OOPS - concepts in php

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OOPS -Concepts in PHP
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Topics to be covered

• Interfaces
• Abstract Classes
• Static Methods And Properties
• Accessor Methods
• Determining A Object's Class

• What is OOPS
• Class Objects
• Modifier
• Constructor
• Deconstructor
• Class Constants
• Inheritance In Php
• Magic Function
• Polymorphism

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What Is Oop ?

• Object Oriented Programming (OOP) is the
  programming method that involves the use of the
  data , structure and organize classes of an
  application. The data structure becomes an
  objects that includes both functions and data. A
  relationship between one object and other object
  is created by the programmer

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Classes

• A class is a programmer defined datatype which
  include local fuctions as well as local data.
• Like a pattern or a blueprint a oops class has
  exact specifications.  The specification is the
  class' s contract.

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Object
An object is a like a container that contains
methods and properties which are require to make
a certain data types useful. An objects methods
are what it can do and its properties are what it
knows.
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Modifier
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Modifier

• In object oriented programming, some Keywords
  are private and some are public in class. These
  keyword are known as modifier. These keywords
  help you to define how these variables and
  properties will be accessed by the user of this
  class.

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Modifier

• Private Properties or methods declared as
  private are not allowed to be called from outside
  the class. However any method inside the same
  class can access them without a problem. In our
  Emailer class we have all these properties
  declared as private, so if we execute the
  following code we will find an error.

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Modifier

• lt?
• include_once("class.emailer.php")
• emobject new Emailer("hasin_at_somewherein.net")
• emobject-gtsubject "Hello world"
• ?gt

The above code upon execution gives a fatal error
as shown below ltbgtFaprivate property
emailersubject in ltbgtC\OOP with
PHP5\Codes\ch1\class.emailer.phplt/bgt on line
ltbgt43lt/gtltbr /gt tal errorlt/bgt Cannot access That
means you can't access
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Modifier

• Public Any property or method which is not
  explicitly declared as private or protected is a
  public method. You can access a public method
  from inside or outside the class.
• Protected This is another modifier which has a
  special meaning in OOP. If any property or method
  is declared as protected, you can only access the
  method from its subclass. To see how a protected
  method or property actually works, we'll use the
  following example

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Modifier

• To start, let's open class.emailer.php file (the
  Emailer class) and change the declaration of the
  sender variable. Make it as follows
• protected sender
• Now create another file name class.extendedemailer
  .php with the following code

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Modifier

• lt?
• class ExtendedEmailer extends emailer
• function __construct()
• public function setSender(sender)
• this-gtsender sender
• ?gt

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Constructor Destructor

• Constructor is Acclimated to Initialize the
  Object.
• Arguments can be taken by constructor.
• A class name has same name as Constructor.
• Memory allocation is done by Constructor.

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Constructor Destructor

• The objects that are created in memory, are
  destroyed by the destructor.
• Arguments can be taken by the destructor.
• Overloading is possible in destructor.
• It has same name as class name with tiled
  operator.

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ClassContants
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Class Constants

• You can make constants in your PHP scripts
  utilizing the predefine keyword to define
  (constant name, constant value). At the same time
  to make constants in the class you need to
  utilize the const keyword. These constants really
  work like static variables, the main distinction
  is that they are read-only.

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Class Constants

• lt?
• class WordCounter
• const ASC1 //you need not use sign before
  Constants
• const DESC2
• private words
• function __construct(filename)
• file_content file_get_contents(filename)
• this-gtwords
• (array_count_values(str_word_count(strtolower
• (file_content),1)))

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Class Constants

• public function count(order)
• if (orderselfASC)
• asort(this-gtwords)
• else if(orderselfDESC)
• arsort(this-gtwords)
• foreach (this-gtwords as keygtval)
• echo key ." ". val."ltbr/gt"
• ?gt

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Inheritance
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Inheritance In Php

• Inheritance is a well-known programming rule, and
  PHP makes utilization of this standard in its
  object model. This standard will influence the
  way numerous objects and classes identify with
  each other.
• For illustration, when you extend a class, the
  subclass inherits each public and protected
  method from the guardian class. Unless a class
  overrides those techniques, they will hold their
  unique functionality

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Inheritance
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Magic Functions
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Magic Functions

• There are some predefine function names which
  you cant use in your programme unless you have
  magic functionality relate with them. These
  functions are known as Magic Functions. Magic
  functions have special names which begine with
  two underscores.

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Magic Functions

• _ _construct()
• _ _deconstruct()
• _ _call()
• _ _callStatic()
• _ _get()
• _ _set()
• _ _isset()
• _ _unset()

• __sleep()
• __wakeup()
• __tostring()
• __invoke()
• __ set_state()
• __ clone()
• __ debugInfo()

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Magic Functions

• _ _construct()
• Construct function is called when object is
  instantiated. Generally it is used in php 5 for
  creating constructor
• _ _deconstruct()
• It is the opposite of construct function. When
  object of a class is unset, this function is
  called.

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Magic Functions

• _ _call()
• When a class in a function is try to call an
  accessible or inaccessible function , this method
  is called.
• _ _callStatic()
• It is similar to __callStatic() with only one
  difference that is its triggered when you try to
  call an accessible or inaccessible function in
  static context.

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Magic Functions

• _ _get()
• This function is triggered when your object try
  call a variable of a class which is either
  unavailable or inaccessible.
• _ _set()
• This function is called when we try to change to
  value of a property which is unavailable or
  inaccessible.

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Polymorphism
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Polymorphism

• The ability of a object, variable or function to
  appear in many form is known as polymorphism. It
  allows a developer to programme in general rather
  than programme in specific. There are two types
  of polymorphism.
• compile time polymorphism
• run-time polymorphism".

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Interfaces
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Interfaces

• There are some specific set of variable and
  functions which can be called outside a class
  itself. These are known as interfaces. Interfaces
  are declared using interface keyword.
• lt?
• //interface.dbdriver.php
• interface DBDriver
• public function connect()
• public function execute(sql)
• ?gt

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Abstract Classes
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Abstract Classes

• A class which is declared using abstract keyword
  is known as abstract class. An abstract class is
  not implemented just declared only (followed by
  semicolon without braces)
• lt?
• //abstract.reportgenerator.php
• abstract class ReportGenerator
• public function generateReport(resultArray)
• //write code to process the multidimensional
  result array and
• //generate HTML Report
• ?

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Static Method And Properties
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Static Methods Properties

• In object oriented programming, static keyword is
  very crucial. Static properties and method acts
  as a significant element in design pattern and
  application design. To access any method or
  attribute in a class you must create an instance
  (i.e. using new keyword, like object new
  emailer()), otherwise you can't access them. But
  there is a difference for static methods and
  properties. You can access a static method or
  property directly without creating any instance
  of that class. A static member is like a global
  member for that class and all instances of that
  class

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Static Methods Properties

• lt?
• //class.dbmanager.php
• class DBManager
• public static function getMySQLDriver()
• //instantiate a new MySQL Driver object and
  return
• public static function getPostgreSQLDriver()

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Static Methods Properties

• //instantiate a new PostgreSQL Driver object and
  return
• public static function getSQLiteDriver()
• //instantiate a new MySQL Driver object and
  return
• ?gt

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Accessor Method
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Accessor Method

• Accessor methods are simply methods that are
  solely devoted to get and set the value of any
  class properties. It's a good practice to access
  class properties using accessor methods instead
  of directly setting or getting their value.
  Though accessor methods are the same as other
  methods, there are some conventions writing them.
  There are two types of accessor methods. One is
  called getter, whose purpose is returning value
  of any class property. The other is setter that
  sets a value into a class property.

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Accessor Method

• lt?
• class Student
• private name
• private roll
• More free ebooks http//fast-file.blogspot.com
• Chapter 2
• 39
• public function setName(name)
• this-gtname name

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Accessor Method

• public function setRoll(roll)
• this-gtroll roll
• public function getName()
• return this-gtname
• public function getRoll()
• return this-gtroll
• ?gt

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Determining A Object's Class

• public function setRoll(roll)
• this-gtroll roll
• public function getName()
• return this-gtname
• public function getRoll()
• return this-gtroll
• ?gt

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