通过在函数调用中构造的引用传递对象

Question

we use some functions like this:

std::string const & GetValue(std::string const & val) {
return val;
}

Is there a way to break compilation if a user is passing a temporary, because the code is sometimes misused using function calls like the following:

std::string const & abc = GetValue(std::string("Value"));

And is there a difference (regarding the lifetime of the passed object) if the return value is not assigned to a reference, but to an object?

std::string def = GetValue(std::string("Value"));

Thanks a lot!

Answer 1

You could add a deleted rvalue overload to prohibit binding to rvalues entirely:

void GetValue(std::string && val) = delete;

Alternatively, you could make the rvalue overload return a prvalue, thus avoiding dangling references:

std::string GetValue(std::string && val) { return GetValue(val); }