Barbara Liskov, Alan Snyder, Russell Atkinson, and Craig Schaffert. Abstraction mechanisms in CLU. Communications of the ACM, 20(8):564--576, August 1977.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....Prolog. Xerox PARC. Kahn86] 2 Other languages. The following languages are of interest, though they do not claim to be object oriented. Ada: Ada has user definable types and some data abstraction mechanisms. Ada83 Barn80 Bruno86] CLU: Programming language with data abstraction from MIT. [Lisk77] Alphard: Another language with some data abstraction. Shaw77] Modula: Descendent of Pascal with monitor like modules. Wirt83] 3 Applications. The following list includes work that employs object oriented concepts, and applications written in object oriented languages. AAIS: CAD environment ....

B. Liskov, A. Snyder, R. Atkinson and C. Scha#ert, "Abstraction Mechanisms in CLU", CACM, vol. 20, no. 8, pp. 564-576, Aug 1977.

....be hidden. The only legitimate interface to the object should be through its operations. Programming languages that support some form of data abstraction are growing in number quite rapidly, and are becoming difficult to enumerate. Some of these are : Simula [Birt73] Smalltalk [Gold83] CLU [Lisk77], Argus [Lisk83] Zetalisp [Wein81] C [Stro84] OOPC (Objective C) Cox83] Galileo [Alba85] Modula [Wirt83] Oz [Nier85a] Taxis [Mylo80] OPAL [Ahls84] Smallworld [Laff85] and BETA [Kris83] In Hybrid, ultimately everything is an object. The initiative to do things is also encapsulated in ....

B. Liskov, A. Snyder, R. Atkinson and C. Schaffert, "Abstraction Mechanisms in CLU", CACM, vol. 20, no. 8, pp. 564-576, August 1977.

....affect the final value of the whole execution. A method with multiple dispatch is an example of an overloaded function. 5. 2 Abstract Data Types and Existential Types Abstract Data Type declarations, from now on called ADT [Rey83, MP88] appear in typed programming languages like ADA, CLU, ML [LSS77, MMM91] This form of declaration binds a list of identifiers to a type with associated operations. We call this composite value a Data Algebra. The access to a data algebra is restricted to the explicit declared operations. Formally, a data algebra is a composed value, built from a set of ....

B. Liskov, A. Snyder, and C. Shaffert. Abstraction Mechanism in Clu. Communications of the ACM, (20):564--576, 1977.

....program invariants from unwanted external intervention. An abstract type is an ordinary type along with a set of operations; the structure of the type is hidden and the provided operations are the only ones authorized to manipulate objects of that type. This notion was well embedded in CLU [Liskov et al. 77] Liskov Guttag 86] and formed the basis for the later development of modular programming languages. This notion of abstraction is more restrictive than the general notion of algebraic abstract types [Futatsugi Goguen Jouannaud Meseguer 85] Polymorphism is the ability of a function to handle ....

B.H.Liskov et al.: Abstraction Mechanisms in CLU, Comm ACM 20,8, 1977.

....the most basic to the most complex entities. We will describe Smalltalk, and its contributions, in greater detail in Chapter 3. 2.1. 4 CLU CLU is a sequential, object oriented programming language designed to facilitate the construction of high quality programs through the use of abstraction [Liskov 77] The concept of levels of abstraction was introduced by Dijkstra in the T.H.E. system [Dijkstra 68] and integrated into the object model in collaboration with Hoare and Dahl [Dahl 72] The designers of CLU built upon this and related work in abstraction and type extensibility in programming ....

....failures without loss of information. Argus reflects a large body of earlier work by Liskov and her students in reliable software [Liskov 72] data abstraction in programming languages [Liskov 75] and distributed computing [Liskov 79b] The sequential programming language CLU [Liskov 79a, Liskov 77, Liskov 79c] forms the linguistic foundation on top of which Argus is built. Argus provides two principal extensions to CLU: actions and guardians. Actions An action is an activity that modifies some object (or objects) in the distributed system state atomically 8 . There are two properties ....

Barbara H. Liskov, Alan Synder, Russell Atkinson, and Craig Schaffert. Abstraction Mechanisms in CLU. Communications of the ACM, 20(8):564--576, August 1977.

.... abstraction languages were motivated by the software engineering concept of hiding information in modules [Parnas72] Early abstraction mechanisms were the SIMULA class concept [Birtwistle73] and Early s relational data structures [Early73] Some examples of current abstraction languages are CLU [Liskov77], ALPHARD [Shaw77] and SMALLTALK [Goldberg76] The abstraction concept has given a handle to program verification work in that abstraction can be verified and their formal semantics be used in verifying programs which use the abstraction [Flon79] Extensible Languages The goal of extensible ....

Liskov, B., Snyder, A., Atkinson, R., and Shaffert, C., Abstraction Mechanisms in CLU, Communications of the ACM, 20(8):564574, August, 1977.

....a number of distributed programs, such as a library information system, a distributed editor, and a mail repository. Status: The Argus research is active. Contact: Barbara Liskov, Massachusetts Institute of Technology, Laboratory for Computer Science, Cambridge, MA 02139 References: 52] 53] [54], 55] 56] 57] 58] 59] 60] 61] 62] 63] 64] 2.6 Athena Main Goal Project Athena is an educational experiment introduced in May 1983. It is a joint project of MIT, DEC and IBM to explore the potential uses of advanced computer technology in the university curriculum. Athena ....

B. Liskov, A. Snyder, R.R. Atkinson, and J.C. Schaffert, "Abstraction mechanisms in CLU", Communications of the ACM, 20(8):564--576, August 1977.

....Language The E language is a derivative of C [Kern78] with the addition of a set of programming constructs carefully chosen to provide high leverage to the DBI. A number of these constructs were inspired by developments in programming languages over the last 10 years, most notably, from CLU [Lisk77] and Pascal [Jens75] Its major features include the ability to bind a pointer variable to an object in a file, and to declare abstract data types in the spirit of CLU clusters. Program structure is fully modular, with separate compilation possible for all modules (including parameterized modules, ....

Liskov, B., Snyder, A., Atkinson, R., and Schaffert, C., "Abstraction Mechanisms in CLU", Comm. ACM, 20(8), August, 1977.

.... interactions by intercepting and modifying messages flowing between the components) It permits the design of a system using a component oriented methodology that decouples the type of a component (its specification or interface) from its implementation, so that the two can vary independently [17]. Interaction refinements are defined by wrapping the component type, using the Decorator pattern [15] A variation point (a context sensitive, dynamic join point see Section 3) manages the wrappers and decides, based on an externally specified composition policy, which wrappers (and thus, ....

Barbara Liskov, Alan Snyder, Russell Atkinson, and J. Craig Schaffert. "Abstraction Mechanisms in CLU." Communications of the ACM, vol. 20, no. 8, August 1977.

....a fixed structure, a forest of directed acyclic graphs, obtained by unrolling the aggregation (sub)graph corresponding to a portion of the schema of an object oriented database, such as 5. An iterator is a control abstraction used for the production of a sequence of values [14]. 15 Ode. Our concern is the flow of values, representing object ids, through this structure. Other work in GUI design theory studies the interaction with a user, using some dialog modes. Where possible, OdeView supports both the menu type (MM) and command language type (CLM) dialog modes ....

B. Liskov, A. Snyder, R. Atkinson and C. Schaffert, "Abstraction Mechanisms in CLU", Commun. ACM 20, 8 (Aug. 1977), .

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B. Liskov, A. Snyder, R. R. Atkinson, and C. Schaert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

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B. Liskov, A. Snyder, R. R. Atkinson, and C. Scha#ert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

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B. Liskov, A. Snyder, R. R. Atkinson, and C. Scha#ert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

....an upgrade and if a transform function reads such subobjects, then Condition E would be violated. But such upgrade are unlikely to happen in practice. Another reason Condition E may not hold is that an object might not encapsulate subobjects it depends on. This occurs in the case of iterators [43, 35] and other similar constructs. Consider, for example, an iterator over a set s. The iterator s job is to return a di erent element of the set each time its next method is called until all elements of the set have been returned. To do this job eciently, the iterator needs direct access to the ....

B. Liskov, A. Snyder, R. R. Atkinson, and C. Schaert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

....by encapsulating them inside data abstractions. 2.2. Linguistic Support for Data Abstraction Data abstractions are supported by linguistic mechanisms in several languages. The earliest such language was Simula 67 [3] Two major variations, those in CLU and Smalltalk, are discussed below. CLU [8][11] provides a mechanism called a cluster for implementing an abstract type. A template for a cluster is shown in Figure 2 1. The header identifies the data type being implemented and also lists the operations of the type; it serves to identify what procedure definitions inside the cluster can be ....

Liskov, B., Snyder, A., Atkinson, R. R., and Schaffert, J. C. "Abstraction mechanisms in CLU".Comm. of the ACM 20, 8 (August 1977), 564-576.

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Barbara Liskov, Alan Snyder, Russell Atkinson, and Craig Schaffert. Abstraction mechanisms in CLU. Communications of the ACM, 20(8):564--576, August 1977.

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B. Liskov, A. Snyder, R. Atkinson, and J. C. Scha#ert. Abstraction mechanisms in CLU. Communications of the ACM, 20(8):564--576, August 1977.

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Barbara Liskov, Alan Snyder, Russell R. Atkinson, and Craig Schaert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

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Liskov, B. / Snyder, A. / Atkinson, R. / Schaffert, C. "Abstraction mechanisms in CLU" From "Readings in object-oriented database systems (ed. Zdonik, S. B. / Maier, D.)" ISBN 055860 -000-0; Morgan Kaufmann publishers.

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Barbara Liskov, Alan Snyder, Russell Atkinson, Craig Schaert. Abstraction Mechanisms in CLU. Communications of the ACM (CACM) 20(8):564-576, August 1977.

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Barbara Liskov, Alan Snyder, Russell R. Atkinson, and Craig Scha#ert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

No context found.

Barbara Liskov, Alan Snyder, Russell R. Atkinson, and Craig Schaert. Abstraction mechanisms in CLU. In Communications of the ACM (CACM) 20(8), August 1977.

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B.H.Liskov et al.: Abstraction Mechanisms in CLU, Comm ACM 20,8, 1977.

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B. Liskov, A. Snyder, R. Atkinson, and J. C. Scha#ert. Abstraction mechanisms in CLU. Communications of the ACM, 20(8):564--576, August 1977.

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B.H.Liskov et al.: Abstraction Mechanisms in CLU, Comm ACM 20,8, 1977.

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