I have 5 scripts, let’s say: database.php, parent.php, child1.php, child2.php and somescript.php
parent.php class looks like this:
include 'database.php';
class Parent {
public $db;
function __construct() {
$this->db = new Database();
}
}
child1 and child2 classes looks like this:
include 'parent.php';
class Child1 extends Parent {
function __construct() {
parent::__construct();
}
function useDb() {
$this->db->some_db_operation();
}
}
The problem
When I try to include both child1 and child2 in somescript.php, it returns the following error:
cannot declare class Database because the name is already in use in
database.php on line 4 (this is the line which contains words ‘class Database’)
But if I include only a single file (child1 or child2), it works great.
How do I correct that?
you want to use include_once() or require_once(). The other option would be to create an additional file with all your class includes in the correct order so they don’t need to call includes themselves:
“classes.php”
include 'database.php';
include 'parent.php';
include 'child1.php';
include 'child2.php';
Then you just need:
require_once('classes.php');
Answer：
try to use use include_onceor require_once instead of include or require
Answer：
Another option to include_once or require_once is to use class autoloading. http://php.net/manual/en/language.oop5.autoload.php
Answer：
You should use require_once and include_once. Inside parent.php use
include_once 'database.php';
And inside child1.php and child2.php use
include_once 'parent.php';
Answer：
I had this problem before and to fix this,
Just make sure :
- You did not create an instance of this class before
- If you call this from a class method, make sure the __destruct is set on the class you called from.
My problem (before) :
I had class : Core, Router, Permissions and Render
Core include’s the Router class, Router then calls Permissions class, then Router __destruct calls the Render class and the error “Cannot declare class because the name is already in use” appeared.
Solution :
I added __destruct on Permission class and the __destruct was empty and it’s fixed…
