Function template with an operator

Question

In C++, can you have a templated operator on a class? Like so:

class MyClass {
public:
    template
    T operator()() { /* return some T */ }         


        

Answer 1

You're basically right. It is legal to define templated operators, but they can't be called directly with explicit template arguments.

If you have this operator:

template 
T operator()();

as in your example, it can only be called like this:

int i = c.operator()();

Of course, if the template argument could be deduced from the arguments, you could still call it the normal way:

template 
T operator()(T value);

c(42); // would call operator()

An alternative could be to make the argument a reference, and store the output there, instead of returning it:

template 
void operator()(T& value);

So instead of this:

int r = c.operator()();

you could do

int r;
c(r);

Or perhaps you should just define a simple get() function instead of using the operator.