#############
# Initial state we have an extension Thing with a method draw
#############
/////////////
// Core
/////////////
/**
 * Thing that can draw
 */
interface Thing {

	/**
	 * @param int $x
	 */
	public function draw( $x );
}

/**
 * Trait used to ease evolution of the Thing interface
 */
trait ThingBCTrait {
}

/**
 * Base class for Thing
 */
abstract class BaseThing implements Thing {
	use ThingBCTrait;
}

/////////////
// Extension
/////////////

class SimpleThing extends BaseThing {

	/**
	 * @param int $x
	 */
	public function draw( $x ) {
		print( $x );
	}
}

class ThingAndThat extends That implements Thing {
	use ThingBCTrait;

	/**
	 * @param int $x
	 */
	public function draw( $x ) {
		print( $x );
	}
}


####################
# Goal 1: warn extensions that they need to implement draw2
# Goal 2: gently tell call sites to move to draw2
# We introduce draw2 as a replacement of draw
# We soft deprecate draw to gently warn call sites
# We add draw2 with a warning to our BCTrait to not break existing extensions
####################
/////////////
// Core
/////////////
/**
 * Thing that can draw
 */
interface Thing {

	/**
	 * @param int $x
	 * @deprecated use draw2d
	 */
	public function draw( $x );

	/**
	 * @param int $x
	 * @param int $y
	 */
	public function draw2d( $x, $y );
}

/**
 * Trait used to ease evolution of the Thing interface
 */
trait ThingBCTrait {
	public function draw2d( $x, $y ) {
		wfDeprecated( __CLASS__ . " must implement draw2d" );
		$this->draw( $x );
	}
}

/**
 * Base class for Thing
 */
abstract class BaseThing implements Thing {
	use ThingBCTrait;
}

/////////////
// Extension
/////////////

class SimpleThing extends BaseThing {

	/**
	 * @param int $x
	 */
	public function draw( $x ) {
		print( $x );
	}
}

class ThingAndThat extends That implements Thing {
	use ThingBCTrait;

	/**
	 * @param int $x
	 * @deprecated
	 */
	public function draw( $x ) {
		// We can implement our own BC strategy
		$this->draw2d( $x, 12 );
	}

	public function draw2d( $x, $y ) {
		print( "$x:$y" );
	}
}


#######################
# We finally remove draw from Thing
# We keep a hard deprecation warning for draw in ThingBCTrait in case some old call sites are still using it
# The Thing interface is now what we expect
# Extensions that want to be compatible with a old MW core version can keep their old draw method.
#######################


/////////////
// Core
/////////////
/**
 * Thing that can draw
 */
interface Thing {

	/**
	 * @param int $x
	 * @param int $y
	 */
	public function draw2d( $x, $y );
}

/**
 * Trait used to ease evolution of the Thing interface
 */
trait ThingBCTrait {
	public function draw( $x ) {
		wfDeprecated( __METHOD__ . " is deprecated" );
		$this->draw2d( $x, 0 );
	}
}

/**
 * Base class for Thing
 */
abstract class BaseThing implements Thing {
	use ThingBCTrait;
}

/////////////
// Extension
/////////////

class SimpleThing extends BaseThing {

	/**
	 * @param int $x
	 * @param int $y
	 */
	public function draw2d( $x, $y ) {
		print( "$x:$y" );
	}
}

class ThingAndThat extends That implements Thing {
	use ThingBCTrait;

	/**
	 * @param int $x
	 * @deprecated
	 */
	public function draw( $x ) {
		// We can implement our own BC strategy
		$this->draw2d( $x, 12 );
	}

	public function draw2d( $x, $y ) {
		print( "$x:$y" );
	}
}