MCIS/UA PHP Training 2003 Chapter 8 Object-Oriented Concepts - - - PowerPoint PPT Presentation

PHP Training 2003 Chapter 8 Object-Oriented Concepts - Part 2

MCIS/UA

Introduction

• OOP was introduced in Chapter 5.
• Learned how to use classes that were already

defined.

• Chapter 8 will focus on creating your own classes.
• As an example, we will develop an organization class.
• The example is for demonstration purposes and may

not be the best way to implement this class.

• This is pure PHP

.

• >

Introduction

• PHP 4 has functional, but limited OOP support
• PHP 5 is expected to expand OOP support

hands-on agenda

Hands-on Agenda

• Create an organization class/object to manage all the
• perations of an organization
• Functions
• get a list of all the organizations
• get information for an organization
• modify information for an organization

defining

Defining a class

• Classes are defined using the class keyword:

class classname { }

• Classnames follow the same rules as function names.

do

Defining a class

• rganization.php

<?php class organization { } ?>

• >

Defining a class

Application.php

<?php $cfg_appname = "My Application"; $cfg_sessionname = "covertka_myapp"; require_once "organization.php"; $presentation = new MU_Presentation(); [...] methods

Methods

• As discussed previously, functions in a class are called

methods.

• There are 2 types of methods:
• static or class methods
• called on the class itself
• not tied to a particular instance
• instance methods
• called on an instance of the class

do

Static Methods

• Static methods are called on the class itself.
• Static methods are declared within the class just like

any other function.

• Static methods are called using the :: operator

rather than the -> operator

classname::methodname(params...)

$orgs = organization::allOrgs(); do

Static Methods

• rganization.php

<?php class organization { function allOrgs() { $dbh = new dataSource("PHP_Training_Banner"); $query = "select shortname from orgs"; return $dbh->queryall_list($query); } } ?> methods

Static Methods

view.php <?php [...] $dbh = new dataSource("PHP_Training_Banner"); $query = "select * from orgs $order_by"; $data = $dbh->queryAll_array($query); $recordCount = count($data); $orgs = organization::allOrgs(); $recordCount = count($orgs); [...] ?> instance methods

Instance Methods

• Instance methods are called on an instance of a class.
• Instance methods are declared within the class just

like any other function.

• Instance methods are called using the -> operator

$org = new organization("chess"); $desc = $org->get("description");

• >

Instance Methods

• The pre-defined variable $this can be used in your

class to refer this particular instance.

$org1 = new organization("chess"); $org2 = new organization("musf"); $desc1 = $org1->get("description"); constructors

Constructor Methods

• Constructor methods are called when an instance is

created using the new keyword.

• Constructor methods have the same name as the

name of you class.

class organization { function organization() { [...] } } do

Constructor Methods

• rganization.php

<?php class organization { var $dbh; var $data; function organization($sn = "") { $this->dbh = new dataSource("PHP_Training_Banner"); if ($sn) { $query = "select shortname, description,". "to_char(startdate,'mm/dd/yyyy') as startdate,". "to_char(enddate,'mm/dd/yyyy') as enddate, advisor ". "from orgs where shortname=?"; $this->data = $this->dbh->queryFirstRow_assoc($query, $sn); } } function allOrgs() { $dbh = new dataSource("PHP_Training_Banner"); $query = "select shortname from orgs";

• >

Constructor Methods

view.php <?php [...] for($i = $start - 1; $i < $start + $show - 1 && $i < $recordCount; $i++) { $row = new Organization($orgs[$i]); $tabulator_row =& $table->add_element('tabulator_row'); $tabulator_row->add_element('tabulator_row_href', NULL, 'modify.php?shortname='.urlencode($orgs[$i])); [...] ?>

• >

Instance Methods

• rganization.php

<?php class organization { [...] function get($attribute) { return $this->data[$attribute]; } function getAllData() { return $this->data; } } ?>

• >

Instance Methods

view.php <?php [...] for($i = $start - 1; $i < $start + $show - 1 && $i < $recordCount; $i++) { $org = new Organization($orgs[$i]); $tabulator_row =& $table->add_element('tabulator_row'); $tabulator_row->add_element('tabulator_row_href', NULL, 'modify.php?shortname='.urlencode($orgs[$i])); foreach($org->getAllData() as $column => $value) { $tabulator_row->add_element('tabulator_row_data', array('name' => $column), htmlspecialchars($value)); } } [...] ?>

instance variables

Instance Variables

• Variables that hold information specific to this instance are

called instance variables.

• Instance variables should be declared at the beginning of the

class using the var keyword.

var variablename; var variablename = value; var $dbh;

• Instance variables are accessed similarly to instance methods

$instance->variablename;

$dbh->statement_tracking = true; do

Instance Variables

• rganization.php

<?php class organization { var $dbh; var $data; var $isValid = false; function organization($sn = "") { $this->dbh = new dataSource("PHP_Training_Banner"); if ($sn) { $query = "select shortname, description,". "to_char(startdate,'mm/dd/yyyy') as startdate,". "to_char(enddate,'mm/dd/yyyy') as enddate, advisor ". "from orgs where shortname=?"; $this->data = $this->dbh->queryFirstRow_assoc($query, $sn); if ($this->data) { $this->isValid = true; } } } function allOrgs() {

inheritance

Inheritance

• Classes in PHP can extend other classes.
• In doing so, they inherit all of the properties and methods of

the original class.

• The extend keyword is used to indicate the class you are

extending.

class facultyOrganization extends organization { var $department = ""; . . . } serialization

Serialization

• Serialization allows an application to convert an instance into a

string representation of the instance.

• The serialize() and unserialize() functions are used for this

purpose.

$org = new Organization($orgs[$i]); $sorg = serialize($org); print $sorg;

• utput

Serialization

• O:12:"organization":2:{s:3:"dbh";O:8:"dbh_oci8":16:{s:4:"u

ser";s:11:"PHPTRAINING";s:8:"database";s:4:"UAP5";s:4:"typ e";s:4:"oci8";s:9:"connected";b:1;s:2:"db";i:0;s:7:"driver s";N;s:5:"query";s:202:" select shortname, description, to_char(startdate,'mm/dd/yyyy') as startdate, to_char(enddate,'mm/dd/yyyy') as enddate, advisor from orgs where shortname='chess'";s:11:"auto_commit";b:1;s:18:"statement_ tracking";b:0;s:11:"_statements";a:0:{}s:5:"error";s:0:""; s:12:"error_string";N;s:9:"error_num";N;s:13:"trigger_erro r";b:1;s:19:"default_date_format";s:22:"DD-MON-YYYY HH24:MM:SS";s:6:"result";i:0;}s:4:"data";a:5:{s:9:"shortna me";s:5:"chess";s:11:"description";s:41:"Miami University Chess Club - Check Mates";s:9:"startdate";s:10:"06/27/ 2010";s:7:"enddate";s:10:"07/01/ 1988";s:7:"advisor";s:8:"covertka";}}

unserialize

Serialization

• Unserializing is performed using the unserialize()

function.

$org = unserialize($sorg); __sleep & __wakeup

Serialization

• The __sleep() method of a class, if present, is called

at the beginning of the serialization process in order for the class to perform any cleanup tasks.

• The __wakeup() method of a class, if present, is

called at the end of the unserialization process in

• rder for the class to perform any initialization tasks.

end

Questions?