Design patterns

Milan Hradil, Nirdosh

14.08.2015

Wish list

loose coupling

code reuse (is not the same as copy/paste)

open for extension and closed for modification

encapsulate what varies

single responsibility principle

program against an interface not against an implementation (DI)

prefer composition over inheritance

(in fact this is all the same with different words)

Avoid tight coupling!

Otherwise you get into trouble

Pattern groups

Creational

Structural

Behavioral

Template Method

Behavioral type

Define the skeleton of an algorithm in an operation, deferring some steps to subclasses.

Lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.

Template Method

Template Method

abstract class Worker {
    public function DailyRoutine() {
        $this->getUp();
        $this->eatBreakfast();
        $this->goToWork();
        $this->work();
        $this->returnToHome();
        $this->relax();
        $this->sleep();
    }

    public function getUp() {}
    public function eatBreakfast() {}
    public function goToWork() {}
    abstract public function work();
    public function returnToHome() {}
    public function relax() {}
    public function sleep() {}
}

class FireFighter extends Worker {
    public function work() {
        echo "Fire fighting";
    }
}

class Manager extends Worker {
    public function work() {
        echo "People managing";
    }
}