Question

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();

Answer 1

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