PHP: Can I Use Fields In Interfaces?

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

Late answer, but to get the functionality wanted here, you might want to consider an abstract class containing your fields. The abstract class would look like this:

abstract class Foo{    public $member;}

While you could still have the interface:

interface IFoo{    public function someFunction();}

Then you have your child class like this:

class bar extends Foo implements IFoo{    public function __construct($memberValue = "")    {        // Set the value of the member from the abstract class        $this->member = $memberValue;    }    public function someFunction()    {        // Echo the member from the abstract class        echo $this->member;    }}

There's an alternative solution for those still curious and interested. :)

Use getter setter. But this might be tedious to implement many getters and setters in many classes, and it clutter class code. And you repeat yourself!

As of PHP 5.4 you can use traits to provide fields and methods to classes, ie:

interface IFoo{    public function DoSomething();    public function DoSomethingElse();    public function setField($value);    public function getField();}trait WithField{    private $_field;    public function setField($value)    {        $this->_field = $value;    }    public function getField()    {        return $this->field;    }}class Bar implements IFoo{    use WithField;    public function DoSomething()    {        echo $this->getField();    }    public function DoSomethingElse()    {        echo $this->setField('blah');    }}

This is specially usefull if you have to inherit from some base class and need to implement some interface.

class CooCoo extends Bird implements IFoo{    use WithField;    public function DoSomething()    {        echo $this->getField();    }    public function DoSomethingElse()    {        echo $this->setField('blah');    }}