Norman Hutchinson. Emerald: An Object-Oriented Language for Distributed Programming. PhD thesis, Department of Computer Science, University of Washington, January 1987.  Home/Search   Document Not in Database   Summary   Related Articles   Check

.... of the Scandinavian school is [54] the use of undisciplined code reuse is critizised in [35] Slide 56 59 The problems of inheritance, subtyping, and recursion are exposed in [33, 14, 15, 5] The separation of subtyping and inheritance is made clear in [32] Slide 58 Emerald is described in [6, 50, 7, 87]; Trellis Owl in [95] Slide 60 62 Definitions of class based inheritance are given in [57, 49, 110, 46, 63, 96, 9, 93] Annotated Bibliography 103 Slide 63 66 The soundness of covariance in Eiffel is questioned in [34] the soundness of the pure Simula version is argued in [60] Slide 67 ....

Norman Hutchinson. Emerald: An Object-Oriented Language for Distributed Programming. PhD thesis, Department of Computer Science, University of Washington, January 1987.

....for loadbalancing purposes. Mapping object models onto concurrent systems has progressed from a point where the chief support for distribution was through remote procedure calls [Bir85] and message passing libraries [BRT ] to the current state of the art distributed programming languages [Hut87, Lis88, KMN 90, MGNS91] Language support for distribution has considerable advantages over that provided by either of the other two approaches since: ffl It is the only technique which, with the help of good semantic analysis, can help to transparently partition an application. ffl It can ....

....the constraint expression graph has the minimal number of conflicts. As mentioned earlier, this work is not directly related to object clustering and instead concentrates on resource allocation. Hence, it is not possible to draw a comparison between it and our work directly. Emerald: Emerald [Hut87, ABL86] is a general purpose programming language and kernel which was the first to implement the notion of a conformance based type system. It supports an atypical variant of the object oriented paradigm CHAPTER 2. RELATED WORK 15 through delegation, prototypes and active objects. Emerald ....

Norman C. Hutchinson. Emerald: An Object Oriented Language for Distributed Programming. PhD thesis, University of Washington at Seattle, January 1987.

....in [CW85] That paper also included a very extensive discussion of types and subtypes in object oriented languages. The failure of bounded polymorphism using subtyping to capture the constraints needed in examples like our binary search tree example above was first pointed out in [CCH 89] and [Hut87] In [CCH 89] the authors invented a generalization of bounded polymorphism, called F bounded quantification, which provided the correct constraints on polymorphism. F bounded quantification 35 TypeFunction BinSearchTreeType(T # Comparable) ObjectType function find(T) Boolean; ....

....methods function find(elt: T) Boolean begin if root nil then . if elt.equal(current.getValue( then . end; procedure insert(newElt: T) function isEmpty( Boolean begin return (root = nil) end end class; Figure 17: BinSearchTree classes. 37 language Emerald [BHJL86, BHJ 87, Hut87] The language School ( RIR93] also constrains polymorphism with a mechanism similar to F bounded quantification. Interestingly, the type restrictions obtained by match bounded polymorphism are equivalent to those obtained by mechanisms for restricting type parameters in ADT style languages ....

N. Hutchinson. Emerald: An object-oriented language for distributed programming. PhD thesis, University of Washington, 1987.

....a safety loop hole [5] The latest version of Eiffel requires system level type checking , which gives up on local type checkability and sometimes rejects dynamically type safe programs. Because of these problems, 6] suggested that subtyping should be clearly separated from subclassing. Emerald [11] is one of the few languages that actually implemented this separation. In Emerald, however, the result is a significant burden on the programmer. Often, subtyping and subclassing do go along in parallel, and Emerald requires separate specification even for this common case. Later language ....

Norman Hutchinson. Emerald: An Object-Oriented Language for Distributed Programming. PhD thesis, Department of Computer Science and Engineering, University of Washington, Seattle, WA, January 1987.

....is a suitable argument for emptySet.of , since the result of that invocation is a homogeneous set in which the = operation is applied only to objects of the same type as the target. We have emphasized this point at such length for several reasons. First, although we first observed in reference [Hutchinson 87, Section 3.8] that conformity is not the appropriate relation to bound a type 14 parameter, our overloading of the symbol ffi has probably led to confusion. Second, other authors have also used the same symbol for parameter constraints and for their subtyping relation. For example, America ....

Norman Hutchinson. Emerald: An Object-Oriented Language for Distributed Programming. PhD thesis, Department of Computer Science, University of Washington, January 1987.

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