Re: Beginner Tutorials for using CLASSES in PHP4

All your examples all falling on deaf ears. The fact of the matter is that encapsulation does NOT mean data hiding, therefore I do NOT have to make all my member variables private. The fact that you have used interfaces in that example proves nothing to me. It is possible to code a solution which does not use interfaces, so what are the benefits of the "with interfaces" solution over the"without interfaces" solution. If there are no benefits then I prefer to stick with the "without interfaces" solution. Just because you CAN use interfaces does not mean that you MUST use interfaces. I can build solutions without them, so I do not see any advantage in using them. -- Tony Marston http://www.tonymarston.net http://www.radicore.org ""Nathan Nobbe"" <quickshiftin@gmail.com> wrote in message news:7dd2dc0b0710100950r482cec4fi5632fd5adf345e0d@mail.gmail.com... > and here is the interface example youve (Tony) been asking for. > the reason an interface is the best option here is because human hands and > grass are not related, > but they can both be cut (i didnt start the fingers thing, but it works > for > the example so im using it). > > also, notice the benefit of composition. the same mower can be used > invoke > the cut method on > different Cuttables at runtime. > the reason this works is because Cuttable encapsulates a family of similar > algorithms. know what > that ones called; the strategy pattern; i must be a patterns zealot. > > also, regarding the, is grass part of the algorithm thing; i thought about > it more; i think this boils down to > definition vs. instantiation. take functions for example; they have > formal > and actual parameters. > > function someFunction($formalParameter) { > echo $formalParameter . PHP_EOL; > } > > $actualParameter = 'Hello World'; > > someFunction($actualParameter); > > $actualParameter is not part of the someFunction implementation, but > $formalParameter is. > > in the same way (in the following example) the Grass instances are not > part > of the Lawnmower implementation, > but the member variables and method signatures (of Lawnmower) do > constitute > its implementation. > > <?php > class Lawnmower { > const GAS_MIN = 0; > const GAS_MAX = 10; > const BLADE_HEIGHT_MIN = 1; > const BLADE_HEIGHT_MAX = 5; > > private $engineOn = false; > private $gasLevel = 5; > private $bladeHeight = 3; > > public function turnOn() { > if($this->canRun()) { > $this->engineOn = true; > } else { > echo 'you need to add gas to run the mower!' . PHP_EOL; > } > } > > public function mowGrass(Cuttable $theGrass) { > $theGrass->cut($this->bladeHeight); > } > > public function turnOf() { > $this->enginOn = false; > } > > public function addGas($amountOfGas) { > if(($amountOfGas + $this->gasLevel) > self::GAS_MAX) { > $this->amountOfGas += $amountOfGas; > } else { > echo 'you will overflow the tank w/ all that gas.' . PHP_EOL; > return false; > } > } > > public function decreaseBladeHeight() { > if($this->bladeHeight > self::BLADE_MIN_HEIGHT) { > $this->bladeHeight--; > } else { > echo 'the blades are already at their lowest setting' . > PHP_EOL; > } > } > > public function increaseBladeHeight() { > if($this->bladeHeight > self::BLADE_HEIGHT_MAX) { > $this->bladeHeight++; > } else { > echo 'the blades are already at their highest setting' . > PHP_EOL; > } > } > > public function checkGas() { > return $this->gasLevel; > } > > private function canRun() { > $canRun = false; > > if($this->gasLevel > self::GAS_MIN) { > $canRun = true; > } > > return $canRun; > } > } > > interface Cuttable { > function cut($newHeight); > } > > class Grass implements Cuttable { > const MIN_HEIGHT = 0; > > private $grassHeight = 3; > > public function grow() { > $this->grassHeight++; > } > > public function cut($newHeight) { > if($newHeight < self::MIN_HEIGHT) { > echo 'dirt flying in every direction!' . PHP_EOL; > $this->grassHeight = self::MIN_HEIGHT; > } else { > $this->grassHeight = $newHeight; > } > } > } > > class HumanHand implements Cuttable { > private $numFingers = 5; > > public function cut($newHeight) { > //// TODO: ROB CAN FILL IN THE PART ABOUT WHAT HAPPENS TO THE > FINGERS :) > echo 'oh dear, i have to go to the hospital!' . PHP_EOL; > } > } > > > $myLawn = new Grass(); > $neighborsLawn = new Grass(); > $myMower = new Lawnmower(); > $myHand = new HumanHand(); > > // neighbors havent cut their grass in weeks > $neighborsLawn->grow(); > $neighborsLawn->grow(); > > echo 'ill cut my grass first at the standard blade height' . PHP_EOL; > $myMower->turnOn(); > $myMower->mowGrass($myLawn); > > echo 'now ill adjust the blade height, because the neighbors like their > grass tall' . PHP_EOL; > $myMower->increaseBladeHeight(); > $myMower->mowGrass($neighborsLawn); > > echo 'bummer; there is some gunk on the underside of the mower; pehaps ill > use my hand to dig it out..' . PHP_EOL; > $myMower->mowGrass($myHand); > ?> > > -nathan >