Cannot concatinate a variable to a protected variable?

[cancer10]

Hi

why does the following syntax generate an error:

<?php
class Foo
{
    protected $my_static = $var .  'foo';
}

Parse error: syntax error, unexpected T_VARIABLE in /var/www/test.php on line 4

[bacterozoid]

It's not because you can't concatenate stuff, it's because you can't use a variable there. When you instantiate that class, it has no idea what $var even is.

Something like this is probably what you want:

class Foo {

  protected $foo;

  function __construct($var) {
    $this -> foo = $var . 'bar';
  }

}

[cancer10]

That solved my problem.

Many thanks sir.

[Fou-Lu]

This description is a little inaccurate, though on the right lines. It doesn't matter if the scope was to include another member, the problem is that a default value to a member property cannot be an expression at all. Only constant data is allowed, not even a private $var = 4 + 4; is allowed.
As pointed out, a simple constructor gets around this problem completely. You don't even need to accept anything:

PHP Code:

public function __construct()
{
    $this->foo = 4 + 4;
} 


This is why I recommend initializing all variables within the constructor instead of the member signature. Since I like to keep it consistent, I won't split the two up, but more often than not a member property is dynamic in nature.