Changing return type of a function without template specialization. C++

c++, return, templates

Solution

This can be done with a conversion function

struct proxy {
    string str;
    proxy(string const &str):str(str) { }
    template<typename T> operator T() { 
        return boost::lexical_cast<T>(str); 
    }
};

proxy parse(string const &str) { return proxy(str); }

Now you just need to do

float a = parse("3.1");

And it should work well. Incidentally, you may just use the class directly. I recommend renaming it to `conversion_proxy` to point to the fact that it's just a proxy to a happening conversion but that it itself doesn't do conversion

struct conversion_proxy {
    string str;
    conversion_proxy(string const &str):str(str) { }
    template<typename T> operator T() { 
        return boost::lexical_cast<T>(str); 
    }
};

float a = conversion_proxy("3.1");

Problem

I was wondering if it is possible to change the return type of a function based on the type of variable it is being assigned to. Here's a quick example of what I mean. I want to create a function that parses a variable of int, bool, or float from a string. For example... ``` Int value = parse("37"); Float value = parse("3.14"); Bool value = parse("true"); ``` I understand if I make this function a template, that the variable type must be determined from the argument list which is always going to be a string. Is there any other way of doing this with c++?

Original source