E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proceedings European Conference on Object-Oriented Programming (ECOOP'91), volume 512 of Lecture Notes in Computer Science, pages 167--179. Springer-Verlag, 1991.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....as described here is a refinement of earlier versions of ZEST published in [5] and [4] The syntax of the language is mainly borrowed from Object Z ( 9] however, the semantics is entirely different. It also incorporates the notion of subtyping, theoretical details of which may be found in [6]. 5.1 Extensions of Z ZEST is an extension of the formal language Z. The Z language is getting widely accepted as a formal notation for specifying systems. However, it is not modular enough a characteristic which makes tracking of pieces of information in a large text rather difficult. To ....

....going on now over the last few years. Promoting the use of object oriented Z for ODP concepts were reported in ( 7, 8] while contributions on the use of Z for specifying managed objects appeared in ( 12] A main technical contribution to the development of a BT version of object oriented Z is [6], in which a semantics for subtyping inheritance in object oriented Z is formulated. 5.3 Use of ZEST ZEST has been used in specifying the ISO ITU s managed objects as defined using the templates given in the Guidelines for the Definition of Managed Objects (GDMO) 11] The experience is recorded ....

E Cusack, Inheritance in Object-Oriented Z, in P America (ed), ECOOP '91, European Conference on Object-Oriented Programming, LNCS 512, Springer-Verlag 1991.

....variables) to all values (including object values) in the program. Methods of all objects operate on the global state and encapsulation is only assumed. Behavioural dependencies in the presence of subclassing have also been 30 studied in various extensions of Z specification languages, e.g. [24, 14], but only between class specifications and not implementations. By having specification constructs as part of the (extended) programming language, we do not have to treat specifications and implementations separately. Data refinement of modules, abstract data types, and abstract machines as, ....

E. Cusack. Inheritance in object-oriented Z. In P. America, editor, Proceedings of ECOOP'91, LNCS 512, pages 167--179, Geneva, Switzerland, July 15-19 1991. Springer-Verlag. 32

.... Z [She95, Dil94, Hay87, Spi92] and VDM [She95, Jon86] These include Hall s style [Hal90b] and chapter three of [SBC92] ZERO [WM90] and chapter four of [SBC92] MooZ [Mei91] Object Z [DDK 90] and chapter six of [SBC92] OOZE [Ale91] Schuman and Pit [SPB90] Z [Lan90, Lan95] ZEST [Cus91] Hyper Z [Mau92] and VDM [LG96] A number of the above are reviewed in [SBC92] and [LH93] CHAPTER 2. RELATED WORK 39 In this section we shall review a selection of these. They can be split into two groups: object based and object oriented. The object based ones are: Hall s style, ZERO, ....

Elspeth Cusack. Inheritance in object oriented Z. Lecture Notes in Computer Science, 512:167--182, 1991.

.... has been described as an operator on classes (Snyder 1991) As such, it enables the creation of new classes through the technique commonly referred to as incremental modification (Wegner and Zdonik 1988; Cook and Palsberg 1989; 11 Wegner 1990; Lenzeri, Nardi, and Simi 1991; Snyder 1991; Cusack 1991), whereby a new class is defined by modifying an existing one. In other words, given a modifier Mod, containing the characteristics to be added, redefined, or excluded, the mechanism transforms an existing parent entity Par into the resulting entity Res. This process can be modelled using ....

.... (Coplien 1992) ffl partial inheritance (Nierstrasz 1989) ffl selective inheritance (Al Haddad, George, and Samadzadeh 1991) ffl abstract inheritance (Royer 1992) 18 ffl specification inheritance (Snyder 1991) ffl is kind of inheritance (Wirfs Brock and Johnson 1991) ffl derivation (Cusack 1991); ffl parameterised and full operational inheritance (Faulstich Brady 1993) ffl implementation inheritance (Pun and Winder 1989) ffl spaghetti inheritance (Avotins and Mingins 1993) ffl haphazard inheritance (Armstrong and Mitchell 1994) ffl facility inheritance (Meyer 1994) The ....

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Cusack, E. (1991). Inheritance in object oriented Z. In P. America (Ed.), Proceedings of ECOOP'91, Geneva, Switzerland, pp. 165--179. Springer-Verlag.

....Jonathan Bowen PRG TR 10 92 Delta Oxford University Computing Laboratory 11 Keble Road, Oxford OX1 3QD Select Z Bibliography Jonathan Bowen Abstract This document gives an up to date list of Z references. A version of this bibliography is due appear in the Proceedings of the Z User Workshop, York 1991, edited by John Nicholls, in the Springer Verlag Workshops in Computing series. Further copies of this Technical Report may be obtained from the Librarian, Oxford University Computing Laboratory, Programming Research Group, 11 Keble Road, Oxford OX1 3QD, England (Telephone: 44 865 273837, ....

Elspeth Cusack. Inheritance in object oriented Z. In Pierre America, editor, Proc. ECOOP'91 European Conference on Object-Oriented Programming, volume 512 of Lecture Notes in Computer Science, pages 167--179. SpringerVerlag, 1991.

....is Object Z [CDD 90] DKRS91] developed at the University of Queensland, Australia. This adds a class structure to Z and extends the schema inclusion facilities of Z to classes. This gives a facility similar to inheritance. Subtyping in ObjectZ has been explored by Duke [Duk92] and by Cusack [Cus91] Typically, for subtyping to hold between two classes, the preconditions (postconditions) of the subclass schemas must be equivalent or weaker (stronger) than those of the supertype schemas. The subclass invariant can be stronger than the superclass invariant, but must not be strengthened so ....

Elspeth Cusack. Inheritance in object-oriented Z. In Pierre America, editor, ECOOP '91: European Conference on Object-Oriented Programming, pages 167-- 179. Springer-Verlag, 1991. Ref. on page 28.

....based on type specifications whether one type is a subtype of another. Meyer uses America s pre and post condition rules for Eiffel [30] although here the pre and post conditions are given operationally, by providing a program to check them, rather than assertionally. Cusack s approach [7] also relates specifications; her rule defines subtyping in terms of strengthening state invariants. However, neither author considers the problems introduced by extra mutators nor the preservation of history properties. Therefore, they allow certain subtype relations that we forbid (e.g. ....

Elspeth Cusack. Inheritance in object oriented z. In Proceedings of ECOOP '91, 1991.

....methods, but also on their behavior. Our work is most similar to that of America [Ame91] who has proposed rules for determining based on type specifications whether one type is a subtype of another. Meyer [Mey88] also uses pre and postcondition rules similar to America s and ours. Cusack s [Cus91] approach of relating type specifications defines subtyping in terms of strengthening state invariants. However, none of these authors considers neither the problems introduced by extra mutators nor the preservation of history properties. Therefore, they allow certain subtype relations that we ....

Cusack, E. Inheritance in object oriented Z. In Proceedings of ECOOP '91. Springer-Verlag, 1991.

....[Lea89] The simulation relations defined in [Lea89] do not have any provision for mutation. Similarly other model theoretic approaches [BW90, LW90, LP92, LW95] do not deal with mutation and aliasing. So none of these approaches study the relation between aliasing and behavioral subtyping. Cusack [Cus91] has a notion of specialization that is similar to behavioral subtyping. Though her class schemas allow extra methods in the subtype and seem to deal with mutation, she does not study the relation between mutation, aliasing, and subtyping. Further, she requires the types of the arguments for the ....

....Introducing history constraints in their subsumption relations would be allow such reasoning and we believe that their notion of subsumption would then be equivalent to strong behavioral subtyping that is restricted to relations between structural subtypes. 3.11.1. 3 Cusack s Specialization Cusack [Cus91] defines a notion of specialization over schemas of Z [Spi88] that is like behavioral subtyping. Since she uses schemas to define the specialization both the subtypes and the supertypes should be specified in the same schema. Further, she does not deal with the subtyping in the extra arguments of ....

E. Cusack. Inheritance in object oriented Z. In Pierre America, editor, Proceedings of the European Conference on Object-Oriented Programming (ECOOP), Geneva Switzerland, Lecture Notes in Computer Science, pages 167--179, volume 512, Springer-Verlag, New York, N.Y., 1991.

....to the semantics given by the Z model. Object comprehensions present a declarative specification of the desired results of a query, it would be important to show how these relate to the constraints and invariants in the semantics of the data model. 5. 3 Object oriented features in Z Cusack in [23] and Alencar and Goguen in [4] alter the Z specification language to introduce objectoriented features. Z can then be used to formally specify some object oriented system. This is not quite the same as the articles above that specify the OO data model in some formalism. Extending Z to include OO ....

....objectoriented features. Z can then be used to formally specify some object oriented system. This is not quite the same as the articles above that specify the OO data model in some formalism. Extending Z to include OO concepts, however, does involve a formal treatment of those concepts. Cusack [23] deals with inheritance. Two types of inheritance are introduced into the Z formalism, derivation and subtyping inheritance. Derivation is the technique of adding methods and or attributes to an existing class to create a new class; this is also known as incremental inheritance. This type of ....

[Article contains additional citation context not shown here]

Elspeth Cusack. Inheritance in object oriented Z. In Lecture Notes in Computer Science, volume 512. Springer-Verlag, 1991. ECOOP '91 European Conference on Object-Oriented Programming.

....no longer works. 6 This approach was suggested to me in personal communication by James Power, Dublin City University. 3. 4 Context dependent abbreviation If we take the attitude that a procedure can only see the locally declared attributes and those of its superclasses as in ObjectZ [12, 10] and Z [16] then 1(p) can be expanded context dependently, depending on the visibility of the variables. For example, in class B, 1(p) asserts (q 0 = q) while in methods of class D it says (q 0 = q r 0 = r) Unfortunately, this approach still does not deal with examples such as those ....

Cusack, E., "Inheritance in object-oriented Z", Proc. ECOOP'91, Springer Verlag LNCS #512, pp.167-179

....subtype relationships, and gives the specifier more flexibility. Therefore although such a method specification could be used in a strong behavioral subtype according to our definition, it would not yield a strong behavioral subtype according to Liskov and Wing s original definition. Cusack [5] defines specialization, which is like behavioral subtyping. Specialization does not handle subtyping on additional arguments and does not have any notion of history constraints. As in our work, her definition uses a simulation function and does not constrain a subtype s method outside the domain ....

E. Cusack. Inheritance in object oriented Z. In Pierre America, editor, Proceedings of the European Conference on Object-Oriented Programming (ECOOP), Geneva Switzerland, volume 512 of Lecture Notes in Computer Science, pages 167--179, New York, N.Y., 1991. SpringerVerlag.

....subtype relationships, and gives the specifier more flexibility. Therefore although such a method specification could be used in a strong behavioral subtype according to our definition, it would not yield a strong behavioral subtype according to Liskov and Wing s original definition. Cusack [5] defines specialization, which is like behavioral subtyping. Specialization does not handle subtyping on additional arguments and does not have any notion of history constraints. As in our work, her definition uses a simulation function and does not constrain a subtype s method outside the domain ....

E. Cusack. Inheritance in object oriented Z. In Pierre America, editor, Proceedings of the European Conference on Object-Oriented Programming (ECOOP), Geneva Switzerland, Lecture Notes in Computer Science, pages 167--179, New York, N.Y., 1991. Springer-Verlag.

....identifies these methods that behave differently; thus, finer subtyping distinctions can be made when behavioral information is used in addition to signature information. The inclusion of the type constraint is what distinguishes the Liskov and Wing work from all others (e.g. America [1] Cusack [3], Leavens [4, 7] that also include some kind of behavioral information. To foreshadow what is coming in the next section: Not only must a supertype s type invariant and methods be preserved by the subtype s, but so must its type constraint. The type constraint is intended to capture certain kinds ....

Elspeth Cusack. Inheritance in object oriented Z. In Proceedings of ECOOP '91. Springer-Verlag, 1991.

....however, cannot be established in Z as this corresponds to writing predicates on the specification itself. 6.3.2.9 Subtype supertype: Subtyping supertyping on template types can be defined as extension in Z. First we need to introduce some notation. We summarise the results we need from [11, 13]. Every mathematical expression in a Z specification has either a basic type t (that is, it is a member of a given set of the specification) or a composite type. There are three kinds of composite type: set types P t (describing sets) cartesian product types t 1 Theta : Theta t k ....

Elspeth Cusack, Inheritance in object oriented Z, ECOOP 91.

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E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proceedings European Conference on Object-Oriented Programming (ECOOP'91), volume 512 of Lecture Notes in Computer Science, pages 167--179. Springer-Verlag, 1991.

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Elspeth Cusack. Inheritance in Object Oriented Z. In Proceedings of the European Conference on Object-Oriented Programming (ECOOP), Geneva, July 1991. Published as Lecture Notes in Computer Science (LNCS) 512:167-179, SpringerVerlag, 1991.

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E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proc. ECOOP'91 European Conference on Object-OrientedProgramming,volume 512 of Lecture Notes in Computer Science, pages 167--179. Springer-Verlag, 1991.

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E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proc. ECOOP'91 European ConferenceonObject-OrientedProgramming,vol- ume 512 of Lecture Notes in Computer Science, pages 167--179. SpringerVerlag, 1991.

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Z.E. Cusack. Inheritance in object oriented z. In European Conference on Object-Oriented Programming, pages 167-179, 1991.

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Elspeth Cusack, Inheritance in object oriented Z, ECOOP 91.

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E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proc. ECOOP'91 European Conference on Object-Oriented Programming, volume 512 of Lecture Notes in Computer Science, pages 167--179. Springer-Verlag, 1991.

No context found.

Elspeth Cusack, Inheritance in object oriented Z, ECOOP 91.

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E. Cusack. Inheritance in object oriented Z. In P. America, editor, Proc. ECOOP'91 European Conference on Object-Oriented Programming, volume 512 of Lecture Notes in Computer Science, pages 167--179. SpringerVerlag, 1991.

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