Question

Introductory OOP question for you:

Situation: I want an abstract class with a public setter and abstract validator, since each child will validate that property in a unique way.

Code:

abstract class Parent {
    public function setName($name) {
        if (validateName($name)) {
            $this->_name = $name;
        } else {
            // error msg
        }
    }

    abstract public function validateName($name);
}

class Child extends Parent {
    public function validateName($name) {
        // ensure name gits this child's requirements
    }
}

Question: is this a “legal” design approach? I figured since the setName method will be the same for every child class, it should be a public method in the parent class, but the validator should be abstract to force child classes to implement it.

I’m just sketching this out on paper conceptually…

Answer 1

Yes, that’s a valid approach, although your syntax in imperfect:

        if (validateName($name)) {

should be this:

        if ($this->validateName($name)) {

But if this is the scope of the architecture, why not just define abstract setName() that validates and sets it? Like this:

interface Parent {
    public function setName($name);
}

class Child implements Parent {
    public function setName($name) {
        if (/* $name is valid */) {
            $this->_name = $name;
        } else {
            // error message
        }
    }
}

Of course I use an interface here, because there’s no code in Parent.

But please realize, this depends on how you’re program is structured. I’d have to see at least a diagram of the program’s architecture to say definitely either way.