c++ 设计模式 策略模式

最初版本

enum TaxBase
{
	CN_Tax,
	US_Tax,
	DE_Tax
};

class SalesOrder
{
	TaxBase tax;
public:
	double CalcaulateTax()
	{
		if (tax == CN_Tax)
		{

		}
		else if (tax == US_Tax)
		{

		}
		else if (tax == DE_Tax)
		{

		}
	}
};

最终版本

class TaxStrategy
{
public:
	virtual double Calculate(const Context& contxt) = 0;
	virtual	~TaxStrategy(){}
};

class CNTax : public TaxStrategy
{
public:
	virtual double Calculate(const Context& contxt)
	{

	}
};

class USTax : public TaxStrategy
{
public:
	virtual double Calculate(const Context& contxt)
	{

	}
};

class DETax : public TaxStrategy
{
public:
	virtual double Calculate(const Context& contxt)
	{

	}
};




class SaleOrder
{
private:
	TaxStrategy* strategy;
public:
	SaleOrder(StrategyFactory* strategyfactory)
	{
		strategy = strategyfactory->NewStrategy;
	}
	~SaleOrder()
	{
		delete strategy;
	}
	double CalculateTax()
	{
		Context context;
		double val = strategy->Calculate();
	}
};