PHP - How can I define "static" variables in a class

Question

I'm trying to call some "global/static" variables($agent, $version) inside a class but I don't know how to insert them in the class itself . Basically I declare the class "$myclass = new myClass($agent, $version) but I don't know how to call these variables inside the class (e.g. use them in the getProducts function ). I know the questions sounds stupid but I just don't get it .

index.php :

$myclass = new myClass($agent, $version);

$agent = "firefox";
$version = "234";

$catalog = $myClass->$getProducts("http://amazon.com", "red");

myclass.class.php :

class myClass {
    function getXML ($agent, $version) {
        //do something 
        return $
    }

    function getProducts ($url, $color) {
        $product = $this->getXML($agent, $version);
        $catalog =  str_replace("asus", "", $product);
        return $catalog
    }

}

you should declare the class first class myClass. Then initialize $agent and $version. Only after that you can instantiate it new myClass($agent, $version). But you did the reverse! — Shiplu Mokaddim
– Shiplu Mokaddim, Commented Jan 19, 2013 at 19:02
Make a constructor for the class and declare/initialize the variables of the class: php.net/manual/en/language.oop5.decon.php — art2
– art2, Commented Jan 19, 2013 at 19:05

Matt Whipple · Accepted Answer · 2013-01-19 19:04:03Z

1

It doesn't sound like static variables are what you're looking for and are best avoided unless you know what you're doing (they're not really object oriented and not needed at all in PHP 5.3+). From the code that you've provided it looks like your expecting to pass the arguments into the object instantiation (new), so you should create a constructor for the class that accepts the arguments and assigns them to instance variables to be used in the method.

answered Jan 19, 2013 at 19:04

Matt Whipple

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4 Comments

user1963938 Over a year ago

sounds great but how ? Btw I just want to get the job done not really do any state of the art project.

art2 Over a year ago

Are you doing an application or school project? If latter, shouldn't you do it by yourself, and learn? ;) Though either way, you should't outsource your work.

user1963938 Over a year ago

I do some work for myself meaning that instead to do it manually I'm trying to automate some tasks (php curl , scarping etc ). I don't understand why is so complicated to pass the arguments into the class.

art2 Over a year ago

Read the answer of Niko, or just pass them directly like this: $instance = new myClass("Firefox", "1234"); I see no point of using static class variables in this case. Before this, you naturally declare/initialize the variables inside the class.

Georgios Bitzes · Accepted Answer · 2013-01-19 19:05:36Z

1

You can declare them using the static keyword.

From http://php.net/manual/en/language.oop5.static.php :

class Foo
{
    public static $my_static = 'foo';

    public function staticValue() {
        return self::$my_static;
    }
}

print Foo::$my_static . "\n";

answered Jan 19, 2013 at 19:05

Georgios Bitzes

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3 Comments

user1963938 Over a year ago

I don't need $my_static = 'foo'; . I need the variables that were declared on the new class (e.g. $myclass = new Foo($a, $b, $c). I need the $a, $b, $c inside the class itself. How can I do that ?

art2 Over a year ago

But you need them inside the class, if you are doing OOP. You need to initialize the variables always first!

user1963938 Over a year ago

ok so is it impossible to get a variable that is outside of the class ? I mean isn't possible to pass it to the class itself when I initiate it ?

Niko · Accepted Answer · 2013-01-19 19:04:13Z

0

I suppose that you do not mean "static" variables but "properties":

class myClass {
    // Declare the properties
    private $agent, $version;

    public function __construct($agent, $version) {
        // Copy the arguments to the class members
        $this->agent = $agent;
        $this->version = $version;
    }

    public function getProducts($url, $color) {
        $product = $this->getXML();
        // ...
    }

    private function getXML() {
        // Use the values stored in $this->agent etc.
        $agent = $this->agent;
        // ...
    }
}

Usage:

$agent = "firefox";
$version = "234";
$instance = new myClass($agent, $version);
$catalog = $instance->getProducts("http://amazon.com", "red");

answered Jan 19, 2013 at 19:04

Niko

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1 Comment

user1963938 Over a year ago

I don't know why I understand your answer but didn't understand the PHP doc which provided a similar example

art2 · Accepted Answer · 2013-01-19 19:11:32Z

0

This is also wrong:

function getProducts ($url, $color){
  $product = $this->getXML($agent, $version);
  $catalog =  str_replace("asus", "", $product);
  return $catalog
}

You cant pass $agent and $version variables in the getXML method unless you dont either, construct them first, or pass them in your getProducts method.

answered Jan 19, 2013 at 19:11

art2

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