策略模式Lua實現

策略模式Lua實現

Strategy = {}

ConcreteStrategyA = {}

ConcreteStrategyB = {}

ConcreteStrategyC = {}

Context = {strategy = nil}

function Strategy:new(o)
 o = o or {}
 setmetatable(o,self)
 self.__index = self
 return o;
end

function Strategy:AlgorithmInterface()
 print("邏輯接口")
end

ConcreteStrategyA = Strategy:new()

function ConcreteStrategyA:AlgorithmInterface()
 print("具體策略A")
end

function Context:new(o,s)
 o = o or {}
 setmetatable(o,self)
 self.__index = self
 if s ~= nil then
  o.strategy = s
 end
 return o;
end

function Context:ContextInterface()
 self.strategy:AlgorithmInterface()
end

context = Context:new({},ConcreteStrategyA:new())
context:ContextInterface()

上面的代碼的輸出結果是：具體的策略A

如果你把

function ConcreteStrategyA:AlgorithmInterface()

注釋掉，輸出的結果應該就會是：邏輯接口。

有興趣的同學也可以將ConcreteStrategyB,ConcreteStrategyC加上去，練練手。

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