The diverse inheritance mechanisms provided by Smalltalk, Beta, and CLOS are interpreted as different uses of a single underlying construct. Smalltalk and Beta differ primarily in the direction of class hierarchy growth. These inheritance mechanisms are subsumed in a new inheritance model based on composition of mixins, or abstract subclasses. This form of inheritance can also encode a CLOS multiple-inheritance hierarchy, although changes to the encoded hierarchy that would violate encapsulation are difficult. Practical application of mixin-based inheritance is illustrated in a sketch of an extension to Modula-3.
{"title":"Mixin-based inheritance","authors":"Gilad Bracha, W. Cook","doi":"10.1145/97945.97982","DOIUrl":"https://doi.org/10.1145/97945.97982","url":null,"abstract":"The diverse inheritance mechanisms provided by Smalltalk, Beta, and CLOS are interpreted as different uses of a single underlying construct. Smalltalk and Beta differ primarily in the direction of class hierarchy growth. These inheritance mechanisms are subsumed in a new inheritance model based on composition of mixins, or abstract subclasses. This form of inheritance can also encode a CLOS multiple-inheritance hierarchy, although changes to the encoded hierarchy that would violate encapsulation are difficult. Practical application of mixin-based inheritance is illustrated in a sketch of an extension to Modula-3.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"425 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120929948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper describes a new approach to visualizing program systems within the object-oriented paradigm. This approach is based on a TEX-like notation which has been extended and generalized for specifying graphical layout of arbitrary objects. The CLOS meta-level architecture is used to associate visualization and application objects. We propose several useful techniques such as indirect values, slot and method demons, and instance-specific meta-objects. Our techniques require no modifications to the systems which are selected for visualization. We demonstrate the feasibility of our approach using application domains such as CLOS debugging and constraint systems.
{"title":"A framework for visualizing object-oriented systems","authors":"V. Haarslev, Ralf Möller","doi":"10.1145/97945.97974","DOIUrl":"https://doi.org/10.1145/97945.97974","url":null,"abstract":"This paper describes a new approach to visualizing program systems within the object-oriented paradigm. This approach is based on a TEX-like notation which has been extended and generalized for specifying graphical layout of arbitrary objects. The CLOS meta-level architecture is used to associate visualization and application objects. We propose several useful techniques such as indirect values, slot and method demons, and instance-specific meta-objects. Our techniques require no modifications to the systems which are selected for visualization. We demonstrate the feasibility of our approach using application domains such as CLOS debugging and constraint systems.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116915978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Chorus Object-Oriented Layer (COOL) is an extension of the facilities provided by the Chorus distributed operating system with additional functionality for the support of object-oriented environments. This functionality is realized by a layer built on top of the Chorus V3 Nucleus, which extends the Chorus interface with generic functions for object management: creation, deletion, storage, remote invocation and migration. One major goal of this approach was to explore the feasibility of general object management at the kernel level, with support of multiple object models at a higher level. We present the implementation of COOL and a first evaluation of this approach with a C++ environment using the COOL mechanisms.
{"title":"COOL: kernel support for object-oriented environments","authors":"S. Habert, V. Abrossimov","doi":"10.1145/97945.97978","DOIUrl":"https://doi.org/10.1145/97945.97978","url":null,"abstract":"The Chorus Object-Oriented Layer (COOL) is an extension of the facilities provided by the Chorus distributed operating system with additional functionality for the support of object-oriented environments. This functionality is realized by a layer built on top of the Chorus V3 Nucleus, which extends the Chorus interface with generic functions for object management: creation, deletion, storage, remote invocation and migration. One major goal of this approach was to explore the feasibility of general object management at the kernel level, with support of multiple object models at a higher level. We present the implementation of COOL and a first evaluation of this approach with a C++ environment using the COOL mechanisms.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131706112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We introduce a novel concurrent logic programming language, which we call LO, based on an extension of Horn logic. This language enhances the process view of objects implementable in Horn-based concurrent logic programming languages with powerful capabilities for knowledge structuring, leading to a flexible form of variable-structure inheritance. The main novelty about LO is a new kind of OR-concurrency which is dual to the usual AND-concurrency and provides us with the notion of structured process. Such OR-concurrency can be nicely characterized with a sociological metaphor as modelling the internal distribution of tasks inside a complex organization; this complements the external cooperation among different entities accounted for by AND-concurrency.
{"title":"LO and behold! Concurrent structured processes","authors":"J. Andreoli, R. Pareschi","doi":"10.1145/97945.97953","DOIUrl":"https://doi.org/10.1145/97945.97953","url":null,"abstract":"We introduce a novel concurrent logic programming language, which we call LO, based on an extension of Horn logic. This language enhances the process view of objects implementable in Horn-based concurrent logic programming languages with powerful capabilities for knowledge structuring, leading to a flexible form of variable-structure inheritance. The main novelty about LO is a new kind of OR-concurrency which is dual to the usual AND-concurrency and provides us with the notion of structured process. Such OR-concurrency can be nicely characterized with a sociological metaphor as modelling the internal distribution of tasks inside a complex organization; this complements the external cooperation among different entities accounted for by AND-concurrency.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123163959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We examine several problems related to the preservation of the Independence Principle inheritance. This principle states that all the characteristics of independent superclasses must be inherited by subclasses, even if there are name conflicts. In this context, a conventional approach is to use explicit class selection. We show that this mechanism suffers from serious limitations, and leads to inhibition of refinement and genericity. Our experimental object-oriented language ROME introduces the “Point of View” notion (using an “as-expressions” mechanism) which solves these problems.
{"title":"The point of view notion for multiple inheritance","authors":"B. Carré, J. Geib","doi":"10.1145/97945.97983","DOIUrl":"https://doi.org/10.1145/97945.97983","url":null,"abstract":"We examine several problems related to the preservation of the Independence Principle inheritance. This principle states that all the characteristics of independent superclasses must be inherited by subclasses, even if there are name conflicts. In this context, a conventional approach is to use explicit class selection. We show that this mechanism suffers from serious limitations, and leads to inhibition of refinement and genericity. Our experimental object-oriented language ROME introduces the “Point of View” notion (using an “as-expressions” mechanism) which solves these problems.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121204071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We present an iterative-design approach for reusable object-oriented software that augments existing design methods by incorporating iteration into the design methodology and focuses on the set of problems within the domain, encouraging reuse of existing design information. The model has five separate stages which are described, before an example design is outlined using the model with sample code constructs in C++. Our results have shown a high degree of code reuse when using the model, directly attributable to two distinct design stages. An analysis of these results is also presented.
{"title":"An iterative-design model for reusable object-oriented software","authors":"S. Gossain, B. Anderson","doi":"10.1145/97945.97949","DOIUrl":"https://doi.org/10.1145/97945.97949","url":null,"abstract":"We present an iterative-design approach for reusable object-oriented software that augments existing design methods by incorporating iteration into the design methodology and focuses on the set of problems within the domain, encouraging reuse of existing design information. The model has five separate stages which are described, before an example design is outlined using the model with sample code constructs in C++. Our results have shown a high degree of code reuse when using the model, directly attributable to two distinct design stages. An analysis of these results is also presented.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"79 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124600013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
While the contents of databases can be easily changed, their organization is typically extremely rigid. Some databases relax the rigidity of database organization somewhat by supporting simple changes to individual schemas. As described in this paper, OTGen supports not only more complex schema changes, but also database reorganization. A database administrator uses a declarative notation to describe mappings between objects created with old versions of schemas and their corresponding representations using new versions. OTGen generates a transformer that applies the mappings to update the database to the new definitions, thus facilitating improvements in performance, functionality, and usability of the database.1
{"title":"Beyond schema evolution to database reorganization","authors":"Barbara Staudt","doi":"10.1145/97945.97956","DOIUrl":"https://doi.org/10.1145/97945.97956","url":null,"abstract":"While the contents of databases can be easily changed, their organization is typically extremely rigid. Some databases relax the rigidity of database organization somewhat by supporting simple changes to individual schemas. As described in this paper, OTGen supports not only more complex schema changes, but also database reorganization. A database administrator uses a declarative notation to describe mappings between objects created with old versions of schemas and their corresponding representations using new versions. OTGen generates a transformer that applies the mappings to update the database to the new definitions, thus facilitating improvements in performance, functionality, and usability of the database.1","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129667639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The lecture given at the workshop was based on recent work published elsewhere [9, 10, 8, 7]. This abstract gives a brief description of the main results and ideas presented in that work, but does not provide any technical details; such details can be found in the papers mentioned above.
{"title":"Rewriting as a unified model of concurrency","authors":"J. Meseguer","doi":"10.1145/127056.127091","DOIUrl":"https://doi.org/10.1145/127056.127091","url":null,"abstract":"The lecture given at the workshop was based on recent work published elsewhere [9, 10, 8, 7]. This abstract gives a brief description of the main results and ideas presented in that work, but does not provide any technical details; such details can be found in the papers mentioned above.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"354 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123318574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Genericity allows the substitution of types in a class. This is usually obtained through parameterized classes, although they are inflexible since any class can be inherited but is not in itself parameterized. We suggest a new genericity mechanism, type substitution, which is a subclassing concept that complements inheritance: any class is generic, can be “instantiated” gradually without planning, and has all of its generic instances as subclasses.
{"title":"Type substitution for object-oriented programming","authors":"J. Palsberg, M. I. Schwartzbach","doi":"10.1145/97945.97965","DOIUrl":"https://doi.org/10.1145/97945.97965","url":null,"abstract":"Genericity allows the substitution of types in a class. This is usually obtained through parameterized classes, although they are inflexible since any class can be inherited but is not in itself parameterized. We suggest a new genericity mechanism, type substitution, which is a subclassing concept that complements inheritance: any class is generic, can be “instantiated” gradually without planning, and has all of its generic instances as subclasses.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"35 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123678114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper is concerned with the relation between subtyping and subclassing and their influence on programming language design. Traditionally subclassing as introduced by Simula has also been used for defining a hierarchical type system. The type system of a language can be characterized as strong or weak and the type checking mechanism as static or dynamic. Parameterized classes in combination with a hierarchical type-system is an example of a language construct that is known to create complicated type checking situations. In this paper these situations are analyzed and several different solutions are found. It is argued that an approach with a combination of static and dynamic type checking gives a reasonable balance also here. It is also concluded that this approach makes it possible to base the type system on the class/subclass mechanism.
{"title":"Strong typing of object-oriented languages revisited","authors":"O. Madsen, B. Magnusson, B. Møller-Pedersen","doi":"10.1145/97945.97964","DOIUrl":"https://doi.org/10.1145/97945.97964","url":null,"abstract":"This paper is concerned with the relation between <italic>subtyping</italic> and <italic>subclassing</italic> and their influence on programming language design. Traditionally subclassing as introduced by Simula has also been used for defining a hierarchical type system. The type system of a language can be characterized as <italic>strong</italic> or <italic>weak</italic> and the type checking mechanism as <italic>static</italic> or <italic>dynamic</italic>. Parameterized classes in combination with a hierarchical type-system is an example of a language construct that is known to create complicated type checking situations. In this paper these situations are analyzed and several different solutions are found. It is argued that an approach with a combination of static and dynamic type checking gives a reasonable balance also here. It is also concluded that this approach makes it possible to base the type system on the class/subclass mechanism.","PeriodicalId":135062,"journal":{"name":"OOPSLA/ECOOP '90","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1990-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117317059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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