Access variable defined in other file from class

Question

I would like to know if there is a way to access a variable defined in an other file from a class in PHP.

Example :

file_01.php

<?php
    $a = 42;
?>

file_02.php

<?php
    require_once('file_01.php');

    class mnyClass
    {
        private $myVar;

        function __construct($var = $a)
        {
            $this->myVar = $var;
        }

        function getVar()
        {
            return $this->var;
        }

        function setVar($var)
        {
            $this->myVar = $var;
        }
    }
?>

Obviously, my class is more complicated. I have chosen this example for a better comprehension of what I try to do ;)

Thank you in advance.

First of all, I thank you all for your answers. Indeed, I wanted to set up application defaults, but with association arrays. The define() method does not take an array as parameter. I knew the $GLOBALS variable but it can't be used in constructor parameters : / So, I resign to use $GLOBALS in my constructor with NULL tests on parameters. — Doc_1faux
– Doc_1faux, Commented Dec 6, 2011 at 16:09

Naftali · Accepted Answer · 2011-12-06 15:33:05Z

3

You cannot do this:

    function __construct($var = $a)
    {
        $this->myVar = $var;
    }

What you can do is pass it:

<?php
    require_once('file_01.php');
    $mnyClass = new mnyClass($a);// the torch has been passed!

    class mnyClass
    {
        private $myVar;

        function __construct($var = null)
        {
            $this->myVar = $var;
        }

        function getVar()
        {
            return $this->var;
        }

        function setVar($var)
        {
            $this->myVar = $var;
        }
    }
?>

OR you can do this (it is not advisable):

    function __construct($var = null)
    {
        if($var === null) $var = $GLOBALS['a']; //use global $a variable
        $this->myVar = $var;
    }

answered Dec 6, 2011 at 15:33

Naftali

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2 Comments

Frank Over a year ago

out of curiosity, why is it not advisable?

Naftali Over a year ago

@Frank you cannot scope global variables.

Steve · Accepted Answer · 2011-12-06 15:46:46Z

2

You could access the variable via GLOBALS:

http://php.net/manual/en/language.variables.scope.php

EDIT: a little more detail-

function __construct() {
  $this->myVar = $GLOBALS['a'];
}

edited Dec 6, 2011 at 15:46

answered Dec 6, 2011 at 15:35

Steve

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Comments

Alex Howansky · Accepted Answer · 2011-12-06 15:39:40Z

1

It sounds like you're setting up some application defaults. It might make sense to define these as constants:

file_01.php:

define('DEFAULT_VALUE_FOR_A', 42);

file_02.php

class myClass
{
    function __construct($var = DEFAULT_VALUE_FOR_A) {
    }
}

answered Dec 6, 2011 at 15:39

Alex Howansky

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Comments

Doc_1faux · Accepted Answer · 2011-12-07 07:02:44Z

0

Finally, I use this method :

<?php

require_once('file_01.php');

class myClass {

    private $myVar;

    function __construct($var = NULL)
    {
        global $a;

        if($var == NULL)
            $this->myVar = $a;
        else
            $this->myVar = $var; 
    }
}

?>

I declare my variable $a as global in the constructor, set the default value of my $var to NULL and check if the constructor was called with parameter(s) ($var == NULL).

answered Dec 7, 2011 at 7:02

Doc_1faux

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