List of Command

From:
Peter_APIIT <peterapiit@gmail.com>
Newsgroups:
comp.lang.c++.moderated
Date:
Wed, 5 Aug 2009 14:06:15 CST
Message-ID:
<8aeac2a2-9564-452a-b1b9-5b9a65579047@j9g2000prh.googlegroups.com>
I wrote a command pattern to my class Administrator, HR and Staff.
Each of it has several MF but command only operate on single MF.
Therefore, i got this design.

I got the solution like this. CommandList composes Vector of command.

Quote:
class GenericCommander;
class ComamndList : public GenericCommander {};
class Command : public GenericCommander {};
This approach works with single command and list of command.

Code:

class GenericCommand
{
public:
    GenericCommand();
    virtual ~GenericCommand();

    virtual void ExecuteSignalCallBack(int) = 0;

};

template <typename T>
class Command : public GenericCommand
{
public:
    typedef boost::shared_ptr<T> objectPtr;

private:

    objectPtr targetObjectCommandCallerPtr;

    void (T::*MemberFuncPtr)();

public:
    Command();
    explicit Command(objectPtr& );
    ~Command();

    void ExecuteSignalCallBack(int);

};

template <typename T>
Command<T>::Command() : targetObjectCommandCallerPtr(objectPtr())
{
}
// =========================================
template <typename T>
Command<T>::Command(objectPtr& user)
    : targetObjectCommandCallerPtr(objectPtr(user))
{
}
// =========================================
template <typename T>
Command<T>::~Command()
{
}
// =========================================
template <typename T>
void Command<T>::ExecuteSignalCallBack(int choice)
{
    (*targetObjectCommandCallerPtr.*MemberFuncPtr)();
}

template <typename T>
class Command;

template <typename T>
class CommandList : public GenericCommand
{
public:
    typedef boost::shared_ptr<T> objectPtr;

private:
    Command<T> cont[15];

public:
    CommandList();
    explicit CommandList(objectPtr&);

    ~CommandList();

    void ExecuteSignalCallBack(int);
    // void CallCommand(int );

};

// =========================================
template <typename T>
CommandList<T>::CommandList()
    : cont(Command<T>())
{
}
// =========================================
template <typename T>
CommandList<T>::CommandList(objectPtr& userTargetObjectPtr)
        : cont(Command<T>(userTargetObjectPtr))
{
}
// =========================================
template <typename T>
CommandList<T>::~CommandList()
{
}
// =========================================
template <typename T>
void CommandList<T>::ExecuteSignalCallBack(int choice)
{
    (cont[choice - 1].*MemberFuncPtr)();
}
// =========================================

*
    Not recommended to specialize
    Function Template
*/

// ============ General Command ============
template <typename T>
boost::shared_ptr<GenericCommander>
                CommandFactory(boost::shared_ptr<T>& targetObject,
                                                            void (T::*MemberFuncPtr)() )
{
    // To create one command only
}
// =========== Generic Command List =========
template <typename T>
boost::shared_ptr<GenericCommander> CommandListFactory
(boost::shared_ptr<T>& targetObject)
{

}
// =========== Administrator Command ========
template <>
boost::shared_ptr<GenericCommander> CommandListFactory<Administrator>
(boost::shared_ptr<Administrator>&
targetObject) void
(T::*MemberFuncPtr)() )
{
    // Regiter Administrator MF
    /*
        &Administrator::Add
        &Administrator::Delete
        &Administrator::Modified
    */
}
// ============= HR Command =================
template <>
boost::shared_ptr<GenericCommander> CommandListFactory<HumanResource>
(boost::shared_ptr<HumanResource>&
targetObject) void
(T::*MemberFuncPtr)() )
{
    // Regiter HR MF
}
// ============== Staff Command ============
template <>
boost::shared_ptr<GenericCommander> CommandListFactory<Staff>
(boost::shared_ptr<Staff>&
targetObject) void
(T::*MemberFuncPtr)() )
{
    // Register Staff MF
}
// =========================================

1. What approach replaces function template specialization ?
2. How to implement the CommandFactory ?

Usage Code:
share_ptr<GenericCommander> GCPtr = CommandFactory(thePtr);

GCPtr->ExecuteSignalCallBack(int);

Thanks for your help.

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