Tag Archives: oop

PHP: Don’t Call the Destructor Explicitly

micro tutorial, PHP, , , , , , , , ,

“PHP 5 introduces a destructor concept similar to that of other object-oriented languages, such as C++”[1] says the documentation for destructors, but let’s see the following class.

class A
{
	public function __construct()
	{
		echo 'building an object';
	}
 
	public function __destruct()
	{
		echo 'destroying the object';
	}
}
 
$obj = new A();

Well, as you can not call the constructor explicitly:

$obj->__construct();

So we should not call the destructor explicitly:

$obj->__destruct();

The problem is that I’ve seen this many times, but it’s a pity that this won’t destroy the object and it is still a valid PHP code.
Continue reading PHP: Don’t Call the Destructor Explicitly →

OOP JavaScript: Accessing Public Methods in Private Methods

javascript, micro tutorial, web development, , , , , , , , , , , , , ,

As you know in JavaScript when you define a variable with the special word “var” the scope of this variable is within the function. So when you simply wite “var a = 5” the variable named “a” has a global scope and can be accessed in any function in the global scope.

var a = 5;
 
function f() { return a; } // returns 5

Thus f will return the value of “a” which equals to 5. You can also change the value of the global variable in the function body.

var a = 5;
function f() { a = 10; return a; }
console.log(a); // equals to 10

Now after we call the function f the value of “a” will equal to 10. This is because we reference the global variable “a” into the function body without using the keyword “var”. This means that if you put the “var” keyword the variable “a” inside the function body is no longer the same variable as the variable defined outside the body. It becames “local” and it’s visible only inside the function.
Continue reading OOP JavaScript: Accessing Public Methods in Private Methods →

Object Oriented JavaScript: Inheritance

web development, , , , , , , , , , , , , , , , , , ,

Objects and JavaScript

JavaScript, being a functional language, differs from most of the procedural/object oriented languages we know. The object oriented approach in JavaScript is rather strange. However there is much power in making objects! The syntax is really odd and there are several approaches.

Literal Notation

As many of you may know the most used notation is the JSON (JavaScript Object Notation).

{ 'key1' : 'val1'
, 'key2' : 'val2'
, 'key3' : 'val3'
}

Of course this is the very basic example. You can use as value any JavaScript object – another similar object or a function.

{ 'key1' : 'val1'
, 'key2' : { 'inner_key1' : 'inner_val1' }
, 'key3' : function() {
			return 10 + 5;
		 }
}

The two examples above are showing an anonymous object in JavaScript, but you can assign this code to some variable.

var myObject = 
	{ 'key1' : 'val1'
	, 'key2' : 'val2'
	, 'key3' : 'val3'
	}

or

var myObject =
	{ 'key1' : 'val1'
	, 'key2' : { 'inner_key1' : 'inner_val1' }
	, 'key3' : function() {
				return 10 + 5;
			 }
	}

and then you can call the properties of these objects with the ‘.’ operator:

myObject.key1;
myObject.key2.inner_key1;
myObject.key3();

So far so good – this is the literal object notation in JavaScript. However there is another “objects” in JavaScript.
Continue reading Object Oriented JavaScript: Inheritance →