Mixin-Based Programming in C++1
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MANNING Greenwich (74° W
Object Oriented Perl Object Oriented Perl DAMIAN CONWAY MANNING Greenwich (74° w. long.) For electronic browsing and ordering of this and other Manning books, visit http://www.manning.com. The publisher offers discounts on this book when ordered in quantity. For more information, please contact: Special Sales Department Manning Publications Co. 32 Lafayette Place Fax: (203) 661-9018 Greenwich, CT 06830 email: [email protected] ©2000 by Manning Publications Co. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by means electronic, mechanical, photocopying, or otherwise, without prior written permission of the publisher. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Where those designations appear in the book, and Manning Publications was aware of a trademark claim, the designations have been printed in initial caps or all caps. Recognizing the importance of preserving what has been written, it is Manning’s policy to have the books we publish printed on acid-free paper, and we exert our best efforts to that end. Library of Congress Cataloging-in-Publication Data Conway, Damian, 1964- Object oriented Perl / Damian Conway. p. cm. includes bibliographical references. ISBN 1-884777-79-1 (alk. paper) 1. Object-oriented programming (Computer science) 2. Perl (Computer program language) I. Title. QA76.64.C639 1999 005.13'3--dc21 99-27793 CIP Manning Publications Co. Copyeditor: Adrianne Harun 32 Lafayette -
A Comparative Study on the Effect of Multiple Inheritance Mechanism in Java, C++, and Python on Complexity and Reusability of Code
(IJACSA) International Journal of Advanced Computer Science and Applications, Vol. 8, No. 6, 2017 A Comparative Study on the Effect of Multiple Inheritance Mechanism in Java, C++, and Python on Complexity and Reusability of Code Fawzi Albalooshi Amjad Mahmood Department of Computer Science Department of Computer Science University of Bahrain University of Bahrain Kingdom of Bahrain Kingdom of Bahrain Abstract—Two of the fundamental uses of generalization in Booch, there are two problems associated with multiple object-oriented software development are the reusability of code inheritance and they are how to deal with name collisions from and better structuring of the description of objects. Multiple super classes, and how to handle repeated inheritance. He inheritance is one of the important features of object-oriented presents solutions to these two problems. Other researchers [4] methodologies which enables developers to combine concepts and suggest that there is a real need for multiple inheritance for increase the reusability of the resulting software. However, efficient object implementation. They justify their claim multiple inheritance is implemented differently in commonly referring to the lack of multiple subtyping in the ADA 95 used programming languages. In this paper, we use Chidamber revision which was considered as a deficiency that was and Kemerer (CK) metrics to study the complexity and rectified in the newer version [5]. It is clear that multiple reusability of multiple inheritance as implemented in Python, inheritance is a fundamental concept in object-orientation. The Java, and C++. The analysis of results suggests that out of the three languages investigated Python and C++ offer better ability to incorporate multiple inheritance in system design and reusability of software when using multiple inheritance, whereas implementation will better structure the description of objects Java has major deficiencies when implementing multiple modeling, their natural status and enabling further code reuse inheritance resulting in poor structure of objects. -
Mixins and Traits
◦ ◦◦◦ TECHNISCHE UNIVERSITAT¨ MUNCHEN¨ ◦◦◦◦ ◦ ◦ ◦◦◦ ◦◦◦◦ ¨ ¨ ◦ ◦◦ FAKULTAT FUR INFORMATIK Programming Languages Mixins and Traits Dr. Michael Petter Winter 2016/17 What advanced techiques are there besides multiple implementation inheritance? Outline Design Problems Cons of Implementation Inheritance 1 Inheritance vs Aggregation 1 2 (De-)Composition Problems Lack of finegrained Control 2 Inappropriate Hierarchies Inheritance in Detail A Focus on Traits 1 A Model for single inheritance 1 2 Inheritance Calculus with Separation of Composition and Inheritance Expressions Modeling 2 3 Modeling Mixins Trait Calculus Mixins in Languages Traits in Languages 1 (Virtual) Extension Methods 1 Simulating Mixins 2 Squeak 2 Native Mixins Reusability ≡ Inheritance? Codesharing in Object Oriented Systems is often inheritance-centric. Inheritance itself comes in different flavours: I single inheritance I multiple inheritance All flavours of inheritance tackle problems of decomposition and composition The Adventure Game Door ShortDoor LockedDoor canPass(Person p) canOpen(Person p) ? ShortLockedDoor canOpen(Person p) canPass(Person p) The Adventure Game Door <interface>Doorlike canPass(Person p) canOpen(Person p) Short canPass(Person p) Locked canOpen(Person p) ShortLockedDoor ! Aggregation & S.-Inheritance Door must explicitely provide canOpen(Person p) chaining canPass(Person p) Doorlike must anticipate wrappers ) Multiple Inheritance X The Wrapper FileStream SocketStream read() read() write() write() ? SynchRW acquireLock() releaseLock() ! Inappropriate Hierarchies -
Declaring Vars in Class Php
Declaring Vars In Class Php Is Tobe Esculapian or misformed after aluminous Neall plopping so magnanimously? Forrest corresponds prolixly? Forbidden Osmund sometimes pargets any lilliputian yell guardedly. How variable as int, php in using interpolation rather than configured one of people prefer to override whatever information useful whenever you call it leads to expose parts that We daily work with advertisers relevant to our readers. Acceptable in php programmers and retry saving again, declaration must be. Declaring a property but a class is an exact task use one table the keyword public protected or private followed by a normal variable declaration If. If you wrong there holding an IE bug with var a foo only declaring a global for file scope. Your class declaration format is declared protected field? You help also define methods in the class that allow tool to manipulate the values of object properties and perform operations on objects. PHP Class Properties Tutorials by Supun Kavinda. An amazon associate we declare the class in declarations as containers for our clients in the usages of a name given client exits and in? How clean and in declaring a class declaration scope in the vars of that are their parent selector. Using long array syntax array 1 2 3 for declaring arrays is generally. By declaring a class declaration, classes and see for? It turns out some interview situations, every time to magento source and other class names but you have a common occurrence, therefore considered a value. The var keyword in PHP is used to declare the property or variable of class which is primitive by default The var keyword is alike as out when declaring variables or root of a class Note The var keyword was deprecated from version 50. -
Interface Types for Haskell
Interface Types for Haskell Peter Thiemann and Stefan Wehr Institut f¨urInformatik, Universit¨atFreiburg, Germany {thiemann,wehr}@informatik.uni-freiburg.de Abstract. Interface types are a useful concept in object-oriented pro- gramming languages like Java or C#. A clean programming style advo- cates relying on interfaces without revealing their implementation. Haskell’s type classes provide a closely related facility for stating an in- terface separately from its implementation. However, there are situations in which no simple mechanism exists to hide the identity of the imple- mentation type of a type class. This work provides such a mechanism through the integration of lightweight interface types into Haskell. The extension is non-intrusive as no additional syntax is needed and no existing programs are affected. The implementation extends the treat- ment of higher-rank polymorphism in production Haskell compilers. 1 Introduction Interfaces in object-oriented programming languages and type classes in Haskell are closely related: both define the types of certain operations without revealing their implementations. In Java, the name of an interface also acts as an interface type, whereas the name of a type class can only be used to constrain types. Interface types are a proven tool for ensuring data abstraction and information hiding. In many cases, Haskell type classes can serve the same purpose, but there are situations for which the solutions available in Haskell have severe drawbacks. Interface types provide a simple and elegant solution in these situations. A modest extension to Haskell provides the simplicity and elegance of interface types: simply allow programmers to use the name of a type class as a first- class type. -
Chapter 8. Deploying an Osgi Service
Chapter 8. Deploying an OSGi Service The OSGi core framework defines the OSGi Service Layer, which provides a simple mechanism for bundles to interact by registering Java objects as services in the OSGi service registry. One of the strengths of the OSGi service model is that any Java object can be offered as a service: there are no particular constraints, inheritance rules, or annotations that must be applied to the service class. This chapter describes how to deploy an OSGi service using the OSGi blueprint container. The Blueprint Container ........................................................................................................... 92 Blueprint Configuration ................................................................................................... 93 Defining a Service Bean .................................................................................................. 95 Exporting a Service ........................................................................................................ 98 Importing a Service ...................................................................................................... 104 Publishing an OSGi Service .................................................................................................... 113 Accessing an OSGi Service ..................................................................................................... 118 FUSE ESB Deploying into the OSGi Container Version 4.2 91 Chapter 8. Deploying an OSGi Service The Blueprint Container Blueprint Configuration -
Learning Javascript Design Patterns
Learning JavaScript Design Patterns Addy Osmani Beijing • Cambridge • Farnham • Köln • Sebastopol • Tokyo Learning JavaScript Design Patterns by Addy Osmani Copyright © 2012 Addy Osmani. All rights reserved. Revision History for the : 2012-05-01 Early release revision 1 See http://oreilly.com/catalog/errata.csp?isbn=9781449331818 for release details. ISBN: 978-1-449-33181-8 1335906805 Table of Contents Preface ..................................................................... ix 1. Introduction ........................................................... 1 2. What is a Pattern? ...................................................... 3 We already use patterns everyday 4 3. 'Pattern'-ity Testing, Proto-Patterns & The Rule Of Three ...................... 7 4. The Structure Of A Design Pattern ......................................... 9 5. Writing Design Patterns ................................................. 11 6. Anti-Patterns ......................................................... 13 7. Categories Of Design Pattern ............................................ 15 Creational Design Patterns 15 Structural Design Patterns 16 Behavioral Design Patterns 16 8. Design Pattern Categorization ........................................... 17 A brief note on classes 17 9. JavaScript Design Patterns .............................................. 21 The Creational Pattern 22 The Constructor Pattern 23 Basic Constructors 23 Constructors With Prototypes 24 The Singleton Pattern 24 The Module Pattern 27 iii Modules 27 Object Literals 27 The Module Pattern -
Comp 411 Principles of Programming Languages Lecture 19 Semantics of OO Languages
Comp 411 Principles of Programming Languages Lecture 19 Semantics of OO Languages Corky Cartwright Mar 10-19, 2021 Overview I • In OO languages, OO data values (except for designated non-OO types) are special records [structures] (finite mappings from names to values). In OO parlance, the components of record are called members. • Some members of an object may be functions called methods. Methods take this (the object in question) as an implicit parameter. Some OO languages like Java also support static methods that do not depend on this; these methods have no implicit parameters. In efficient OO language implementations, method members are shared since they are the same for all instances of a class, but this sharing is an optimization in statically typed OO languages since the collection of methods in a class is immutable during program evaluation (computation). • A method (instance method in Java) can only be invoked on an object (the receiver, an implicit parameter). Additional parameters are optional, depending on whether the method expects them. This invocation process is called dynamic dispatch because the executed code is literally extracted from the object: the code invoked at a call site depends on the value of the receiver, which can change with each execution of the call. • A language with objects is OO if it supports dynamic dispatch (discussed in more detail in Overview II & III) and inheritance, an explicit taxonomy for classifying objects based on their members and class names where superclass/parent methods are inherited unless overridden. • In single inheritance, this taxonomy forms a tree; • In multiple inheritance, it forms a rooted DAG (directed acyclic graph) where the root class is the universal class (Object in Java). -
Interface Evolution Via Virtual Extension Methods Brian Goetz Fourth Draft, June 2011
Interface evolution via virtual extension methods Brian Goetz Fourth draft, June 2011 1. Problem statement Once published, it is impossible to add methods to an interface without breaking existing implementations. (Specifically, adding a method to an interface is not a source- compatible change.) The longer the time since a library has been published, the more likely it is that this restriction will cause grief for its maintainers. The addition of closures to the Java language in JDK 7 place additional stress on the aging Collection interfaces; one of the most significant benefits of closures is that it enables the development of more powerful libraries. It would be disappointing to add a language feature that enables better libraries while at the same time not extending the core libraries to take advantage of that feature1. V1 of the Lambda Strawman proposed C#-style static extension methods as a means of creating the illusion of adding methods to existing classes and interfaces, but they have significant limitations – for example, they cannot be overridden by classes that implement the interface being extended, so implementations are stuck with the “one size fits all” implementation provided as an extension2, and they are not reflectively discoverable. 2. Virtual extension methods3 In this document, we outline a mechanism for adding new methods to existing interfaces, which we call virtual extension methods. Existing interfaces can be augmented without compromising backward compatibility4 by adding extension methods to the interface, whose declaration would contain instructions for finding the default implementation in the event that implementers do not provide a method body. -
Dynamic Interfaces
Dynamic Interfaces Vasco T. Vasconcelos Simon J. Gay Antonio´ Ravara Departamento de Informatica´ Department of Computing Science SQIG at Instituto de Telecomunicac¸oes˜ Faculdade de Cienciasˆ da University of Glasgow, UK Department of Mathematics, IST, Universidade de Lisboa, Portugal [email protected] Technical University of Lisbon, Portugal [email protected] [email protected] Nils Gesbert Alexandre Z. Caldeira Department of Computing Science Departamento de Informatica´ University of Glasgow, UK Faculdade de Cienciasˆ da [email protected] Universidade de Lisboa, Portugal [email protected] Abstract 1. Introduction We define a small class-based object-oriented language in which Standard class-based object-oriented languages present the pro- the availability of methods depends on an object’s abstract state: grammer with the following view: an object is declared to belong to objects’ interfaces are dynamic. Each class has a session type which a certain type, and the type defines various methods; it is therefore provides a global specification of the availability of methods in possible at any time to call any of the methods described in the type. each state. A key feature is that the abstract state of an object However, there are often semantic reasons why it is not appropriate may depend on the result of a method whose return type is an to call a particular method when the object is in a particular inter- enumeration. Static typing guarantees that methods are only called nal state. For example: with a stack, one should not attempt to pop when they are available. -
Multiple Inheritance and the Resolution of Inheritance Conflicts
JOURNAL OF OBJECT TECHNOLOGY Online at http://www.jot.fm. Published by ETH Zurich, Chair of Software Engineering ©JOT, 2005 Vol. 4, No.2, March-April 2005 The Theory of Classification Part 17: Multiple Inheritance and the Resolution of Inheritance Conflicts Anthony J H Simons, Department of Computer Science, University of Sheffield, Regent Court, 211 Portobello Street, Sheffield S1 4DP, UK 1 INTRODUCTION This is the seventeenth article in a regular series on object-oriented theory for non- specialists. Using a second-order λ-calculus model, we have previously modelled the notion of inheritance as a short-hand mechanism for defining subclasses by extending superclass definitions. Initially, we considered the inheritance of type [1] and implementation [2] separately, but later combined both of these in a model of typed inheritance [3]. By simplifying the short-hand inheritance expressions, we showed how these are equivalent to canonical class definitions. We also showed how classes derived by inheritance are type compatible with their superclass. Further aspects of inheritance have included method combination [4], mixin inheritance [5] and inheritance among generic classes [6]. Most recently, we re-examined the ⊕ inheritance operator [7], to show how extending a class definition (the intension of a class) has the effect of restricting the set of objects that belong to the class (the extension of the class). We also added a type constraint to the ⊕ operator, to restrict the types of fields that may legally be combined with a base class to yield a subclass. By varying the form of this constraint, we modelled the typing of inheritance in Java, Eiffel, C++ and Smalltalk. -
Create Mixins with Interfaces and Extension Methods by Bill Wagner
Create Mixins with Interfaces and Extension Methods by Bill Wagner Mixins are small utility classes that define some useful functionality that will usually become part of something larger. For example, a class that implements a serial number to uniquely identify an object, or a timestamp that reports when an object was created. In C++, these mixin classes would be created using regular class definitions, and larger classes that wanted to use the mixin behavior would simply inherit from the mixin, in addition to any base classes it needed. Because the .NET Framework does not support multiple inheritance, we’ve typically used interface to define mixins. That works, but it’s not as powerful. One of the limitations of using interfaces to define mixin behavior is that every class that implements an interface must reimplement every method defined in that interface. That leads many developers to creating minimal interface definitions. (IEqualityComparer<T> has one method, IComparable<T> has only method). In those instances, the interface’s full functionality is completely defined in those small methods. But, what about cases where your interface can, or should, contain many more methods in order to support the developers that want to use the interface? That’s a perfect use case for extension methods. By creating extension methods using the interface, you can inject many more methods into the public definition of the interface, without forcing every developer to re-create those methods whenever he or she implements that interface. I’ve created a simple example based on strings that represent file paths. I often write classes that contain files or directories, usually for offline caches, or similar needs.