Protected protected $variable; protected function …

Read More
How do I get a PHP class constructor to call its parent's parent's constructor?

I need to have a class constructor in PHP call its parent's parent's (grandparent?) constructor without calling the parent constructor. // main class that everything inherits class Grandpa { public function __construct() { } } class Papa extends Grandpa { public function __construct() { // call Grandpa's constructor …

Read More