设计模式之责任链模式

#include <string>
class Context {
public:
    std::string name;
    int day;
};
class LeaveRequest {
public:
    // 随着判断的增加，LeaveRequest类变得不稳定
    bool HandleRequest(const Context &ctx) {
        if (ctx.day <= 3)
            HandleByMainProgram(ctx);
        else if (ctx.day <= 10)
            HandleByProjMgr(ctx);
        else
            HandleByBoss(ctx);
    }
private:
    bool HandleByMainProgram(const Context &ctx) {
    }
    bool HandleByProjMgr(const Context &ctx) {
    }
    bool HandleByBoss(const Context &ctx) {
    }
};

#include <string>
class Context {
public:
    std::string name;
    int day;
};
class IHandler {
public:
    virtual ~IHandler() {}
    void SetNextHandler(IHandler *next) {
        next = next;
    }
    bool Handle(ctx) {//具体的流程还有条件也可以抽象
        if (CanHandle(ctx)) {
            return HandleRequest();
        } else if (GetNextHandler()) {
            return GetNextHandler()->HandleRequest(ctx);
        } else {
            // err
        }
    }
protected:
    virtual bool HandleRequest(const Context &ctx) = 0;
    virtual bool CanHandle(const Context &ctx) =0;
    IHandler * GetNextHandler() {
        return next;
    }
private:
    IHandler *next;
};
class HandleByMainProgram : public IHandler {
protected:
    virtual bool HandleRequest(const Context &ctx){
        //
    }
    virtual bool CanHandle() {
        //
    }
};
class HandleByProjMgr : public IHandler {
protected:
    virtual bool HandleRequest(const Context &ctx){
        //
    }
    virtual bool CanHandle() {
        //
    }
};
class HandleByBoss : public IHandler {
public:
    virtual bool HandleRequest(const Context &ctx){
        //
    }
protected:
    virtual bool CanHandle() {
        //
    }
};
int main () {
    IHandler * h1 = new MainProgram();
    IHandler * h2 = new HandleByProjMgr();
    IHandler * h3 = new HandleByBoss();
    h1->SetNextHandler(h2);
    Context ctx;
    h1->handle(ctx);
    return 0;
}