Introduction to Design Patterns
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
1. Domain Modeling
Software design pattern seminar sse, ustc Topic 8 Observer, Mediator, Facade Group K 1. The observer pattern (Behavioral pattern, chapter 16 and 17) 1) the observer is an interface or abstract class defining the operations to be used to update itself 2) a solution to these problems A. Decouple change and related responses so that such dependencies can be added or removed freely and dynamically 3) solution A. Observable defines the operations for attaching, de-attaching and notifying observers B. Observer defines the operations to update itself 4) liabilities A. Unwanted concurrent update to a concrete observable may occur Figure 1 Sample Observer Pattern 2. The mediator pattern (Behavioral pattern, chapter 16 and 17) 1) the mediator encapsulates how a set of objects interact and keeps objects from referring to each other explicitly 2) a solution to these problems A. a set of objects communicate in well-defined but complex ways. The resulting interdependencies are unstructured and difficult to understand B. reusing an object is difficult because it refers to and communicates with many other objects C. a behavior that's distributed between several classes should be customizable without a lot of subclassing 3) solution A. Mediator defines an interface for communicating with Colleague objects, knows the colleague classes and keep a reference to the colleague objects, and implements the communication and transfer the messages between the colleague classes 1 Software design pattern seminar sse, ustc B. Colleague classes keep a reference to its Mediator object, and communicates with the Mediator whenever it would have otherwise communicated with another Colleague 4) liabilities A. -
Designpatternsphp Documentation Release 1.0
DesignPatternsPHP Documentation Release 1.0 Dominik Liebler and contributors Jul 18, 2021 Contents 1 Patterns 3 1.1 Creational................................................3 1.1.1 Abstract Factory........................................3 1.1.2 Builder.............................................8 1.1.3 Factory Method......................................... 13 1.1.4 Pool............................................... 18 1.1.5 Prototype............................................ 21 1.1.6 Simple Factory......................................... 24 1.1.7 Singleton............................................ 26 1.1.8 Static Factory.......................................... 28 1.2 Structural................................................. 30 1.2.1 Adapter / Wrapper....................................... 31 1.2.2 Bridge.............................................. 35 1.2.3 Composite............................................ 39 1.2.4 Data Mapper.......................................... 42 1.2.5 Decorator............................................ 46 1.2.6 Dependency Injection...................................... 50 1.2.7 Facade.............................................. 53 1.2.8 Fluent Interface......................................... 56 1.2.9 Flyweight............................................ 59 1.2.10 Proxy.............................................. 62 1.2.11 Registry............................................. 66 1.3 Behavioral................................................ 69 1.3.1 Chain Of Responsibilities................................... -
Design Patterns in Ocaml
Design Patterns in OCaml Antonio Vicente [email protected] Earl Wagner [email protected] Abstract The GOF Design Patterns book is an important piece of any professional programmer's library. These patterns are generally considered to be an indication of good design and development practices. By giving an implementation of these patterns in OCaml we expected to better understand the importance of OCaml's advanced language features and provide other developers with an implementation of these familiar concepts in order to reduce the effort required to learn this language. As in the case of Smalltalk and Scheme+GLOS, OCaml's higher order features allows for simple elegant implementation of some of the patterns while others were much harder due to the OCaml's restrictive type system. 1 Contents 1 Background and Motivation 3 2 Results and Evaluation 3 3 Lessons Learned and Conclusions 4 4 Creational Patterns 5 4.1 Abstract Factory . 5 4.2 Builder . 6 4.3 Factory Method . 6 4.4 Prototype . 7 4.5 Singleton . 8 5 Structural Patterns 8 5.1 Adapter . 8 5.2 Bridge . 8 5.3 Composite . 8 5.4 Decorator . 9 5.5 Facade . 10 5.6 Flyweight . 10 5.7 Proxy . 10 6 Behavior Patterns 11 6.1 Chain of Responsibility . 11 6.2 Command . 12 6.3 Interpreter . 13 6.4 Iterator . 13 6.5 Mediator . 13 6.6 Memento . 13 6.7 Observer . 13 6.8 State . 14 6.9 Strategy . 15 6.10 Template Method . 15 6.11 Visitor . 15 7 References 18 2 1 Background and Motivation Throughout this course we have seen many examples of methodologies and tools that can be used to reduce the burden of working in a software project. -
The Power of Interoperability: Why Objects Are Inevitable
The Power of Interoperability: Why Objects Are Inevitable Jonathan Aldrich Carnegie Mellon University Pittsburgh, PA, USA [email protected] Abstract 1. Introduction Three years ago in this venue, Cook argued that in Object-oriented programming has been highly suc- their essence, objects are what Reynolds called proce- cessful in practice, and has arguably become the dom- dural data structures. His observation raises a natural inant programming paradigm for writing applications question: if procedural data structures are the essence software in industry. This success can be documented of objects, has this contributed to the empirical success in many ways. For example, of the top ten program- of objects, and if so, how? ming languages at the LangPop.com index, six are pri- This essay attempts to answer that question. After marily object-oriented, and an additional two (PHP reviewing Cook’s definition, I propose the term ser- and Perl) have object-oriented features.1 The equiva- vice abstractions to capture the essential nature of ob- lent numbers for the top ten languages in the TIOBE in- jects. This terminology emphasizes, following Kay, that dex are six and three.2 SourceForge’s most popular lan- objects are not primarily about representing and ma- guages are Java and C++;3 GitHub’s are JavaScript and nipulating data, but are more about providing ser- Ruby.4 Furthermore, objects’ influence is not limited vices in support of higher-level goals. Using examples to object-oriented languages; Cook [8] argues that Mi- taken from object-oriented frameworks, I illustrate the crosoft’s Component Object Model (COM), which has unique design leverage that service abstractions pro- a C language interface, is “one of the most pure object- vide: the ability to define abstractions that can be ex- oriented programming models yet defined.” Academ- tended, and whose extensions are interoperable in a ically, object-oriented programming is a primary focus first-class way. -
The Principles of Object-Oriented Javascript Zakas
TAKETAKE CONTROLCONTROL OFOF Foreword by Cody Lindley, Best-selling Author and Principal Frontend Architect JAVASCRIPT THE PRINCIPLES OF OBJECT-ORIENTED JAVASCRIPT JAVASCRIPT THE PRINCIPLES OF OBJECT-ORIENTED JAVASCRIPT THETHE PRINCIPLESPRINCIPLES OFOF OBJECTSOBJECTS at TandemSeven OBJECT-ORIENTEDOBJECT-ORIENTED If you’ve used a more traditional object-oriented • How to define your own constructors JAVASCRIPTJAVASCRIPT language, such as C++ or Java, JavaScript probably • How to work with and understand prototypes doesn’t seem object-oriented at all. It has no concept of classes, and you don’t even need to define any • Inheritance patterns for types and objects objects in order to write code. But don’t be fooled — The Principles of Object-Oriented JavaScript will leave NICHOLAS C. ZAKAS JavaScript is an incredibly powerful and expressive even experienced developers with a deeper understand- object-oriented language that puts many design ing of JavaScript. Unlock the secrets behind how objects decisions right into your hands. work in JavaScript so you can write clearer, more In The Principles of Object-Oriented JavaScript, flexible, and more efficient code. Nicholas C. Zakas thoroughly explores JavaScript’s object-oriented nature, revealing the language’s A B O U T T H E A U T H O R unique implementation of inheritance and other key characteristics. You’ll learn: Nicholas C. Zakas is a software engineer at Box and is known for writing on and speaking about the latest • The difference between primitive and reference in JavaScript best practices. He honed his experience values during his five years at Yahoo!, where he was principal • What makes JavaScript functions so unique frontend engineer for the Yahoo! home page. -
Evolution and Composition of Object-Oriented Frameworks
Evolution and Composition of Object-Oriented Frameworks Michael Mattsson University of Karlskrona/Ronneby Department of Software Engineering and Computer Science ISBN 91-628-3856-3 © Michael Mattsson, 2000 Cover background: Digital imagery® copyright 1999 PhotoDisc, Inc. Printed in Sweden Kaserntryckeriet AB Karlskrona, 2000 To Nisse, my father-in-law - who never had the opportunity to study as much as he would have liked to This thesis is submitted to the Faculty of Technology, University of Karlskrona/Ronneby, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering. Contact Information: Michael Mattsson Department of Software Engineering and Computer Science University of Karlskrona/Ronneby Soft Center SE-372 25 RONNEBY SWEDEN Tel.: +46 457 38 50 00 Fax.: +46 457 27 125 Email: [email protected] URL: http://www.ipd.hk-r.se/rise Abstract This thesis comprises studies of evolution and composition of object-oriented frameworks, a certain kind of reusable asset. An object-oriented framework is a set of classes that embodies an abstract design for solutions to a family of related prob- lems. The work presented is based on and has its origin in industrial contexts where object-oriented frameworks have been developed, used, evolved and managed. Thus, the results are based on empirical observations. Both qualitative and quanti- tative approaches have been used in the studies performed which cover both tech- nical and managerial aspects of object-oriented framework technology. Historically, object-oriented frameworks are large monolithic assets which require several design iterations and are therefore costly to develop. With the requirement of building larger applications, software engineers have started to compose multiple frameworks, thereby encountering a number of problems. -
Secure Telemedicine System for Home Health Care
Graduate Theses, Dissertations, and Problem Reports 2000 Secure telemedicine system for home health care Sridhar Vasudevan West Virginia University Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Vasudevan, Sridhar, "Secure telemedicine system for home health care" (2000). Graduate Theses, Dissertations, and Problem Reports. 1099. https://researchrepository.wvu.edu/etd/1099 This Thesis is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. SECURE TELEMEDICINE SYSTEM FOR HOME HEALTH CARE Sridhar Vasudevan Thesis submitted to the College of Engineering and Mineral Resources at West Virginia University in partial fulfillment of the requirements for the degree of Master of Science in Computer Science V.Jagannathan, Ph.D., Chair Sumitra Reddy, Ph.D. James D. Mooney, Ph.D. Department of Computer Science and Electrical Engineering Morgantown, West Virginia 2000 Keywords: EJB, Java, Home Health Care, Telemedicine SECURE TELEMEDICINE SYSTEM FOR HOME HEALTH CARE Sridhar Vasudevan ABSTRACT This thesis describes a low-cost telemedicine system that provides home based patient care by linking patients with skilled nurses at the home care agency. -
Java Design Patterns I
Java Design Patterns i Java Design Patterns Java Design Patterns ii Contents 1 Introduction to Design Patterns 1 1.1 Introduction......................................................1 1.2 What are Design Patterns...............................................1 1.3 Why use them.....................................................2 1.4 How to select and use one...............................................2 1.5 Categorization of patterns...............................................3 1.5.1 Creational patterns..............................................3 1.5.2 Structural patterns..............................................3 1.5.3 Behavior patterns...............................................3 2 Adapter Design Pattern 5 2.1 Adapter Pattern....................................................5 2.2 An Adapter to rescue.................................................6 2.3 Solution to the problem................................................7 2.4 Class Adapter..................................................... 11 2.5 When to use Adapter Pattern............................................. 12 2.6 Download the Source Code.............................................. 12 3 Facade Design Pattern 13 3.1 Introduction...................................................... 13 3.2 What is the Facade Pattern.............................................. 13 3.3 Solution to the problem................................................ 14 3.4 Use of the Facade Pattern............................................... 16 3.5 Download the Source Code............................................. -
Obstacl: a Language with Objects, Subtyping, and Classes
OBSTACL: A LANGUAGE WITH OBJECTS, SUBTYPING, AND CLASSES A DISSERTATION SUBMITTED TO THE DEPARTMENT OF COMPUTER SCIENCE AND THE COMMITTEE ON GRADUATE STUDIES OF STANFORD UNIVERSITY IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY By Amit Jayant Patel December 2001 c Copyright 2002 by Amit Jayant Patel All Rights Reserved ii I certify that I have read this dissertation and that in my opin- ion it is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. John Mitchell (Principal Adviser) I certify that I have read this dissertation and that in my opin- ion it is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. Kathleen Fisher I certify that I have read this dissertation and that in my opin- ion it is fully adequate, in scope and quality, as a dissertation for the degree of Doctor of Philosophy. David Dill Approved for the University Committee on Graduate Studies: iii Abstract Widely used object-oriented programming languages such as C++ and Java support soft- ware engineering practices but do not have a clean theoretical foundation. On the other hand, most research languages with well-developed foundations are not designed to support software engineering practices. This thesis bridges the gap by presenting OBSTACL, an object-oriented extension of ML with a sound theoretical basis and features that lend themselves to efficient implementation. OBSTACL supports modular programming techniques with objects, classes, structural subtyping, and a modular object construction system. OBSTACL's parameterized inheritance mechanism can be used to express both single inheritance and most common uses of multiple inheritance. -
Approaches to Composition and Refinement in Object-Oriented Design
Approaches to Composition and Refinement in Object-Oriented Design Marcel Weiher Matrikelnummer 127367 Diplomarbeit Fachbereich Informatik Technische Unversitat¨ Berlin Advisor: Professor Bernd Mahr August 21, 1997 Contents 1 Introduction 4 1.1 Object Orientation 4 1.2 Composition and Refinement 5 2 State of the Art 7 2.1 Frameworks 7 2.1.1 Framework Construction 8 2.1.2 Reusing Frameworks 9 2.2 Design Patterns 10 2.2.1 Reusing Patterns 10 2.2.2 Communicating Patterns 12 2.3 Commentary 13 3 Enhanced Interfaces 14 3.1 Interface Typing 14 3.2 The Refinement Interface 15 3.2.1 Protocol Dependencies 15 3.2.2 Reuse Contracts 18 3.3 Interaction Interfaces 21 3.3.1 Interaction Protocols 21 3.3.2 Protocol Specification and Matching 22 3.4 Commentary 23 4 Orthogonalization 24 4.1 Delegation 24 4.1.1 Prototypes Languages 25 4.1.2 Composition Filters 25 4.2 Mixins 27 4.2.1 Mixins and Multiple Inheritance 28 4.2.2 Nested Dynamic Mixins 28 4.3 Extension Hierarchies 29 4.3.1 Extension Operators 29 4.3.2 Conflicts: Detection, Resolution, Avoidance 30 4.4 Canonic Components 31 4.4.1 Components 31 4.4.2 Views 32 4.5 Commentary 33 1 5 Software Architecture 34 5.1 Architectural Styles 34 5.1.1 Pipes and Filters 35 5.1.2 Call and Return 36 5.1.3 Implicit Invocation 36 5.1.4 Using Styles 37 5.2 Architecture Description Languages 38 5.2.1 UniCon 38 5.2.2 RAPIDE 39 5.2.3 Wright 40 5.2.4 ACME 43 5.3 Commentary 43 6 Non-linear Refinement 45 6.1 Domain Specific Software Generators 45 6.1.1 A Domain Independent Model 46 6.1.2 Implementation 47 6.2 Subject Oriented -
Design Patterns Mock Test
DDEESSIIGGNN PPAATTTTEERRNNSS MMOOCCKK TTEESSTT http://www.tutorialspoint.com Copyright © tutorialspoint.com This section presents you various set of Mock Tests related to Design Patterns Framework. You can download these sample mock tests at your local machine and solve offline at your convenience. Every mock test is supplied with a mock test key to let you verify the final score and grade yourself. DDEESSIIGGNN PPAATTTTEERRNNSS MMOOCCKK TTEESSTT IIII Q 1 - Which of the following describes the Composite pattern correctly? A - This pattern builds a complex object using simple objects and using a step by step approach. B - This pattern is used where we need to treat a group of objects in similar way as a single object. C - This pattern hides the complexities of the system and provides an interface to the client using which the client can access the system. D - This pattern is primarily used to reduce the number of objects created and to decrease memory footprint and increase performance. Q 2 - Which of the following describes the Decorator pattern correctly? A - This pattern allows a user to add new functionality to an existing object without altering its structure. B - This pattern is used where we need to treat a group of objects in similar way as a single object. C - This pattern hides the complexities of the system and provides an interface to the client using which the client can access the system. D - This pattern is primarily used to reduce the number of objects created and to decrease memory footprint and increase performance. Q 3 - Which of the following describes the Facade pattern correctly? A - This pattern allows a user to add new functionality to an existing object without altering its structure. -
Object Oriented Languages
Object oriented languages dr inż. Marcin Pietroń Object oriented programming • Object languages: - Java (business applications, mobile software etc.) - C++ (embedded, real-time, finance- sector) - Python (prototyping, testing) - Smalltalk - Ruby (web) - Objective-C (mobile) - … Object oriented programming • programming paradigm - data structures called "objects", contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. Object oriented programming • a feature of objects is that an object's procedures can access and often modify the data fields of the object with which they are associated, • in OO programming, objects in a software system interact with one another. Object oriented programming • There is significant diversity in object-oriented programming, but most popular languages are class-based, meaning that objects are instances of classes, which typically also determines their type. Object oriented programming Languages that support object-oriented programming use inheritance for code reuse and extensibility in the form of either classes or prototypes. Those that use classes support two main concepts: • Objects - structures that contain both data and procedures • Classes - definitions for the data format and available procedures for a given type or class of object; may also contain data and procedures (class methods) Object oriented programming • Objects sometimes correspond to things found in the real world (e.g. a graphics program may have objects such as „figure ", "circle ", "square" or " cursor ", online shop may have objects such as "shopping cart" "customer" " basket " or "product ", • Objects can represent more abstract things and entities, like an object that represents an open file, or an object which provides some service (e.g.