different types in the same map

JonLT

Hi, trying to add scripting support for a game i'm making.
I'd like to be able to add an arbitrary type to any object in the game, and i'm using a base class with maps to hold the types. Currently a have a map for every known type (bool, int, float, double and some templates), but i'd like to have just one map to hold them all. This is what i got so far:

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//adds a variable to the map with with the name 'name' and the value 'value'

template <typename T>

void add(const char* name, T value)

{

     if( typeid(T) == typeid(int) )

        ints[name] = value;
 
     if( typeid(T) == typeid(float) )

        floats[name] = value;
 
    //ect..

}

ints and floats are maps of the type

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std::map<const char*, int>

std::map<const char*, float>

but i'd like to have a function like this

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template <typename T>

void add(const char* name, T value)

{

    attributes[name] = value;

}

but i can't figure out how the map should be declared or how to get things out of the map without knowing the type.

Is this at all understandable? Does anyone have an idear for a solution?
Should i just settle with have to have a map for every type?

JonLT

Ok, no need to answer. I'v settled with the one map per type solution

weaknessforcats

Quote:

Originally Posted by JonLT

//adds a variable to the map with with the name 'name' and the value 'value'
template <typename T>
void add(const char* name, T value)
{
if( typeid(T) == typeid(int) )
ints[name] = value;

if( typeid(T) == typeid(float) )
floats[name] = value;

//ect..
}

Try not to do this. This is not what typeid is for plus every time you have a new T you have to change this template.

Your map is a map of pairs and probably would be declared as:

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map<char*, T> attributes;

JonLT

just to update a bit this is what i'm doing (left the typeid thing)

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template <class T>

class AttributeMap

{

    public:
 
        //! Gets a value from the map passed

        static T get(const std::map<const char*, T>& map, const char* name)

        {

            T tmp;

            typename std::map<const char*, T>::const_iterator it;

            for(it = map.begin(); it != map.end() ; it++)

            {

                if(it->first == name) //value found in map

                    tmp = it->second;

            }
 
            return tmp;

        }

};

and when i want to get something from a map i use it like this

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AttributeMap<float>::get(floatMap, floatName);

where float map is a std::map<const char*, float> and floatName is the key (a c-style string)

and when a add something to a map i do the usual

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floatMap[floatName] = value

This works fine, althoug my compiler tells me that "tmp might be used uninitialized in this function"

weaknessforcats

Quote:

Originally Posted by JonLT

This works fine, althoug my compiler tells me that "tmp might be used uninitialized in this function"

Yes. That's because tmp is declared and not initialized. There is no guarantee that the loop will be entered. If so, the function returns the uninitialized tmp.

This warning is based on the type used to specialize the function template. In this case a float. Were you to use a class that had a default constructor and copy constructor, you would get no warning.

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