Question

I am a new in terms of PHP OOP programming, i don’t understand when and how the following class names are and when shall i use them :

$a = new Classname();
$a = new Classname;

$a = ClassName::function();
$a = ClassName::getInstance();

Many thanks and sorry for silly question:

Answer 1

These are identical.

$a = new Classname();
$a = new Classname;

You can use them interchangeably when the class constructor does not take, or does not require other parameters.

Example:

class Classname
{
    public function __construct($var = null)
    {
        // ..
    }

    static public function getInstance()
    {
        // ..
    }
}

In this case you can use $a = new Classname; and $var will take the default value, or $a = new Classname('hello') and $var will be equal to the value passed.

---

These are both static method calls.

$a = ClassName::function();
$a = ClassName::getInstance();

One calls a method called “function” (which cannot exist – it is a reserved word), the other calls a method named “getInstance”. When you use them really depends on what the methods do.

Static methods can be called without creating an object instance.

I.e.

Classname::staticMethod();

versus

$obj = new Classname;
$obj->method;