Question

I have an enum StackIndex defined as follows:

typedef enum 
{
    DECK,
    HAND,
    CASCADE1,
    ...
    NO_SUCH_STACK
} StackIndex;

I have created a class called MoveSequence, which is a wrapper for a std::deque of a bunch of tuples of the form <StackIndex, StackIndex>.

class MoveSequence
{
    public:
        void AddMove( const tpl_move & move ){ _m_deque.push_back( move ); }
        void Print();
    protected:
    deque<tpl_move> _m_deque;
};

I thought I could create a static std::map member of the MoveSequence class, which would translate a StackIndex to a std::string, for use by the Print() function. But when I tried, I got the error:

"error C2864: 'MoveSequence::m' : only static const integral data members can be initialized within a class"

If its not possible to created a std::map as a static member, is there another way to create a std::map that translates a StackIndex to a std::string that can be used to print out MoveSequence objects?

thanks

Beeband.

Answer 1

You can make a std::map a static member of the class. What you can’t do is initiliaze it within the class definition. Note that this is what the error is telling you:

error C2864: ‘MoveSequence::m’ : only static const integral data members can be *initialized* within a class

So, you want to have this in the header:

class MoveSequence
{
    static std::map<StackIndex, std::string> _m_whatever;
};

And then in a source (.cpp) file you want this:

std::map<StackIndex, std::string> MoveSequence::_m_whatever( ..constructor args.. );