Learn PHP Classes

[Dysan]

Hi,

I am keen to learn how to code classes in PHP. Can anybody recommend any good websites/books?

[daredevil14]

hey... here's a quick start-up example...

<?php

class connection
  {
  function connect()
    {
    $sql = mysql_connect("xxx","xxx","xxx");
    }
  }

?>

above... we made a class called : connection, and it contains one method ( one function ) which is : the connection function... now the class itself is nothing... so how do we create objects ? ( an object is an instance of a class... )... here's an example on how to access the above connection function of our connection class :

<?php

// the above class is included...

$obj = new connection;
$obj -> connect();

?>

and bingo, a database connection was established... hope the above simple example will help you to continue on...

for more resources about classes, click here and here

Good luck...

[bpat1434]

I personally like the book by Matt Zandstra titled PHP Objects, Patterns and Practices. It's not a book to learn classes, but it will teach you the basics of classes and inform you of some patterns that arise that you might be able to use. It's a very good book.

Any PHP5 book should go over some basic class construction and use stuff. But I don't know of any real strictly classes php book.

[Dysan]

I think I understand. Can you give me an example, on how you would create a new class of dog, that inherits from a dog class?

[illzz]

The PHP Manual gives some information on this and some simple examples.

Classes and Objects (PHP 5) -- Extends

[bpat1434]

Here's a simple example:

class Animal
{
    protected $legs;
    protected $voice;
    protected $hair;

public function __construct() {}

public function hasLegs($legs=2)
{
    $this->legs = $legs;
}

public function setVoice($voice)
{
    $this->voice = $voice;
}


public function setHair($hair=body)
{
    $this->hair = $hair;
}

public function sayHello()
{
    echo $this->voice;
}
}

The above is our parent class. Now we can extend it like so:

class dog extends Animal
{
    public function __construct()
    {
        $this->setVoice('Woof Woof!');
        $this->setHair('All Over');
        $this->legs(4);
    }
}

So then you can do:

<?php

$dog = new dog();
$dog->sayHello();

If you pick up a book or two, they have plenty of examples on this.

[Dysan]

Should this:......

class Animal
{
    protected $legs;
    protected $voice;
    protected $hair;

public function __construct() {}

public function hasLegs($legs=2)
{
    $this->legs = $legs;
}

public function setVoice($voice)
{
    $this->voice = $voice;
}


public function setHair($hair=body)
{
    $this->hair = $hair;
}

public function sayHello()
{
    echo $this->voice;
}
}

...this:

class dog extends Animal
{
    public function __construct()
    {
        $this->setVoice('Woof Woof!');
        $this->setHair('All Over');
        $this->legs(4);
    }
}

.....and this:

<?php

$dog = new dog();
$dog->sayHello();

Be put in separate files?

Also, do you know of any good websites, where I can learn more?

[laserlight]

Do you know of any good websites, where I can learn more?

Someone recommended Object Mentor, and I believe I have come across some of their articles when searching for online OO references. Take a look at their published articles, in particular the sections concerning Design Patterns, Design Principles, and Object Oriented Design.

Of course, for syntax read the PHP manual, as recommended by illzz.

[NogDog]

If you are new to the world of object-oriented programming, I would recommend reading through Sun.com's Object-Oriented Programming Concepts tutorial. This gives a good background on the "why", then you can dive into the PHP manual and the various other PHP-specific references above to learn the "how".

[examancer]

bpat1434 wrote:

I personally like the book by Matt Zandstra titled PHP Objects, Patterns and Practices. It's not a book to learn classes, but it will teach you the basics of classes and inform you of some patterns that arise that you might be able to use. It's a very good book.

I second this recommendation. That is a great book and it taught me a ton about object oriented programming.

[Raptor2552]

Check this out PHP 101 from Zend http://devzone.zend.com/article/638-PHP-101-part-7-The-Bear-Necessities