如何将携带模板的基类指向派生类，然后进行统一的操作呢
我们知道可以将基类指针指向不同的派生类，通过调用基类中的虚函数来实现代码架构的统一和简化。
可是如果基类中带有模板的话，应该怎样写才对呀，请不吝赐教！
//携带模板的基类定义
template <class TYPE>
class CBase
{
public:
virtual TYPE *Find(int lKey)
{
map<int, TYPE>::iterator iter;
iter = m_Map.find(lKey);
if (iter == m_Map.end())
{
printf("Not find\n");
return NULL;
}
else
{
cout << "Find it. val = " << iter->second << endl;
return &iter->second;
}
}
virtual TYPE *Insert(int lKey, TYPE val)
{
pair<map<int, TYPE>::iterator, bool> pr;
pr = m_Map.insert(pair<int, TYPE>(lKey, val));
if (!pr.second)
{
printf("Insert fail\n");
return NULL;
}
return &pr.first->second;
}
virtual void Delete(int lKey)
{
m_Map.erase(lKey);
}
public:
map<int, TYPE> m_Map;
};
//派生类1
class CDerive1: public CBase<int>
{
};
//派生类2
class CDerive2: public CBase<float>
{
};
//通过此类中的FindTbl获取指向不同派生类的基类指针，然后调用其虚函数进行操作
class CProc
{
public:
CBase *FindTbl(int lIndex)
{
if (1 == lIndex)
{
return &m_Tbl1; //这里编译不过
}
else if (2 == lIndex)
{
return &m_Tbl2;
}
else
{
return NULL;
}
}
public:
CDerive1 m_Tbl1;
CDerive2 m_Tbl2;
};
编译错误为：error C2440: 'return' : cannot convert from 'class CDerive1 *' to 'class CBase *'
[解决办法]
所以这里也不构成lz认为的同一个基类，不同的派生类：
class CDerive1: public CBase<int>
{
};
//派生类2
class CDerive2: public CBase<float>
{
};
CDerive1和CDerive2的基类是两个类，而不是一个类！
[解决办法]
下面的代码，供楼主参考：
#include <iostream>using namespace std;template<typename T>class Base{private: T base_t;public: Base(T t) { base_t = t; } virtual void printInfo() { cout << base_t << endl; }};template<typename T>class Derived1 : public Base<T>{private: T derived1_t;public: Derived1(T t):Base(t + 1) { derived1_t = t; } //可以去掉下面的注释试试 //void printInfo() //{ // cout << derived1_t << endl; //}};template<typename T>class Derived2 : public Base<T>{private: T derived2_t;public: Derived2(T t):Base(t + 2) { derived2_t = t; } //可以去掉下面的注释试试 //void printInfo() //{ // cout << derived1_t << endl; //}};int main(int argc, char** argv){ Base<int>* pb = new Base<int>(1); pb->printInfo(); pb = new Derived1<int>(1); pb->printInfo(); pb = new Derived2<int>(1); pb->printInfo(); delete pb; return 0;}
[解决办法]
#include <iostream>using namespace std;template <class T>class A{public: A(){} virtual void func(){} virtual ~A(){}};class B:public A<int>{public: B(){} virtual void func(){} virtual ~B(){}};class C:public A<float>{public: C(){} virtual void func(){} virtual ~C(){};};class D{public: template <class T> bool getObj(int index,A<T>* *ret) { if(index==1) { *ret=static_cast< A<int>* >(&b); return true; } else if(index==2) { *ret=static_cast< A<float>* >(&c); return true; } return false; }private: B b; C c;};int main(){ D d; A<int> *pB; A<float> *pC; if(d.getObj(1,&pB)) { pB->func(); } if(d.getObj(2,&pC)) { pC->func(); } if(!d.getObj(3,&pB)) //运行报错 { cout<<"index 3 not exists"<<endl; }/* A<double> *pNotExist; if(d.getObj(1,&pNotExist)) //编译报错 { }*/ return 0;}
[解决办法]