Is it possible to take a parameter by const reference, while banning conversions so that temporaries aren't passed instead?

Question

Sometimes we like to take a large parameter by reference, and also to make the reference const if possible to advertize that it is an input parameter. But by making the refe

Answer 1

I think your example with int and long is a bit of a red herring as in canonical C++ you will never pass builtin types by const reference anyway: You pass them by value or by non-const reference.

So let's assume instead that you have a large user defined class. In this case, if it's creating temporaries for you then that means you created implicit conversions for that class. All you have to do is mark all converting constructors (those that can be called with a single parameter) as explicit and the compiler will prevent those temporaries from being created automatically. For example:

class Foo
{
    explicit Foo(int bar) { }
};