PHP: Include one class functions to another

Question

I have large class foo, that I want to split to two separate classes (and files);

My class foo uses contruct function and noumerous $this references.

I need a second class bar to be an extension for original foo class, so I could still use contruction with additional parameter if to include bar class;

$includeBar = true;
$foo = new foo($config, $includeBar);

I've tried putting it this way:

Class bar extends foo {

   public function barFunction(){
      //some function of bar
   }
}


Class foo {

   public function __construct($config, $includeBar = true) {
      if ($includeBar) {
         include_once 'bar.php';
      }
   }

}

But when I call:

$foo = new foo($config, true);
$foo->barFunction();

It fails, saying

PHP Fatal error: Uncaught Error: Call to undefined method foo::barFunction()

What am I doing wrong? pls help, got stuck

In which page are you calling $foo = new foo($config, true); ? show us the includes from it. — user7941334
– user7941334, Commented Jan 8, 2018 at 1:32
What is the use case for this? Why not instead of passing $includeBar conditionally instantiate an instance of bar rather than foo when needed? — smashed-potatoes
– smashed-potatoes, Commented Jan 8, 2018 at 1:32
@aendeerei thats the whole script. I just initialize foo class and expect functions from bar class to be available as well as functions from foo; — Denis Matafonov
– Denis Matafonov, Commented Jan 8, 2018 at 1:35
it is simply the other way round. foo should extend bar. And then, when instanciating the class, call the extending one (foo). Then there's no need for a param $includeBar — Jeff
– Jeff, Commented Jan 8, 2018 at 1:42
In general, if you include a file inside a function, the code found in the file is callable only inside the function, not outside of it. — user7941334
– user7941334, Commented Jan 8, 2018 at 1:51

Jeff · Accepted Answer · 2018-01-08 02:22:58Z

It should be the other way round.
Bar is your base class, that contains all the methods that every sub class also needs. Foo is the extention, the extras, so Foo extends Bar.

<?php 

// file bar.php
Class Bar {
    public function __construct($config) {
         $this->config = $config;
    }

    public function barFunction() {
        echo "I'm everybody ".$this->config['msg'];
    }
}

// file foo.php
require_once('bar.php');

Class Foo extends Bar {
    public function fooOnly() {
        echo "I'm foo ".$this->config['msg'];
    }   
}


// consuming file index.php
include('foo.php');
$config = array('msg'=>'and I need coffee');
$foo = new foo($config);
$foo->barFunction();  // we can call this, because foo extends bar

// this won't work:
$bar = new Bar($config);
$bar->fooOnly();

// but this:
$bar->barFunction();
$foo->fooOnly();

(all the includes/requires can be omitted when using a proper autoloader!)

Vũ Nhật Anh · Accepted Answer · 2018-01-08 02:56:08Z

0

If you want reuse class methods or separate class method implementation I think you can use trait and then you can use keyword use to require functions to your class.

For example:

<?php
class Base {
    public function sayHello() {
        echo 'Hello ';
    }
}

trait SayWorld {
    public function sayHello() {
        parent::sayHello();
        echo 'World!';
    }
}

class MyHelloWorld extends Base {
    use SayWorld;
}

$o = new MyHelloWorld();
$o->sayHello();
?>

The above example will output:

Hello World!

answered Jan 8, 2018 at 2:56

Vũ Nhật Anh

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