Undefined variable after using require_once

Question

I have created a Page class and all the pages on my website are objects of that Page class. Each Page object has a title attribute which is passed in as an argument to the constructor and so creating a new Page object looks as follows.

<?php

require_once('library/Page.php');

$page = new Page('About');

$page->header();

This is where the problem arises.

The header() method is...

public function header()
{ 

 require_once($this->templatePath . 'header.php');

}

I then echo the page title using

<?php echo $page->title; ?>

However, I get the following error.

Notice: Undefined variable: page in /Users/aaronfalloon/Projects/PHP/tfm/template/header.php on line 19

Notice: Trying to get property of non-object in /Users/aaronfalloon/Projects/PHP/tfm/template/header.php on line 19

Am I doing something wrong or do I need a work around to make it work?

Answer 1

I'm not sure, it may be possible to solve this issue by adding global $page; before the require_once call in your Page::header function.

The require_once includes the code of the specified file and execute it keeping the current scope. In your Page::header function, $page is not visible.

Answer 2

Use $this->title instead of $page->title since you refer to the property of the very same instance.

Answer 3

$page is declared as a global and the header.php code has only local scope to the method.

Either: Use global $page after the method declaration before the require_once.
Pass $page into the header function as an argument public function header($page).
Use echo $this->title in header.php.

Or if you really want to screw around use extract(get_object_vars($this)) and echo $title.

Answer 4

Let me further explain about what Gumbo has written.

When you included the template file, you did the operation WITHIN the header function, thus making all $page variable in the template file referring to the local $page variable in the header function, which apparently is not declared/defined.

You should use $this->title instead to refer to the current class.

It is something like

class Page{

  public function header(){
    echo $this->title;
  }

}

when you try to include the template file:

// page class
class Page{

  public function header(){
    include('template.php');
  }

}

.

// template file
echo $this->title;