PHP access class inside another class

Question

So I have two classes like this:

class foo {
    /* code here */
}
$foo = new foo();
class bar {
    global $foo;
    public function bar () {
        echo $foo->something();
    }
}

I want to access the methods of foo inside all methods bar, without declaring it in each method inside bar, like this:

class bar {
    public function bar () {
        global $foo;
        echo $foo->something();
    }
    public function barMethod () {
        global $foo;
        echo $foo->somethingElse();
    }
    /* etc */
}

I don't want to extend it, either. I tried using the var keyword, but it didn't seem to work. What do I do in order to access the other class "foo" inside all methods of bar?

user2453885 · Accepted Answer · 2014-05-04 18:49:23Z

9

You could do like this too:

class bar {
    private $foo = null;

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

    public function bar () {
        echo $this->foo->something();
    }
    public function barMethod () {
        echo $this->foo->somethingElse();
    }
    /* etc, etc. */
}

Later you could do:

$foo = new foo();
$bar = new bar($foo);

edited May 4, 2014 at 18:49

user2453885

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answered May 19, 2010 at 2:06

Sarfraz

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4 Comments

Waleed Khan Over a year ago

Never thought about passing it as a parameter; it works now. Thanks!

John Conde Over a year ago

FYI, that's known as Dependency Injection

zerkms Over a year ago

@John: it's too early to say someone about DI if he didn't even know about how to pass data through parameters.

klewis Over a year ago

This was super helpful in visually displaying how we can pass data from one class into another via parameters. Many thanks on the lesson!

Tesserex · Accepted Answer · 2010-05-19 02:05:33Z

3

Make it a member of bar. Try to never use globals.

class bar {
    private $foo;

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

    public function barMethod() {
        echo $this->foo->something();
    }
}

answered May 19, 2010 at 2:05

Tesserex

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Comments

zerkms · Accepted Answer · 2010-05-19 02:07:03Z

2

The short answer: nope, there is no way to implement what you want.

Another short answer: you're working with classes in "wrong" way. Once you selected Object Oriented paradigm - forget about "global" keyword.

The proper way of doing what you want is to create an instance of foo as member of bar and use it's methods. This is called delegation.

answered May 19, 2010 at 2:07

zerkms

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Comments

Scuzzy · Accepted Answer · 2015-02-03 04:09:23Z

1

And if your only focus is the methods themselves as opposed to the instance of another class, you can use x extends y.

class foo {
  function fooMethod(){
    echo 'i am foo';
  }
}

class bar extends foo {
  function barMethod(){
    echo 'i am bar';
  }
}

$instance = new bar;
$instance->fooMethod();

edited Feb 3, 2015 at 4:09

answered Feb 3, 2015 at 1:27

Scuzzy

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Comments

Omar Juvera · Accepted Answer · 2015-02-03 01:40:04Z

An option is to autoload your classes. Also, if you make your class a static class, you can call it without $classname = new classname():

//Autoloader
spl_autoload_register(function ($class) {
$classDir = '/_class/';
$classExt = '.php';
include $_SERVER['DOCUMENT_ROOT'] . $classDir . $class . $classExt;
});

//Your code
class bar {
    private static $foo = null; //to store the class instance

    public function __construct(){
        self::$foo = new foo(); //stores an instance of Foo into the class' property
    }

    public function bar () {
        echo self::$foo->something();
    }
}

If you convert your class (foo) into a static class

//Autoloader
spl_autoload_register(function ($class) {
$classDir = '/_class/';
$classExt = '.php';
include $_SERVER['DOCUMENT_ROOT'] . $classDir . $class . $classExt;
});

//Your code
    class bar {
        public function bar () {
            echo foo::something();
        }
    }

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