In PHP, can I specify an interface to have fields, or are PHP interfaces limited to functions?
<?php
interface IFoo
{
public $field;
public function DoSomething();
public function DoSomethingElse();
}
?>
If not, I realize I can expose a getter as a function in the interface:
public GetField();
You cannot specify members. You have to indicate their presence through getters and setters, just like you did. However, you can specify constants:
interface IFoo
{
const foo = 'bar';
public function DoSomething();
}
See http://www.php.net/manual/en/language.oop5.interfaces.php
Interfaces are only designed to support methods.
This is because interfaces exist to provide a public API that can then be accessed by other objects.
Publicly accessible properties would actually violate encapsulation of data within the class that implements the interface.
You cannot specify properties in an interface : only methods are allowed (and make sense, as the goal of an interface is to specify an API)
In PHP, trying to define properties in an interface should raise a Fatal Error : this portion of code :
interface A {
public $test;
}
Will give you :
Fatal error: Interfaces may not include member variables in...