How to Elegantly Handle Inheritance

Kato

I have several class objects, such as a date object, a database object, and several "helpers" that perform specific routines for a data set. They extend eachother's functionality in a very special way.

The problem: PHP Only supports single inheritance. Thus I can only specify that each one extends another. Thus if one script needs C, B, and A's functions, then class C must extend B which extends A.

Then, if I have a page that just needs the formatting functions in class B, B must still extend A for the other pages to work with the C class who must extend both B and A to function.

Thus wasting valuable time and resources.

Ideas?

rrijnders

You should examine your object constructs carefully. Many times an object can utilize another object without having to extend it. For example, an "order" object may have one or more "date" objects as attributes, but there is no reason for "order" to extend "date". As long as both objects are defined to the script, "order" can simply instantiate instances of "date" using the new() operator and assign them to it's attributes ($shipdate, $orderdate, etc).

Just my $0.02USD

tomhath

Instead of using multiple inheritance and all the problems it brings, try using what's called a Decorator or Wrapper. I think it's a better solution:

http://www.csharp.org/whitepapers/dsgn_patterns/articles_20020111.pdf

tomhath

By the way, what rrijnders describes is a decorator class, the same thing I suggested.

Kato

Thanks for your suggestions.

I suppose I was hoping for a way to get the functions drawn into the current class with the same ease as the "extend" function.

However, I suppose it won't hurt to just call them from a Decorator, which, if I understand right, would be the following(?):

class NeedsDateFunctions {

var $date_functions;

function initialize_date_methods( ) {
$this->date_functions = new Date();
}

function another_method() {
// some code....
$this->date_functions->function();
}

}