Results 1 - 10
of
172
Object-oriented Analysis and Design with Applications
- 2ND EDITION, THE BENJAMIN/CUMMINGS PUBLISHING COMPANY, INC
, 1994
"... ..."
(Show Context)
Dynamic Typing in a Statically Typed Language
"... Statically typed programming languages allow earlier error checking, better enforcement of disciplined programming styles, and generation of more e cient object code than languages where all type consistency checks are performed at run time. However, even in statically typed languages, there is ofte ..."
Abstract
-
Cited by 171 (4 self)
- Add to MetaCart
Statically typed programming languages allow earlier error checking, better enforcement of disciplined programming styles, and generation of more e cient object code than languages where all type consistency checks are performed at run time. However, even in statically typed languages, there is often the need to deal with data whose type cannot be determined at compile time. To handle such situations safely, we propose to add a type Dynamic whose values are pairs of a value v andatype tag T where v has the type denoted by T. Instances of Dynamic are built with an explicit tagging construct and inspected with a type safe typecase construct. This paper explores the syntax, operational semantics, and denotational semantics of a simple language including the type Dynamic. Wegive examples of how dynamically typed values can be used in programming. Then we discuss an operational semantics for our language and obtain a soundness theorem. We present two formulations of the denotational semantics of this language and relate them to the operational semantics. Finally,we consider the implications of polymorphism and some implementation issues.
Working with Persistent Objects: To Swizzle or Not to Swizzle
, 1991
"... Pointer swizzling is the conversion of database objects between an external form (object identifiers) and an internal form (direct memory pointers). Swizzling is used in some object-oriented databases, persistent object stores, and persistent and database programming language implementations to sp ..."
Abstract
-
Cited by 127 (5 self)
- Add to MetaCart
Pointer swizzling is the conversion of database objects between an external form (object identifiers) and an internal form (direct memory pointers). Swizzling is used in some object-oriented databases, persistent object stores, and persistent and database programming language implementations to speed manipulation of memory resident data. Here we describe a simplifying model of application behavior, revealing those aspects where swizzling is most relevant in both benefits and costs. The model has a number of parameters, whichwehavemeasured for a particular instance of the Mneme persistent object store, varying the swizzling technique used. The results confirm most of the intuitive, qualitative tradeoffs, with the quantitative data showing that some performance differences between schemes are smaller than might be expected. However, there are some interesting effects that run counter to naive intuition, most of which we explain using deeper analysis of the algorithms and data struc...
Database programming in Machiavelli, a polymorphic language with static type inference
, 1989
"... Machiavelli is a polymorphically typed programming language in the spirit of ML, but supports an extended method of type inferencing that makes its polymorphism more general and appropriate for database applications. In particular, a function that selects a field f of a records is polymorphic in the ..."
Abstract
-
Cited by 90 (20 self)
- Add to MetaCart
(Show Context)
Machiavelli is a polymorphically typed programming language in the spirit of ML, but supports an extended method of type inferencing that makes its polymorphism more general and appropriate for database applications. In particular, a function that selects a field f of a records is polymorphic in the sense that it can be applied to any record which contains a field f with the appropriate type. When combined with a set data type and database operations including join and projection, this provides a natural medium for relational database programming. Moreover, by implementing database objects as reference types and generating the appropriate views — sets of structures with “identity ” — we can achieve a degree of static type checking for object-oriented databases. 1
ODE (Object Database and Environment): The Language and the Data Model
- Proc. ACM-SIGMOD 1989 Int'l Conf. Management of Data
, 1989
"... ODE is a database system and environment based on the object paradigm. It offers one integrated data model for both database and general purpose manipulation. The database is defined, queried and manipulated in the database programming language O++ which is based on C++. O++ borrows and extends the ..."
Abstract
-
Cited by 88 (12 self)
- Add to MetaCart
ODE is a database system and environment based on the object paradigm. It offers one integrated data model for both database and general purpose manipulation. The database is defined, queried and manipulated in the database programming language O++ which is based on C++. O++ borrows and extends the object definition facility of C++, called the class. Classes support data encapsulation and multiple inheritance. We provide facilities for creating persistent and versioned objects, defining sets, and iterating over sets and clusters of persistent objects. We also provide facilities to associate constraints and triggers with objects. This paper presents the linguistic facilities provided in O++ and the data model it supports. 1. INTRODUCTION The object paradigm is a natural way of organizing data as it allows users to structure, retrieve and update data in terms of the application domain. ODE is a database system and environment based on the object paradigm. The database is defined, queri...
The EXODUS Extensible DBMS Project: An Overview
- Readings in Object-Oriented Database Systems
, 1990
"... This paper presents an overview of EXODUS, an extensible database system project that is addressing data management problems posed by a variety of challenging new applications. The goal of the project is to facilitate the fast development of high-performance, application-specific database systems. E ..."
Abstract
-
Cited by 83 (2 self)
- Add to MetaCart
(Show Context)
This paper presents an overview of EXODUS, an extensible database system project that is addressing data management problems posed by a variety of challenging new applications. The goal of the project is to facilitate the fast development of high-performance, application-specific database systems. EXODUS provides certain kernel facilities, including a versatile storage manager. In addition, it provides an architectural framework for building application-specific database systems; powerful tools to help automate the generation of such systems, including a rule-based query optimizer generator and a persistent programming language; and libraries of generic software components (e.g., access methods) that are likely to be useful for many application domains. We briefly describe each of the components of EXODUS in this paper, and we also describe a next-generation DBMS that we are now building using the EXODUS tools. 1.
Comprehensions, a Query Notation for DBPLs
- Proceedings of the 3rd International Workshop on Database Programming Languages
, 1991
"... This paper argues that comprehensions, a construct found in some programming languages, are a good query notation for DBPLs. It is shown that, like many other query notations, comprehensions can be smoothly integrated into DBPLs and allow queries to be expressed clearly, concisely and efficiently. M ..."
Abstract
-
Cited by 63 (4 self)
- Add to MetaCart
This paper argues that comprehensions, a construct found in some programming languages, are a good query notation for DBPLs. It is shown that, like many other query notations, comprehensions can be smoothly integrated into DBPLs and allow queries to be expressed clearly, concisely and efficiently. More significantly, two advantages of comprehensions are demonstrated. The first advantage is that, unlike conventional notations, comprehension queries combine computational power with ease of optimisation. That is, not only can comprehension queries express both recursion and computation, but equivalent comprehension transformations exist for all of the major conventional optimisations. The second advantage is that comprehensions provide a uniform notation for expressing and performing some optimisation on queries over several bulk data types. The bulk types that comprehensions can be defined over include sets, relations, bags and lists. A DBPL can also be automatically extended to provide and partially optimise comprehension queries over new bulk types constructed by the application programmer, providing that the new type has some well-defined properties. 1
The Design of the E Programming Language
- ACM Transactions on Programming Languages and Systems
, 1993
"... E is an extension of C++ designed for writing software systems to support persistent applications. Originally designed as a language for implementing database systems, E has evolved into a general persistent programming language E was the first C++ extension to support transparent persistence, the f ..."
Abstract
-
Cited by 62 (3 self)
- Add to MetaCart
(Show Context)
E is an extension of C++ designed for writing software systems to support persistent applications. Originally designed as a language for implementing database systems, E has evolved into a general persistent programming language E was the first C++ extension to support transparent persistence, the first C++ implementation to support generic classes, and remains the only C++ extension to provide general-purpose lterators, In addition to its contributions to the C + + programming domain, work on E has made several contributions to the field of persmtent languages in general, including several distinct implementations of persistence. Thm paper describes the main features of E and shows through examples how E addresses many of the problems that arise in building persistent systems.
Towards A Deductive Object-Oriented Database Language
- Data & Knowledge Engineering
, 1990
"... A language for databases with sets, tuples, lists, object identity and structural inheritance is proposed. The core language is logic-based with a fixpoint semantics. Methods with overloading and methods evaluated externally providing extensibility of the language are considered. Other important iss ..."
Abstract
-
Cited by 59 (0 self)
- Add to MetaCart
(Show Context)
A language for databases with sets, tuples, lists, object identity and structural inheritance is proposed. The core language is logic-based with a fixpoint semantics. Methods with overloading and methods evaluated externally providing extensibility of the language are considered. Other important issues such as updates and the introduction of explicit control are discussed. 1 INTRODUCTION The success of the relational database model [19, 38, 27] is certainly due to technological advances such as fast query processing or reliable concurrency control. However, we believe that a major factor in that success has been the existence of simple-to-use languages allowing the definition and manipulation of data. This has to be remembered while considering future generations of database systems. Object-oriented database systems are now being developed, e.g., [15, 12, 22, 39, 36]. An object-oriented approach [24] is used to answer the needs of a much wider variety of applications. Most of th...
A compilation method for ML-style polymorphic record calculi
, 1992
"... Polymorphic record calculi have recently attracted much attention as a typed foundation for objectoriented programming. This is based on the fact that a function that selects a field l of a record can be given a polymorphic type that enables it to be applied to various records containing a field l. ..."
Abstract
-
Cited by 57 (8 self)
- Add to MetaCart
(Show Context)
Polymorphic record calculi have recently attracted much attention as a typed foundation for objectoriented programming. This is based on the fact that a function that selects a field l of a record can be given a polymorphic type that enables it to be applied to various records containing a field l. Recent studies have established techniques to develop an ML-style type inference algorithm for such a polymorphic type system. There seems to be, however, no established method to compile an ML-style polymorphic record calculus into efficient code. The purpose of this paper is to present one such method. We define a polymorphic record calculus as an extension of Damas and Milner’s proof system for ML. For this calculus, we define an implementation calculus where records are represented as arrays of (references to) values and field selection is performed by direct indexing. To represent polymorphic field selection, the implementation calculus contains an abstraction mechanism over indexes. We then develop an algorithm to translate the polymorphic record calculus into the implementation calculus by refining a type inference algorithm; it simultaneously computes a principal type scheme in the polymorphic record calculus and a correct implementation term in the implementation calculus. The type inference is shown to be sound and complete in the sense of Damas-Milner’s algorithm for ML. Moreover, the polymorphic type system is shown to be sound with respect to an operational semantics of the translated terms in the implementation calculus.
