Constructor: Guardian angel of a Class

Keywords

• constructor
• destructor

The role of the  constructor  is to check on the class once it is instantiated. The function __constructor will run as soon as the instance is created. If you don't create a constructor  function, there will be default constructor created.

Once object is created, it should be destroyed. The fourth generation programming languages destroy unused object, often referred as "Garbage Collection". You can enforce this

<?
class test {
function testfunc($value) {
echo "<font color='red'>testfunc Calling function construct </font><br>" ;
$this->__construct();
register_shutdown_function(array($this,"__destruct"));
echo " Class testfunc runtime $value <br>";
}
function __construct() {
echo "Constructor Evoked <br>";
}
function __destruct() {
echo "responding function destruct<br>";
echo "Free Memory <br>";
}
};
echo "<font color='red'><b>Load program :</b></font><br>";
$t=new test();
echo "Class Instance created <br>";
$t->testfunc(5);

?>
 

1. In the above example, you will notice that when you create an object with the keyword "new", the compiler looks for the constructor first .
2. Now after an object is created, when you are using the object, as shown below
   1.  t is the object,  a pointer "->", and a function with a parameter 5 "testfunction(5)" .
   2. again the constructor was evoked.
3. Once object is done with his designated task, it is time to destroy the object. In the above example constructor was called twice, and destroyed twice.