How Triangle Law and
Parallelogram law of addition of
Vectors are different?Ain't they.

Please don't tell me the things
written in book......give me the
appropriate reason.And how do i distinguish between the two while adding vectors,what am i trying to say is i get really confused where to use parallelogram law and where triangle law

P.s:my basics are really weak though!May be the question might not be right


Question: Roguelike Class Structure Makes Everything Effectively Global
Answer: I've been designing my roguelike framework on and off for the past few years and I come to think that the traditional OOP approach doesn't provide a very useful abstraction for a typical roguelike world for the reasons that you mentioned - everything is so interdependent on each other that each class may potentially need to know about every other class. 

For example, AI routines should logically be a part of the Creature class, but AI potentially needs to know everything - the current dungeon map, the state of PC's quests, current World events etc. Even implementing simplest actions such as moving isn't straightforward: do you have a Creature.move(x,y) method and require every Creature object to know its current dungeon level, OR you have a DungeonLevel.moveCreature(creature, x, y) method? What if monsters in your game can move from one dungeon level to another - do you need an even higher level method, e.g. World.moveCreature(creature, dungeonLevel, x, y) ?

So in the end I decided to simply make most functions global, instead of agonizing over the correct location of each method in the class hierarchy, and use classes mostly as data structures. Now my Creature object doesn't have to link back to the parent object, and it contains only simplest code that doesn't need to be aware of other classes.