Supporting explicit disambiguation of multi-methods

Abstract

Multiple inheritance and multiple dispatching are two sources of ambiguities in object-oriented languages. Solving ambiguities can be performed automatically, using techniques such as totally ordering the supertypes of each type or taking the order of the methods' arguments into account. Such implicit disambiguation has the drawback of being difficult to understand by the programmer and hiding programming errors. Conversely, solving ambiguities can be left up to the explicit intervention of the programmer. The most common explicit disambiguation technique consists in defining new methods for ambiguous invocations. However, finding ambiguities and adding as few methods as possible is a difficult task, especially in multi-method systems. In this report, we show that there always exists a unique minimal set of method redefinitions to explicitly disambiguate a set of multimethods. We propose an algorithm to compute the minimal disambiguation set, together with explanations: for each method that is to be added, the programmer is given the set of methods that caused the ambiguity. Key

Surveying Rule Inheritance in Model-to-Model Transformation Languages.

“…To actually implement this derived property, algorithms for explicit disambiguation in the area of multi-methods may be applied. For instance, in [AD96] an algorithm is proposed, which calculates a minimal set of method redefinitions necessary for disambiguation. This algorithm consists of two steps.…”

A Comparison of Rule Inheritance in Model-to-Model Transformation Languages

“…In TGGs, a run-time error is thrown. It must be noted that, in the area of multi-methods, there are approaches for explicit disambiguation (e.g., [3] proposes a minimal set of method redefinitions necessary for disambiguation) which could be reused in transformation languages. The diamond problem in multiple inheritance does not apply to ATL, since multiple inheritance is not supported.…”

Representing Matrices Using Multi-Directional Foreign Functions

“…Multi-argument functions enhance the expressive power of the data model but the type checker must include algorithms for type resolution of tuple types [2] and for handling ambiguities [1].…”

“…When resolvent (2) is chosen the system will be solved using the LDL T decomposition, while a trivial diagonal solution method is used for case (1). The optimizer translates the query into the algebra tree in Fig.…”

“…Multi-argument functions require generalized type resolution methods compared to the type resolution of pure object-oriented methods [1,2]. In the database context the issue is not mainly fast type resolution when looking up methods but rather optimizing queries with expanded function definitions (views) in order to detect hidden search paths and multi-directional function inverses [8].…”