Is there a pattern for this?

Question

i have something that requires a matrix of values, similar to pokemon:

i have a class object for each of the types, is there a pattern or a good way to implement this, as a middle layer or in the classes?

Answer 1

Yes, give a try to the Decorator design pattern.

hint: just create a Normal class with all the stats you need. Then create a Decorator class for each row of the matrix: FireDecorator, SteelDecorator, that apply the multiplier for attack/defense.

bonus #1: you can build very easily a "Fire Steel Character", dynamically (the intent of the pattern)

bonus #2: when you add another character, say the "Giant", you just add one class, without touching anything else

Answer 2

You can use 2 maps (map in java, in other languages it can have another name): 1 for

Attacking-->Defending and one for Defending-->Attacking.

Let's consider Attacking-->Defending example. Map will contain Attacking types as keys and arrays of Defending types as values. For example:

Fire-->[Fire, Water, Grass, Ice, Bug, Rock, Dragon, Steel]

Answer 3

If you have a separate class for each "thing" that these types qualify (your pokemon or whatever) the classes could hold a static hash / map / dictionary structure that gives what multipliers there are for attacking the others. Such a hash would represent one row of the table. If you really need the reverse lookup, just make one more that stores the column of information.

Answer 4

A dictionary uses the names of the attacker (Fire, Ice etc) as key that contains dictionaries which use the names of the defender as keys and the multiplers as values.

Answer 5

It's a basic multiple-dispatch problem. Unfortunately, most languages do not support multiple dispatch.

So I would probably use a map of maps. The outer map maps attacks to maps of defenses, which in turn map defenses to scores/effects/whatever.

You could use the Visitor pattern, but that gets cumbersome fast.

In Python, assuming that you aren't using much subclassing (e.g. no subclasses of Ice), you could use a dictionary mapping (attack,defense) tuples to scores. That would be a rather clean solution and would be supported by a variety of languages (all you need is a Pair class and an ability to represent attack types as objects, either via a class object or something like an enum).

Answer 6

Why make it so complicated - For the sake of maintenance make it like it looks. A two dimensional array will do fine and since it is static will give you best lookup performance - You then just need a way to go from Name/Type to array index.