Re: [PHP] Beginner Tutorials for using CLASSES in PHP4

On 10/10/07, Tony Marston <tony@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:


""Nathan Nobbe"" <quickshiftin@xxxxxxxxx> wrote in message
news:7dd2dc0b0710091950i62159761le400b3839677bebd@xxxxxxxxxxxxxxxxx
On 10/9/07, Robert Cummings <robert@xxxxxxxxxxxxx> wrote:

On Tue, 2007-10-09 at 21:37 -0400, Nathan Nobbe wrote:

does a lawn mower not have blades; and gas and a control panel; does
it
not
have
wheels? my object modeling of a lawn mower would certainly have
these
things;
and most likely i would mark components of the engine as private.
and what does a lawn mower cut anyway; grass; i thought that was it.
so
if
there
was no grass could there still be an algorithm to cut it?
i say grass is part of the grass-cutting algorithm.

Well it helps to refine the algorithm, but let's say we use fingers
instead as our measure... I'm sure we would find that we could cut
grass
also >:)


good point.
the lawn mower is still consistent of its own parts and they
comprise its implementation.

-nathan

Yes, but a lawnmower does not contain grass, it is used to cut grass.
Whole
grass goes in and cut grass comes out. The lawnmower does not have any
grass
in its construction, therefore grass is not part of the implementation.


yes, you are right about the grass not being part of the implementation; i
agree.
however; the mower as i pointed out has its own member variables that
comprise its
implementation; and earlier you suggested that member variables dont
constitute the
implementation of a class; which is wrong;

here is my example; note; no grass; but it has member variables which
comprise its implementation.

<?php
class Lawnmower {
const GAS_MIN = 0;
const GAS_MAX = 10;

private $engineOn = false;
private $gasLevel = 5;

public function turnOn() {
if($this->canRun()) {
$this->engineOn = true;
} else {
echo 'you need to add gas to run the mower!';
}
}

public function mowGrass() {
echo 'the grass [or pehaps fingers] are being cut...';
}

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.';
return false;
}
}

public function checkGasLevel() {
return $this->gasLevel;
}

private function canRun() {
$canRun = false;

if($this->gasLevel > self::GAS_MIN) {
$canRun = true;
}

return $canRun;
}
}
?>

-nathan