PHP - use method chaining to extends previous method

Question

how can i do additional method(such as Laravel), that extends previous in chaining ? For example: $page->loadFooter()->withExtension("script_name") where withExtension() is additional method, that affect result of loadFooter() method ?

Answer 1

The way method chaining works is that each call has to return the object itself (i.e. $this).

So your page class definition would look like:

class Page {
    public function loadFooter() {
        /* ... */
        return $this;
    }

    public function withExtension($script) {
        /* ... */
        return $this;
    }
}

What's actually happening in method chaining is that the next function gets called on the returned object.

Answer 2

loadFooter() just needs to return an object that has a withExtension method. So if you want to affect the $page object than loadFooter should return its object.

/*Within $page's class*/

public function loadFooter(){
  /**insert Code**/
  return $this;
}

Answer 3

In your function you return an object, typically $this

class Page {
    public $footer;
    public function loadFooter() {
        $this->footer = file_get_contents("footer.html");
        return $this;
    }
    public function withExtension($script) {
        $this->footer = str_replace($this->footer, "</body>", "<script src='{$script}'></script></body>");
    }
}

$page = new Page();
$page->loadFooter()->withExtension("script name");