Class with $_GET as variable doesn't work?

[DavidBonting]

Hello,
I can't figure out why this doesn't work. Because aren't both ways exactly the same?

<?php

    class checkBlog
    {
        var $id;
    
        function __construct()
        {
            $this->id=$_GET['b'];
        }

    
    }

$checkBlog = new checkBlog();
?>

<?php

    class checkBlog
    {
        var $id = $_GET['b'];
    
        function __construct()
        {

        }

    
    }

$checkBlog = new checkBlog();
?>

but with the second method:

Parse error: syntax error, unexpected T_VARIABLE in

Thanks in common,
David

[NogDog]

Class variables can only be initialized with literal values, not variables nor other expressions. It's a syntax error, but essentially it makes a certain sense, since when it's part of the class variable definition, you'd be trying to make the assignment at compile time (which is before $_GET actually gets populated), whereas when you assign it via the constructor it is assigned at run time, at which point $_GET has been populated. (An alternative would be to pass it as an argument to the constructor, so that it would be less closely coupled with the source of that value and theoretically more re-usable.)

[DavidBonting]

Oké thanks!