call signature Represents the interface of a callable object. A call signature includes the return type and a comma-separated list of argument types enclosed in parentheses.
class-type conversion Conversions to or from class types are defined by constructors and conversion operators, respectively. Non
explicit constructors that take a single argument define a conversion from the argument type to the class type. Conversion operators define conversions from the class type to the specified type.
conversion operator A member function that defines a conversions from the class type to another type. A conversion operator must be a member of the class from which it converts and is usually a
const member. These operators have no return type ...