Integrated implementation of dynamic untyped object-based operator overloading

Operator overloading, a popular mechanism in the C++ language, is a form of ad hoc polymorphism on operator functions, allowing alternative implementations for different argument types. Classless languages with untyped objects are languages that lack classes and treat all objects as compliant to a common Object type. Languages in this category are flexible, dynamic, and easy‐to‐use, with popular examples being JavaScript, Lua, and ActionScript (the latter being hybrid by also offering classes). This paper presents an integrated implementation of untyped operator overloading which enable users to handle dynamically the full range of operators on objects. The focus is on features not supported by other languages, such as (i) arithmetic and relational operators allowing to separately handle caller lhs and rhs positions; (ii) an assignment operator with an untyped analogy of type casting; (iii) a slot access operator allowing user‐defined policies for editing object slots; and (iv) a function‐call operator to support functors. Operators are treated as first‐class object slots, distinguished by reserved indices that match the respective operator lexemes. All reported techniques have been applied in implementing the operator overloading features of the Delta language. Copyright © 2010 John Wiley & Sons, Ltd.