Strategy
The Strategy pattern is a behavioral design pattern that enables you to define a group of algorithms, encapsulate each one in its own class or function, and allow them to be used interchangeably.
Let’s describe a hypothetical example in the RPG game. Where reward for a quest will depend on the reputation of a player. Players with a low reputation will get a reward of 50%, players with mid-reputation will get a reward of 100%, and players with a high reputation will get a reward of 150%.
Player class
---@class Player
---@field public reputation number
local Player = {}
Player.__index = Player
---@param reputation number
---@return Player
function Player:new(reputation)
local t = {
reputation = reputation or 1
}
return setmetatable(t, self)
end
return Player
QuestReward class and its strategies
The strategies are defined in the QuestReward class only for simplicity reasons. This can be created as separate classes or functions.
---@class QuestReward
---@field public player Player
local QuestReward = {
lowReputationStrategy = function(reputation)
return reputation * 0.5
end,
midReputationStrategy = function(reputation)
return reputation * 1
end,
hightReputationStrategy = function(reputation)
return reputation * 1.5
end,
}
QuestReward.__index = QuestReward
---@param player Player
---@param gold number
---@return QuestReward
function QuestReward:new(player, gold)
if player.reputation < 5 then
return self.lowReputationStrategy(gold)
elseif player.reputation < 10 then
return self.midReputationStrategy(gold)
else
return self.hightReputationStrategy(gold)
end
end
return QuestReward
Usage
local Player = require("Player")
local QuestReward = require("QuestReward")
local player01 = Player:new(15)
print(QuestReward:new(player01, 100)) -- 150
local player02 = Player:new(7)
print(QuestReward:new(player02, 100)) -- 100
local player03 = Player:new(1)
print(QuestReward:new(player03, 100)) -- 50
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