State Machine Presentation1 61

The State Pattern

Thursday, March 18, 2010

The State PatternAn Appalling Exploration


?


?














:)


Why we need it...


B. F. Skinner(do not do what he did)



Skinner box“Operant

Conditioning Chamber”



FAIL


What you do depends on your state


Blood test



Blood test

NotThing



Blood test

NotThing

Thing



Firstaid


Firstaid

NotThing



Firstaid

NotThing

Thing



Firstaid

NotThing

Thing

Blood test

NotThing

Thing


Firstaid

NotThing

Thing

Blood test

NotThing

Thing


1. Repeatedly using same test

2. Answers to test are predictable and repeated

3. Test concerns one’s own internal matters


Time to get practical.



public class Creature{ public function Creature() { trace(“Ecce Creature”); }}



1. Come to life


1. Come to life2. Talk to us


1. Come to life2. Talk to us3. Move around


public class Creature{

public function Creature() { trace(“Ecce Creature”); }

public function zap() {}

public function talk() {}

public function walk() {} }


public class Creature{

public function Creature() { trace(“Ecce Creature”); }

public function zap() {}

public function talk() {}

public function walk() {} }





... public function implant( b : Brain ) { mybrain = b; }...



public function zap() { // IF DEAD, BECOME ALIVE // IF ALIVE, BECOME DEAD

}

public function walk() {

}

public function talk() { }



}

public function talk() { // IF DEAD, DO NOTHING // IF ALIVE, DESCRIBE CANCER CURE

} public function walk() {

}



}

public function talk() { // IF DEAD, DO NOTHING // IF ALIVE, DESCRIBE CANCER CURE

}

public function walk() { // IF DEAD, DO NOTHING // IF ALIVE, WALK TO LAB

}


x_x


o_o


0.0


x_x


?



public class Creature{ private var amIdead : Boolean;

public function Creature() { trace(“Ecce Creature”); amIdead = true;

}

public function zap() { if( amIdead ) { amIdead = false;

} else

{ amIdead = false;

}}

public function talk() { if( amIdead ) { // DO NOTHING -- I’M DEAD

} else

{ trace(“Listen to this...”); trace(“the secrets of eternity”);

}}

public function walk() { if( amIdead ) { // DO NOTHING -- I’M DEAD

} else

{ trace(“I’ll go to my lab”); trace(“and cure cancer”);

}}

}




}


} else

{ amIdead = false;

}}


} else


}}


} else


}}

}




}


} else

{ amIdead = false;

}}


} else


}}


} else


}}

}




}


} else

{ amIdead = false;

}}


} else


}}


} else


}}

}Thursday, March 18, 2010

[clip: Igor drops Hans Delbruck’s brain]



public class Creature{ private var amIdead : Boolean; private var doIHaveDelbruckBrain : Boolean;


}

public function implant( b : Brain ) { mybrain = b; if( mybrain == DELBRUCK_BRAIN ) // how?? { doIHaveDelbruckBrain = true; } else { doIHaveDelbruckBrain = false; } }


} else

{ amIdead = false;

}}


} else

{ if( doIHaveDelbruckBrain ) {

trace(“Listen to this...”); trace(“the secrets of eternity”); } else { trace(“UNNNNNNNH”); }

}


keynote:/Users/pbalogh/Documents/StateMachinePresentation/StateMachinePresentation62_end.key















}



} else

{ amIdead = false;

}}


} else



}

















}



} else

{ amIdead = false;

}}


} else



}

















}



} else

{ amIdead = false;

}}


} else



}

















}



} else

{ amIdead = false;

}}


} else



}















Business

State Machine Presentation1 61