Question

I am trying to make a configuration manager class, that can store arbitrary objects by std::string.

My starting idea for my interface (abstract base class) was this (of course this is horribly incomplete)

class ConfigurationManager
{
public:
   static boost::shared_ptr<ConfigurationManager> create();

   template<typename T>
   virtual T getOption(const std::string& name) = 0;
};

But then my compiler pointed out that template’s cannot be virtual(and then I realized that I cannot have exported templates anyways).

Internally I am going to be using boost::any’s(pretty much a runtime checked void*), but I do not want to expose boost::any in my interface.

What would be the best way to go about this?

Answer 1

Make a protected virtual abstract function returning boost::any, and a non-virtual, non-abstract, public template function to hide it from the users of your interface.

class ConfigurationManager {
protected:
    virtual boost::any getOptionProtected(const std::string& name) = 0;
public:
    static boost::shared_ptr<ConfigurationManager> create();
    template<typename T> T getOption(const std::string& name) {
        return boost::any_cast<T>(getOptionProtected(name));
    }
};