c++ -智能指针-在模板内强制转换智能指针

我在工作中有一个复杂的代码库，我创建了一个小示例来模拟问题，下面是代码。

& lt;下面的代码供参考> -这段代码是可编译的，如果我们有boost库和FastDelegate.h与项目链接。如果您需要完整的可编译示例项目，请告诉我，我可以给您发电子邮件。

我有两个问题需要帮忙解决。

如下面的代码所示，我有一个具有参数类型的类作为另一个类对象的模板。现在，当我在UserClass的构造函数(第107行)中初始化下面的类时，我得到错误，因为mBaseAcceptor是一个具有基类类型模板参数的类，但我需要做mBaseAcceptor (new derivedAcceptor_t)。铸造问题如何解决这个问题?

这里是

./boost/smart_ptr/shared_ptr.hpp:387:9: error: comparison between distinct pointer types ‘Acceptor<DerivedClass>*’ and ‘Acceptor<BaseClass>*’ lacks a cast

1. 另一个问题是在第108行，即使我神奇地说通过使用派生类的另一个受体来解决这个问题，这就是我使用mDerivedAcceptor的地方，在第108行我做

   mDerivedAcceptor->SetDelegate(fastdelegate::MakeDelegate(this, &UserClass::HandleDelegate)); 
   

然后出现错误输入

"error no matching function call for HandleDelegate(DerivedClass&, bool). 

这是有意义的，因为HandleDelegate有BaseClass类型的参数，并且通过存储一个委托(这是一个函数)。Ptr)，我们必须用适当的参数调用函数。但是如何解决这个问题呢?

1. 如果我用派生类在接受器类内转换处理程序，当我只传递baseClass指针时，它会工作吗?

/*
 * smart_pointer_1.cpp
 *
 *  Created on: Jul 26, 2011
 *      Author: balaji
 */
#include <algorithm>
#include <boost/foreach.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/shared_ptr.hpp>
#include "FastDelegate.h"
#include <iostream>
using namespace std;
template <class Handler>
class Acceptor {
public:
    typedef fastdelegate::FastDelegate1<Handler &, bool> delegate_t;
    Acceptor ();
    void Initialize(Handler *&handle);
    void SetDelegate(delegate_t delegate) { mDelegate = delegate; }
private:
   int mValues[2];
    delegate_t mDelegate;
};
template <class Handler>
Acceptor<Handler>::Acceptor()
{
    std::cout << "In Constructor: " << __FUNCTION__ << std::endl;
    mValues[0] = 1;
    mValues[1] = 2;
}   
template <class Handler>
void Acceptor<Handler>::Initialize(Handler *&handle){
    if (!handle) {
        std::cout << __FUNCTION__ << " : created" << std::endl;
        handle = new Handler();
    } else {
        std::cout << __FUNCTION__ << " : Error exception" << std::endl;
    }
    if (mDelegate && mDelegate(*handle)) {
        std::cout << "Ok Called Handle in " << __FUNCTION__ << std::endl;
    } else {
        std::cout << "Not Called Handle in " << __FUNCTION__ << std::endl;
    }
   handle->displayComputer();
}
class BaseClass {
    std::string mComputer;
public:
    BaseClass() {
    std::cout << "In Base Constructor: " << __FUNCTION__ << std::endl;
    mComputer = "Mac";
    }
    virtual void displayComputer() {
    std::cout << "Computer type is " << mComputer << std::endl;
    }
};
class DerivedClass : public BaseClass {
    std::string mLanguage;
public:
    DerivedClass() {
    std::cout << "In Derived Constructor: " << __FUNCTION__ << std::endl;
    mLanguage = "C++";
    }
    void displayComputer() {
    std::cout << "Language is " << mLanguage << std::endl;
    }
};
class UserClass {
public:
    UserClass();
    UserClass(bool);
    typedef Acceptor<BaseClass> baseAcceptor_t;
    typedef Acceptor<DerivedClass> derivedAcceptor_t;
    typedef boost::shared_ptr<BaseClass> basePtr_t;
    void CallDelegate(BaseClass&);
private:
    boost::shared_ptr<baseAcceptor_t> mBaseAcceptor;
    boost::shared_ptr<derivedAcceptor_t> mDerivedAcceptor;
    BaseClass *mConnBasePtr;
    bool HandleDelegate(BaseClass& baseDelegate);
};
UserClass::UserClass() : mBaseAcceptor(new baseAcceptor_t)
{
    std::cout << "In Constructor: " << __FUNCTION__ << std::endl;
    mBaseAcceptor->SetDelegate(fastdelegate::MakeDelegate(this, &UserClass::HandleDelegate));
    mBaseAcceptor->Initialize(mConnBasePtr);
}
UserClass::UserClass(bool value)
{
    std::cout << "In Constructor: " << __FUNCTION__ << std::endl;
    mBaseAcceptor.reset(new derivedAcceptor_t);         //    <<========== Problem Here because of improper casting
    mBaseAcceptor->SetDelegate(fastdelegate::MakeDelegate(this, &UserClass::HandleDelegate));   //   <<=== Also here because of improper type passed to MakeDelegate function ptr. Please note HandleDelegate has an argument of type BaseClass, but Acceptor is derived class
    mBaseAcceptor->Initialize(mConnBasePtr);
}

bool UserClass::HandleDelegate(BaseClass& baseDelegate)
{
    std::cout << "In " << __FUNCTION__ << std::endl;
    return true;
}

int main() {
    std::cout << "In function: " << __FUNCTION__ << std::endl;
    typedef boost::shared_ptr<UserClass> userPtr_t;
    userPtr_t user(new UserClass(true));
    std::cout << "In function: " << __FUNCTION__ << " at end "<< std::endl;
    return 0;
}