Re: How to make code accepting differet types work?

"Victor Bazarov" <>
Wed, 12 Jul 2006 09:13:48 -0400
Jim Langston wrote:

"Ian Collins" <> wrote in message

Jim Langston wrote:

This is something I've been thinking about creating, and am trying
to get the pieces together.

I want to be able to assign values in a method accepting different
types. I.E.

MyInstance.MyMethod("IntField") = 1;
MyInstance.MyMethod("FloatField") = 2.34f;
MyInstance.MyMethod("StringField") = std::string("Hello");

Is this possible?

Assign to what?

Could you use a map and have something like MyInstance["IntField"] =

MyInstance will, in fact, have a map, but the values will be
std::string. If I was using method overloading it would be something
like (untested code):

void MyInstance::MyMethod( std::string key, int value )
  std::map<std::string, std::string>::iterator it = MyMap.find(key);
  if ( it != MyMap.end() )
     it.second = jml::StrmConvert( value );

StrmConvert is a template that uses stringstream to convert between
types, in this case to a std::string.

Yes, I know I can actually use this, but I would prefer to use
operator= as it just seems more natural to me.

I didn't see the beginning of the conversation, but here is my take on
what you're asking about (as I understand it):
#include <string>
#include <map>

class MyClass {
    std::map<std::string,int> i;
    std::map<std::string,float> f;
    std::map<std::string,std::string> str;
    class MyProxy {
        MyClass& mc;
        std::string key;
        MyProxy(MyClass& m, std::string const& k) : mc(m), key(k) {}
        void operator =(int i) { mc.i[key] = i; }
        void operator =(float f) { mc.f[key] = f; }
        void operator =(std::string const &s) { mc.str[key] = s; }

    MyProxy MyMethod(std::string const& k) {
        return MyProxy(*this,k);

int main() {
    MyClass MyInstance;
    MyInstance.MyMethod("OneInt") = 0;
    MyInstance.MyMethod("TwoInt") = 42;
    MyInstance.MyMethod("OneFloat") = 1.0f;
    MyInstance.MyMethod("TwoFloat") = 3.14159f;
    MyInstance.MyMethod("OneString") = "blah";
    MyInstance.MyMethod("TwoString") = "blahblah";



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