class question

[xaos_master]

Hello all. I am at the point in my PHP learning that I am trying to understand how classes work. I am building an online RPG game using PHP and I would like to put classes to work for me. I know there is probably a better or easier way to do what I'm trying to do without using a class, but I want to try to incorporate classes into my project that I can understand them thtough practical example.

I want to build an oop class for 'character'

when users log in, they have the option of creating a character to play in the game. Now I have 2 MySQL database tables that will relate to this, 'character', and 'race'

to use 1 single field from each for this example:

In table: 'character' I have a field named 'strength' (one of the character statistics)

In the table 'race' I have a field named 'str_mod' (strength modifier)

I want to create a class to facilitate the character creation process.

I have a question.

1. Can I pull external data (as in a database query) to use in the class constructor to initialize the strength stat? For example, I pull the 'str_mod' data from the 'race' table and put it into an array in the standard way so it becomes race[str_mod]. The equasion to initialize the strength stat is (10 + (race[str_mod])).

so I would like to have something like this:
(in php 4)

<?php

class char {

var strength;

function char() {
$this->strength = (10 + (race[str_mod]));
$sql = "INSERT INTO `Character` ( `strength`)
VALUES ('$this->strength');
$result = $db->sql_query($sql); 
}
}
?>

would that work (assuming external data)?

[NogDog]

If you want to really think of this in a o-o way, consider that a "race" is a more specific type of "character". Therefore, you could define a "character" class, and then create a separate class for each race that extends the character class. Or better yet, if using PHP5, create a "character" interface and then have each "race" class implement that interface. Since you said "assuming PHP4":

class Character
{
  var $str_mod = 0;

  function Character()
  {
  }

  function setStrength($str)
  {
    $str += $this->str_mod;
    // save $str in DB or whatever it is you want to do with it
  }
}

class Dwarf extends Character
{
  var $str_mod = +1;
}

class Elf extends Character
{
  var $str_mod = -1;
}

// create a dwarf:
$char = new Dwarf();
$char->setStrength(rand(1,6) + rand(1,6) + rand(1,6));

[xaos_master]

That is a good idea. It is making me think about this in a different way.

But that still doesn't answer my main question. I guess my problem is with variable scope and how it relates to classes. I'm not sure if the class parses before or after the instance is instanciated. If I load the script with data such as with a query or with $_POST('var'), can I assume this data when defining methods within the class.

As a simpler example

<?php
class noob {

var $sum;
function cube($x){
$this->sum = ($x * $x * $x);
}}

$x = 5;
$blah = new noob();
echo ('sum = ' . $blah->sum);
?>

would that work?

[NogDog]

You define $x outside the scope of the class, so you'll have to pass that value to the object either via the constructor or the method (whichever makes more sense to the overall functionality). This example allows you to pass it either way (as well as defining a default value):

class noob 
{
  var $sum = 0; // set default value to 0

  function noob($x = '')   // optional arg for constructor
  {
    if($x !== '')
    {
      $this->sum = $x;
    }
  }

  function setSum($x)
  {
    $this->sum = $x;
  }

  function cube()
  {
    return($this->sum * $this->sum * $this->sum);
  }
}

// use set method:
$x = 5;
$foo = new noob();
// use default value:
echo "$x cubed = " . $foo->cube();
// change value:
$foo->setSum($x);
echo "$x cubed = " . $foo->cube();

// set via constructor:
$bar = new noob($x);
echo "$x cubed = " . $bar->cube();

[NogDog]

PS: super-globals such as $POST, $GET, and $_SESSION are available from within your class, so you don't have to pass them in to your class via method arguments.

[xaos_master]

Thanks for this 🙂 You've been extrememly helpful.