Accessing a Global Variable in a Method

Question

I think my question is kind of noobish but i can't figure out how this stuff is working with PHP. It is a autoloaded class and I want to use my logging class for it. I know I could have $log also as instance variable but I want it like that.

namespace Bal\Blub;

$log = new Logger('activities');
$log->pushHandler(new StreamHandler(__DIR__.'/../../log/activties.log', Logger::DEBUG));


$log->debug("is working here");

class Foo {
    public function bar() {
       global $log;
       $log->debug("this is my message");
    }
}

I don't understand why $log has no value in that case...

Edit: Of course I meant global and not public.

Where is $log global ? I just see a public class property, never assigned. How does Foo knows $log is an instace of the Logger class? — Damien Pirsy
– Damien Pirsy, Commented Jun 8, 2014 at 10:48

uphill · Accepted Answer · 2014-06-09 22:28:26Z

1

Ok so thanks for your code-style advises. I am quite aware that globals are bad practice. Though it was not my question. The answer for it is to use the global also in the namespace scope, which makes sense, but is a little strange if you are used to the PHP scripting approach.

namespace Bal\Blub;

global $log;

$log = new Logger('activities');
$log->pushHandler(new StreamHandler(__DIR__.'/../../log/activties.log', Logger::DEBUG));


$log->debug("is working here");

class Foo {
    public function bar() {
       global $log;
       $log->debug("this is my message");
    }
}

answered Jun 9, 2014 at 22:28

uphill

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Comments

Benjamin Eckstein · Accepted Answer · 2014-06-08 10:55:33Z

0

it is global $log. not public $log.

but be careful. globals are always evil. if you really need globals, use at least static variables.

<?php 
class Globalholder{
   public static $log;

}
Globalholder::$log = new Logger(...);


function foo(){
   $log = Globalholder::$log;
   $log->logsomething("Hello World");
}

answered Jun 8, 2014 at 10:55

Benjamin Eckstein

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Comments

Damien Pirsy · Accepted Answer · 2014-06-08 11:33:52Z

0

global keyword, a static class property acting like a global variable, a singleton class...all can work, but since we're at it, why not trying to avoid bad practices and use DI?

Right now, your Foo class is tightly coupled with the Logger class, and that can make maintaince hard whenever, some day, you're going to change all the reference to the Logger class.

Why not something simpler like:

class Foo

   protected $logger;

   public function __construct(Logger $logger)
   {
      $this->logger = $logger;
   }

   public function bar($string)
   {
       $this->logger->debug($string);
   }
}

$log = new Logger('activities');
$foo = new Foo($log);
$foo->bar("test");

This way you're decoupling (I know this code can be made even better) the two classes, and you're also making the code easy testable by passing a mock Logger object.

edited Jun 8, 2014 at 11:33

answered Jun 8, 2014 at 11:28

Damien Pirsy

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4 Comments

uphill Over a year ago

Totally agree, but why is my sample here not working? Why can't i access the variable here?

uphill Over a year ago

Then the answer to my question is that you need a global $log; also in the top of the file?

Damien Pirsy Over a year ago

It should be right like this, but again, why stick with global?

uphill Over a year ago

Thanks for suggesting me the class approach, I know it is better. ==> I know I could have $log also as instance variable but I want it like that. <== I wanted to know how it works the other way and how the PHP scope system works in that case.

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