C++;示例观察者模板类错误 我在Windows上用C++创建了观察模板样例。
这里有一个代理人,他有一份客户名单。每当代理的实体(变量x)发生更改时,它都会通知其客户,并将x的值传递给客户。然后,客户将该值存储在各自的变量中 在下面的代码中,代理作为主体,客户作为观察者。 代理是从其代理模板类创建的,客户是从其客户模板类创建的C++;示例观察者模板类错误 我在Windows上用C++创建了观察模板样例。,c++,templates,observer-pattern,C++,Templates,Observer Pattern,这里有一个代理人,他有一份客户名单。每当代理的实体(变量x)发生更改时,它都会通知其客户,并将x的值传递给客户。然后,客户将该值存储在各自的变量中 在下面的代码中,代理作为主体,客户作为观察者。 代理是从其代理模板类创建的,客户是从其客户模板类创建的 template <typename T> class customer // acts as base observer class { char name[50]; public:
template <typename T>
class customer // acts as base observer class
{
char name[50];
public:
customer()
{
cout << __FUNCTION__ "(): " << "DEFAULT CONS\n";
}
customer(char* nm)
{
strcpy_s(name, nm);
cout << __FUNCTION__ "(): " << "name set to " << name << "\n";
}
char * getName()
{
return(name);
}
virtual void update(int c)
{
}
};
class customerC: public customer<customerC>
{
int c;
public:
customerC()
{
cout << __FUNCTION__ "(): " << "DEFAULT customerc cons\n";
}
customerC(char* nm):customer<customerC>(nm)
{
cout << __FUNCTION__ "(): " << "customer is " << getName() << "\n";
}
void update(int val)
{
cout << __FUNCTION__ "(): c to " << c << "\n";
c = val;
}
};
class customerD: public customer<customerD>
{
int d;
public:
customerD()
{
cout << __FUNCTION__ "(): " << "DEFAULT customerd cons\n";
}
customerD(char* nm):customer<customerD>(nm)
{
cout << __FUNCTION__ "(): " << "customer is " << getName() << "\n";
}
void update(int val)
{
cout << __FUNCTION__ "(): c to " << d << "\n";
d = val;
}
};
template<typename T>
class agent
{
char name[50];
int x;
protected:
vector<customer<T>*> custList;
public:
agent()
{
cout << __FUNCTION__ "(): " << "DEFAULT agent cons\n";
}
virtual void setx(int c)
{
cout << __FUNCTION__ "(): " << "Setting x to " << c << "\n";
//// x = c;
//// notifyObs();
}
virtual void getx()
{
cout << __FUNCTION__ "(): " << "x = " << x << "\n";
}
void addCust(customer<T>* cobj)
{
cout << __FUNCTION__ "(): " << "Adding customer " << cobj->getName() << " to list.\n";
custList.push_back(cobj);
}
void showCust()
{
cout << __FUNCTION__ "(): " << "Customers are:\n";
if(custList.empty())
cout << "\n\nYou have no items.";
else
{
vector<customer<T>*>::iterator cs;
for(cs = custList.begin(); cs != custList.end(); ++cs)
{
cout << (*cs)->getName() << "\n";
}
}
}
int notifyObs()
{
cout << __FUNCTION__ "(): " << "Customers notified are:\n";
if(custList.empty())
cout << "\n\nYou have no items.";
else
{
vector<customer<T>*>::iterator cs;
for(cs = custList.begin(); cs != custList.end(); ++cs)
{
cout << (*cs)->getName() << "\n";
(*cs)->update(x);
}
}
return 0;
}
};
class agentS: public agent<agentS>
{
int x;
public:
agentS()
{
cout << __FUNCTION__ "(): " << "DEFAULT agentS cons\n";
}
void setx(int c)
{
cout << __FUNCTION__ "(): " << "Setting x to " << c << "\n";
x = c;
notifyObs();
}
void getx()
{
cout << __FUNCTION__ "(): " << "x = " << x << "\n";
}
};
int _tmain(int argc, _TCHAR* argv[])
{
customerC cobj("c1");
customerD dobj("c2");
agentS agS;
agS.addCust(cobj);
//// agS.addCust<customer<customerC>>(cobj);
//// agS.addCust(dobj);
agS.showCust();
agS.setx(4);
return(0);
}
模板
类customer//充当基本观察者类
{
字符名[50];
公众:
客户()
{
cout通过这样创建代理类,addCust的有效签名变为void addCust(customer*cobj);
。但是,您的客户类没有在代理类型上模板化(实际上似乎没有理由对其进行模板化)
您似乎将动态多态性(客户继承和虚拟函数)和静态多态性(创建一种客户类型向量的模板)混合在一起。这些选项中的任何一个单独使用都更有意义:
动态多态性(继承)。通过存储基类指针,您可以在同一容器中存储不同类型的客户,并使用客户基类和虚拟函数以相同的方式处理它们:
struct customer {};
struct customerC : customer {};
struct customerD : customer {};
struct agent
{
void addCust(customer* customer) { ... }
std::vector<customer*> custList;
};
int main()
{
agent a;
customerC c;
a.addCust(&c);
}
struct-customer{};
结构customerC:customer{};
结构customerD:customer{};
结构代理
{
void addCust(客户*customer){…}
std::向量列表;
};
int main()
{
代理人a;
顾客c;
a、 addCust&c;
}
静态多态性(模板)。代理类以客户类型为模板,因此向量只能包含一种类型的客户,但很容易为任何给定的客户类型创建特定的代理:
struct customer {};
struct customerC : customer {};
struct customerD : customer {};
template<CustomerT>
struct agent
{
void addCust(CustomerT* customer) { ... }
std::vector<CustomerT*> custList;
};
int main()
{
agent<customerC> a;
customerC c;
a.addCust(&c);
}
struct-customer{};
结构customerC:customer{};
结构customerD:customer{};
模板
结构代理
{
void addCust(CustomerT*customer){…}
std::向量列表;
};
int main()
{
代理人a;
顾客c;
a、 addCust&c;
}
错误的直接原因是addCust
需要一个指针,但cobj
不是指针。对我来说,不清楚应该在哪里进行更改以使它们匹配。
struct customer {};
struct customerC : customer {};
struct customerD : customer {};
struct agent
{
void addCust(customer* customer) { ... }
std::vector<customer*> custList;
};
int main()
{
agent a;
customerC c;
a.addCust(&c);
}
struct customer {};
struct customerC : customer {};
struct customerD : customer {};
template<CustomerT>
struct agent
{
void addCust(CustomerT* customer) { ... }
std::vector<CustomerT*> custList;
};
int main()
{
agent<customerC> a;
customerC c;
a.addCust(&c);
}