How to overload both directions of an assignment operator in C++?

Question

I have a weird union I am using for alignment reasons.

I have overloaded it so that it can be assigned a string value.

Now I wish to overload the = operator so that I can assign it TO a string value.

union Tag
{
    std::string * path;
    long id;
};
struct TextureID
{
    Tag ID;
    int type;

    TextureID& operator= (std::string str){ ID.path = new std::string(str); type=0; }
    TextureID& operator= (long val){ ID.id = val; type=1; }
};

In this case we have overloaded the operators such that

TextureID t = "hello";

Is a valid statement.

How may I overwrite the = operator to be able to do:

string s = t;

Answer 1

You can create a conversion operator to convert your TextureID to a std::string

operator std::string() const {
    // logic to create a string to return
}

or create an explicit function to do the conversion

std::string to_string() const {
    // logic to create a string to return
}