NYCPHP Meetup

[Alexander]

Thank you for detailed explanation...basically I was trying to do the
following:

Object of the base class($objBase) containing some data which I want to
copy to object of the derived class($objA). So I was looking for different
approches to this 'problem', and I was questioning myself if it is
possible to do that with type-casting, which you said is not supported in
PHP :) I guess it's good :)

code is somewhat like that

class Base
{
  var $a;
  var $b;
  var $c;
...
}

class A extends Base
{
  var $d;
  var $e;


function SomeKindOfTransormation(Base-type parameter)
{
//here I was trying to copy all data from argument
//as after it will be transormed and stored in the same variables

}

}


btw, as I'm using PHP4 is there any way to define function-member of the
class outside the class?

> What you've done above is make $objA a reference to $objBase - no
> "conversion".
>
> You might've meant you'd like to downcast it to a Base object.  TMK,
> downcasting is not supported at all in PHP.  It is commonly frowned upon
> in
> other languages because of problems that can arise.  In fact Java 1.5 even
> added features 5 which resemble, or are even identical to templates in C++
> (shudder<andrew> ... ;-) to avoid having to do it in the common cases like
> collections.  Anyway, I digress...
>
> If you were to do this in PHP it *might* resemble its counterparts in
> other languages:
>     $objAlikeBase = (Base) $objA;
> But like I said, you can't in PHP.  You may only cast between the
> primatives, not classes.
>
> If you really think you need to do this, give a better example of what
> your looking to do.
>
> Don't forget that an instance of class that extends another has the
> methods and properties of *both* classes or even interfaces.  It can
> also be used as both when code requires it like:
>
>     class shape { }
>     interface printable{ }
>     class circle extends shape implements printable { }
>
>     function draw(shape $o) { }
>     function myprint(printable $o) { }
>
>     $dot = new circle();
>
>     draw($dot);
>     myprint($dot);