模板方法模式

抽象角色: 实现算法的轮廓/框架
具体角色: 实现算法的具体步骤
环境角色: 略
实现方法: 1. 纯虚函数+RTTI
         2. 纯虚函数+模板继承
         3. 纯虚函数+动态继承

#include <iostream>
/* 虚函数--运行时识别 */
class CBase {
public:
    int loop(ssize_t counts) {
        while (-1 == counts || 0 == counts--) {
            func();
        }
        return 0;
    }
    virtual void func(void) = 0;
};

class CDerive: public CBase {
public:
    inline void func(void) {
        std::cout << "virtual-derive" << std::endl;
    }
};

/* 虚函数--编译时识别 */
template<typename derive>
class CBase {
public:
    int loop(ssize_t counts) {
        while (-1 == counts || 0 == counts--) {
            func();
        }
        return 0;
    }
    inline void func(void) {
        return downcast()->func();
    }
protected:
    inline derive* downcast(void) {
        return static_cast<derive* > (this);
    }
    inline const derive* downcast() const {
        return static_cast<const derive* > (this);
    }
};
class CDerive: public CBase<CDerive> {
public:
    inline void func(void) {
        std::cout << "template-derive" << std::endl;
    }
};

/* 虚函数--编译时识别 */
template<typename base>
class CDerive: public base {
public:
    int loop(ssize_t counts) {
        while (-1 == counts || 0 == counts--) {
            func();
        }
        return 0;
    }
    inline void func(void) {
        return base::func();
    }
};
class CBase {
    inline void func(void) {
        std::cout << "template-derive" << std::endl;
    }
};