void
__construct ( [mixed args [, ...]] )
PHP 5 allows developers to declare constructor methods for classes.
Classes which have a constructor method call this method on each
newly-created object, so it is suitable for any initialization that the
object may need before it is used.
Note:
Parent constructors are not called implicitly if the child class defines
a constructor. In order to run a parent constructor, a call to
parent::__construct() within the child constructor is
required.
Example 19-6. using new unified constructors |
<?php
class BaseClass {
function __construct() {
print "In BaseClass constructor\n";
}
}
class SubClass extends BaseClass {
function __construct() {
parent::__construct();
print "In SubClass constructor\n";
}
}
$obj = new BaseClass();
$obj = new SubClass();
?>
|
|
For backwards compatibility, if PHP 5 cannot find a
__construct() function for a given class, it will
search for the old-style constructor function, by the name of the class.
Effectively, it means that the only case that would have compatibility
issues is if the class had a method named
__construct() which was used for different semantics.
void
__destruct ( void )
PHP 5 introduces a destructor concept similar to that of other
object-oriented languages, such as C++. The destructor method will be
called as soon as all references to a particular object are removed or when
the object is explicitly destroyed.
Example 19-7. Destructor Example |
<?php
class MyDestructableClass {
function __construct() {
print "In constructor\n";
$this->name = "MyDestructableClass";
}
function __destruct() {
print "Destroying " . $this->name . "\n";
}
}
$obj = new MyDestructableClass();
?>
|
|
Like constructors, parent destructors will not be called implicitly by
the engine. In order to run a parent destructor, one would have to
explicitly call parent::__destruct() in the destructor
body.
Note:
Destructor is called during the script shutdown so headers are always
already sent.
Note:
Attempting to throw an exception from a desctructor causes a fatal error.
Autoloading Objects
