Updating Legacy Code

What is a Class?

Basic class definitions begin with the keyword class, followed by a class name, followed by a pair of curly braces which enclose the definitions of the properties and methods belonging to the class.

The class name can be any valid label which is a not a PHP reserved word. A valid class name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. As a regular expression, it would be expressed thus: [a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*.

A class may contain its own constants, variables (called "properties"), and functions (called "methods").

<?php

$var = 'a default value';

function displayVar($var) {
    echo $var;
}

<?php

class SimpleClass
{
  // property declaration
  public $var = 'a default value';

  // method declaration
  public function displayVar() {
    echo $this->var;
  }
}

$this

Creating a "new" Instance

<?php

$instance = new SimpleClass();

$instance->displayVar(); // Outputs 'a default variable'

Extending

<?php

class ExtendClass extends SimpleClass
{
    // Redefine the parent method
    public function displayVar()
    {
        echo "Extending class\n";
        parent::displayVar();
    }
}

<?php

class SimpleClass
{
  // property declaration
  public $var = 'a default value';

  // method declaration
  public function displayVar() {
    echo $this->var;
  }
}

$extended = new ExtendClass();
$extended->displayVar();

Output?

Visibility

<?php

class MyClass
{
    public $public = 'Public';
    protected $protected = 'Protected';
    private $private = 'Private';

    public function printHello()
    {
        echo $this->public;
        echo $this->protected;
        echo $this->private;
    }
}

$obj = new MyClass();

echo $obj->public; // Works
echo $obj->protected;// Fatal Error
echo $obj->private; // Fatal Error

What about $obj->printHello()?

How about extended printHello()?

The Indecisive Beer Drinker

if ( ! function_exists('random_beer'))
{
  function random_beer()
  {
    $beers = array(
      'Guiness',
      'Sam Adams',
      'Bells'
    );

    $key = array_rand($beers, 1);
    return $beers[$key];
  }
}

BeerHelper.php to the Rescue!

if ( ! function_exists('random_beer'))
{
  function random_beer()
  {
    $beers = array(
      'Guiness',
      'Sam Adams',
      'Bells'
    );

    $key = array_rand($beers, 1);
    return $beers[$key];
  }
}

<?php

class BeerHelper
{
  public static function random()
  {
    $beers = array(
      'Guiness',
      'Sam Adams',
      'Bells'
    );

    $key = array_rand($beers, 1);
    return $beers[$key];
  }
}

include "BeerHelper.php";

$giveMeA = BeerHelper::random();

Format

class Format
{
  public static function phone($num)
  {
    $clean = preg_replace("/\D/", "", $num);

    $area = substr($clean, 0, 3);
    $city = substr($clean, 3, 3);
    $local = substr($clean, 6, 4);

    return "(".$area.") ".$city."-".$local;
  }

  public static function date($date, $format = "F jS, Y")
  {
    $date = \DateTime::createFromFormat("Y-m-d", $date);
    return $date->format($format);
  }
}

Format::phone(1234567890);             // "(123) 456-7890"
Format::phone("123asdf456ggasdf7890"); // "(123) 456-7890"

Format::date('2012-08-21');            // "August 21st, 2012"

Databases: The Functional Way

$con = mysql_connect("localhost", "root", "") or die('Could not connect: ' . mysql_error());
mysql_select_db("accordion", $con) or die('Could not open database: ' . mysql_error());

$result = mysql_query("SELECT id, text, URL FROM topics ORDER BY ordering") or die('Error: ' . mysql_error());

while ($row = mysql_fetch_assoc($result)):
// Display the results to the screen
endwhile;

mysql_close($con);

You copy this into every page?

Let's Code A Database Class

My Class

class Database_MySQL
{
  protected $connection = null;

  public function __construct(array $config)
  {
    $this->connection = mysql_connect($config['host'], $config['user'], $config['password']) or die('error...');
    mysql_select_db($config['database', $this->connection]) or die('error....');
  }

  public function query($sql)
  {
    $result = mysql_query($sql); // Make sure your queries are safe!!!!!!!!!

    $resultSet = array();
    while($row = mysql_fetch_assoc($result))
    {
      $resultSet[] = $row;
    }

    return $resultSet;
  }

  public function __destruct()
  {
    if ($this->connection !== null)
    {
      mysql_close($this->connection);
    }
  }
}

On Your Own

• Constructors and Destructors
• Magic Methods
• Autoloading
• Abstraction
• Interfaces
• Exceptions
• Namespaces (5.3+)
• Traits (5.4+)

Resources

• PHP.net
• PHP FIG
• PHP the Right Way

array_map

Applies the callback to the elements of the given arrays

array array_map ( callable $callback , array $arr1 [, array $... ] )

$beers = array('guiness', 'sam adams', 'bells');
$capitalized = array_map('ucwords', $beers);

array(3) {
  [0]=> string(7) "Guiness"
  [1]=> string(9) "Sam Adams"
  [2]=> string(5) "Bells"
}

Questions? Comments?
@davewidmer