Design Patterns
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1 Design Pattern for Open Class (DRAFT) 2 Abstract Factory
1 Design Pattern for Open Class (DRAFT) Tanaka Akira <[email protected]> A design pattern describes a software architecture which is reusable and exten- sible. [GoF] is the book containing 23 design patterns for OOP languages like C++ and Java. [GoF] describes several trade offs of the patterns. In C++ and Java, a class is defined by only one module. However, there are languages which can define a class by two or more modules: Cecil, MultiJava, AspectJ, MixJuice, CLOS, Ruby, etc. Such class is called "open class" because it is extensible by modules implemented later [Chambers]. For languages with open class, more extensible and/or simpler design patterns exists. We studied design patterns with open class for each GoF design patterns. In this paper, we describe two patterns: the Abstract Factory pattern and the Visitor pattern. 2 Abstract Factory The Abstract Factory pattern is a design pattern for separating class names from the code which generates the object group of related classes for making them configurable. Following figure is the class diagram of the Abstract Factory pattern. Since the example described in [GoF] uses only one concrete factory for each binaries, the required concrete factory is selected statically. The example builds two binaries for Motif and Presentation Manager from a single source code. Two concrete factories are exist for Motif and Presentation Manager. When a binary is built, it is selected which concrete factory is linked. Such static selection can be implemented with the fewer number of classes by open class as following modules. • The module which defines Window and ScrollBar class and their methods which is independent to window systems. -
Design Case Study: Java Swing
Principles of Software Construction: Objects, Design, and Concurrency Part 2: Design case studies Design case study: Java Swing Charlie Garrod Chris Timperley 17-214 1 Administrivia • Reading due today: UML and Patterns 26.1 and 26.4 • Homework 4b due Thursday, October 17th https://commons.wikimedia.org/wiki/File:1_carcassonne_aerial_2016.jpg 17-214 2 Key concepts from Thursday • Observer design pattern • Introduction to concurrency – Not enough synchronization: safety failure – Too much synchronization: liveness failure • Event-based programming • Introduction to GUIs 17-214 3 GUI programming is inherently multi-threaded • Swing event dispatch thread (EDT) handles all GUI events – Mouse events, keyboard events, timer events, etc. • No other time-consuming activity allowed on the EDT – Violating this rule can cause liveness failures 17-214 4 Swing has many event listener interfaces • ActionListener • MouseListener • AdjustmentListener • TreeExpansionListener • FocusListener • TextListener • ItemListener • WindowListener • KeyListener • … class ActionEvent { int when; String actionCommand; int modifiers; Object source(); int id; … interface ActionListener { } void actionPerformed(ActionEvent e); } 17-214 5 Aside: lambdas vs. explicit class declarations? //static public void main… JFrame window = … JPanel panel = new JPanel(); window.setContentPane(panel); panel to hold the button JButton button = new JButton(“Click me”); button.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { System.out.println(“Button -
Tree Visitors in Clojure Update the Java Visitor Pattern with Functional Zippers
Tree visitors in Clojure Update the Java Visitor pattern with functional zippers Skill Level: Intermediate Alex Miller ([email protected]) Senior Engineer Revelytix 20 Sep 2011 JVM language explorer Alex Miller has recently discovered the benefits of implementing the Visitor pattern using Clojure, a functional Lisp variant for the Java Virtual Machine. In this article, he revisits the Visitor pattern, first demonstrating its use in traversing tree data in Java programs, then rewriting it with the addition of Clojure's functional zippers. I’ve used trees of domain objects in my Java applications for many years. More recently, I’ve been using them in Clojure. In each case, I've found that the Visitor pattern is a reliable tool for manipulating trees of data. But there are differences in how the pattern works in a functional versus object-oriented language, and in the results it yields. About Clojure Clojure is a dynamic and functional programming language variant of Lisp, written specifically for the JVM. Learn more about Clojure on developerWorks: •"The Clojure programming language" •"Clojure and concurrency" •"Solving the Expression Problem with Clojure 1.2" •"Using CouchDB with Clojure" In this article, I revisit domain trees and the Visitor pattern for the Java language, Tree visitors in Clojure Trademarks © Copyright IBM Corporation 2011 Page 1 of 27 developerWorks® ibm.com/developerWorks then walk through several visitor implementations using Clojure. Being a functional language, Clojure brings new tricks to data query and manipulation. In particular, I've found that integrating functional zippers into the Visitor pattern yields efficiency benefits, which I explore. -
Principles of Design
Principles of Design Balance Proportion/Scale Emphasis Rhythm Introduction The principles of design are essential to the development and production of clothing used by individuals and families around the world. Each principle has a specific role in creating an aesthetically pleasing garment or ensemble. The principles of design consist of: balance, proportion (also referred to as scale), emphasis, and rhythm. When a garment or ensemble uses the elements and principles of design to create a visual unity, harmony is achieved. Garments often integrate more than one principle, while drawing from the elements of design to create a cohesive look. The following discussion will present background information on each of the principles of design and applications to clothing design and construction. Balance According to Wolfe (2011) balance implies that there is an equilibrium or uniformity among the parts of a design (p. 205). To achieve balance, a garment or ensemble should have equal visual weight throughout the design. The use of structural features, added embellishments, or decorations to a garment contribute to the appearance of a garment or ensemble being balanced or not. A clothing designer can utilize surface designs on fabric to construct a garment creating visual balance. Further, color, line, and texture can impact the balance of a design. For example, cool and light colors have less visual weight than dark, warm colors. If an individual is wearing a small amount of a dark, warm color it can be balanced out with a larger amount of cool, light colors. Balance used in clothing design can be categorized into two groups: Formal and Informal Balance. -
APPLYING MODEL-VIEW-CONTROLLER (MVC) in DESIGN and DEVELOPMENT of INFORMATION SYSTEMS an Example of Smart Assistive Script Breakdown in an E-Business Application
APPLYING MODEL-VIEW-CONTROLLER (MVC) IN DESIGN AND DEVELOPMENT OF INFORMATION SYSTEMS An Example of Smart Assistive Script Breakdown in an e-Business Application Andreas Holzinger, Karl Heinz Struggl Institute of Information Systems and Computer Media (IICM), TU Graz, Graz, Austria Matjaž Debevc Faculty of Electrical Engineering and Computer Science, University of Maribor, Maribor, Slovenia Keywords: Information Systems, Software Design Patterns, Model-view-controller (MVC), Script Breakdown, Film Production. Abstract: Information systems are supporting professionals in all areas of e-Business. In this paper we concentrate on our experiences in the design and development of information systems for the use in film production processes. Professionals working in this area are neither computer experts, nor interested in spending much time for information systems. Consequently, to provide a useful, useable and enjoyable application the system must be extremely suited to the requirements and demands of those professionals. One of the most important tasks at the beginning of a film production is to break down the movie script into its elements and aspects, and create a solid estimate of production costs based on the resulting breakdown data. Several film production software applications provide interfaces to support this task. However, most attempts suffer from numerous usability deficiencies. As a result, many film producers still use script printouts and textmarkers to highlight script elements, and transfer the data manually into their film management software. This paper presents a novel approach for unobtrusive and efficient script breakdown using a new way of breaking down text into its relevant elements. We demonstrate how the implementation of this interface benefits from employing the Model-View-Controller (MVC) as underlying software design paradigm in terms of both software development confidence and user satisfaction. -
Facet: a Pattern for Dynamic Interfaces
Facet: A pattern for dynamic interfaces Author: Eric Crahen SUNY at Buffalo CSE Department Amherst, NY 14260 201 Bell Hall 716-645-3180 <[email protected]> Context: Wherever it is desirable to create a context sensitive interface in order to modify or control the apparent behavior if an object. Problem: How can I modify the behavior of an existing object so that different behaviors are shown under different circumstances; and yet still maintain a clean separation between the policy (when each behavior is available) and implementation of each behavior allowing them to be developed independently of one another? Forces: Interfaces provide an essential level of abstraction to object oriented programming. Generally, objects are able define aspects of their function very well using interfaces. At times, this may not be enough. When dealing with two or more classes whose responsibilities are distinctly separate, but whose behavior is closely related, classes can begin to resist modularization. For example, adding security to an application means inserting code that performs security checks into numerous locations in existing classes. Clearly, these responsibilities are distinct; the original classes being responsible for the tasks they were designed to perform, and the security classes being responsible for providing access control. However, making those original classes secure means intermingling code that deals with security. When the classes dealing with security are changed many classes are going to be impacted. One method of adding new behavior to an existing class might be to simply create a subclass and embed that new behavior. In the security example, this would mean creating a subclass for each class that needs to be secure and adding calls to the security code. -
Object-Oriented Desgin Visitor Pattern George Blankenship 1
Object-Oriented Desgin Visitor Pattern CSCI 253 Object Oriented Design: Visitor Pattern George Blankenship Visitor Pattern George Blankenship 1 Overview Creational Patterns Structural Patterns Behavioral Patterns Singleton Composite Chain of Respons. Abstract factory Façade Command Factory Method Proxy Interpreter Prototype Flyweight Iterator Builder Mediator Adapter Memento Bridge Observer Decorator State Strategy Template Method Visitor Pattern George Blankenship Visitor 2 The Elements of a Design Pattern • A pattern name • The problem that the pattern solves – Including conditions for the pattern to be applicable • The solution to the problem brought by the pattern – The elements (classes-objects) involved, their roles, responsibilities, relationships and collaborations – Not a particular concrete design or implementation • The consequences of applying the pattern – Time and space trade off – Language and implementation issues – Effects on flexibility, extensibility, portability Visitor Pattern George Blankenship 3 George Blankenship 1 Object-Oriented Desgin Visitor Pattern The Visitor Pattern: The Problem Represents an operation to be performed on the elements of an object structure. Visitor lets you define a new operation without changing the classes of the elements on which it operates • many distinct and unrelated operations need to be performed on objects in an object structure an you want to avoid “polluting” their classes with these operations • the classes defining the object structure rarely change but you often want to define new operations over the structure Visitor Pattern George Blankenship 4 Visitor Example • The root of the structure accepts a visitor: root.accept( visitor ) • The root and every child object in the structure have a an accept method: void accept( visitor ) { visitor.visit( this ); for each child of mine child.accept( visitor ) next } • In short order our visitor gets a visit() call from each object in the collection. -
Lecture 1 for Chapter 8, Object Design: Reusing Pattern Solutions
Object-Oriented Software Engineering Using UML, Patterns, and Java Chapter 8, Object Design: 8, Object Chapter Reuse and Patterns I and Patterns Reuse Object Design Object design is the process of adding details to the requirements analysis and making implementation decisions The object designer must choose among different ways to implement the analysis model with the goal to minimize execution time, memory and other measures of cost Requirements Analysis: Use cases, functional and dynamic model deliver operations for object model Object Design: Iterates on the models, in particular the object model and refine the models Object Design serves as the basis of implementation System Development as a Set of Activities System Problem Application objects Analysis Solution objects Design Custom objects - Object Design Off-the-Shelf Components - System Design Existing Machine Examples of Object Design Activities Identification of existing components Full definition of associations Full definition of classes (System Design => Service, Object Design => Subsystem interfaces/API) Choosing algorithms and data structures Identifying possibilities of reuse Detection of solution-domain classes Optimization Increase of inheritance Decision on control …… A More Detailed View of Object Design Activities Select Subsystem Specification Reuse Identifying missing Identifying components attributes & operations Specifying visibility Adjusting components Specifying types & signatures Identifying patterns Specifying constraints Specifying exceptions -
Pattern Languages in HCI: a Critical Review
HUMAN–COMPUTER INTERACTION, 2006, Volume 21, pp. 49–102 Copyright © 2006, Lawrence Erlbaum Associates, Inc. Pattern Languages in HCI: A Critical Review Andy Dearden Sheffield Hallam University Janet Finlay Leeds Metropolitan University ABSTRACT This article presents a critical review of patterns and pattern languages in hu- man–computer interaction (HCI). In recent years, patterns and pattern languages have received considerable attention in HCI for their potential as a means for de- veloping and communicating information and knowledge to support good de- sign. This review examines the background to patterns and pattern languages in HCI, and seeks to locate pattern languages in relation to other approaches to in- teraction design. The review explores four key issues: What is a pattern? What is a pattern language? How are patterns and pattern languages used? and How are values reflected in the pattern-based approach to design? Following on from the review, a future research agenda is proposed for patterns and pattern languages in HCI. Andy Dearden is an interaction designer with an interest in knowledge sharing and communication in software development. He is a senior lecturer in the Com- munication and Computing Research Centre at Sheffield Hallam University. Janet Finlay is a usability researcher with an interest in design communication and systems evaluation. She is Professor of Interactive Systems in Innovation North at Leeds Metropolitan University. 50 DEARDEN AND FINLAY CONTENTS 1. INTRODUCTION 2. THE SCOPE OF THIS REVIEW 2.1. General Software Design Patterns 2.2. Interface Software Design Patterns 2.3. Interaction Design Patterns 3. A SHORT HISTORY OF PATTERNS 3.1. -
GREATER GOLDEN HILL COMMUNITY PLAN UPDATE CHARRETTE 1 – Written Comments from Community Participants
GREATER GOLDEN HILL COMMUNITY PLAN UPDATE CHARRETTE 1 – Written Comments from Community Participants DRAFT October 9, 2010 Table 1 10 Things you Love about your Community - Golf course - open space - Dog park - Trails near the dog park canyon - Walkability - Eclectic architecture - Local businesses - Community-oriented events (Old House Fair, Walkabout, etc.) - Diversity - Natural views - Art spaces - The natural view - Connection to the park - Access/ proximity to downtown/ Balboa 10 Simple Improvements - Golf Course Open Space Add a walk path – make it safe all around the park Wildlife access Expand more family access to east end of park between Rec Center & 28th St. (use up some golf course space) - Improve connection to Balboa Park, improve street access & walkablility - Increase maintenance district funds for park? - Possible use of maintenance district funds for street repairs & lighting - Need a larger community center - 25th & F - idea for community center? - 25th & F – church for lease? - What to do for closed post office? - Bring the streetcar/ trolley to 30th & Fern - There are 2 auto shops near C & 25th - Underground the power lines - More street art - Enforce code on street signs and advertisements - Improve jogging & bike path around the golf course *All comments written herein are direct transcriptions of notes collected from each table as well as notes taken during the report back sessions of the workshop Golden Hill Charrette 1 – Comments - More walking trails - Improve sidewalks - lighting - More playgrounds - Rezone 25th street - Library/ Cultural Center/ Community Center - Need a Golden Hill sign (like Hillcrest or North Park) - Streetcar/Trolley Streets & Connections - Public art - Bus stops designed by a local artists competition - Community plazas and fountains - Entry signage for Golden Hill & South Park - Bike racks @ all destinations - Green Streets - Improve Russ Blvd. -
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. -
Design Pattern Implementation in Java and Aspectj
Design Pattern Implementation in Java and AspectJ Jan Hannemann Gregor Kiczales University of British Columbia University of British Columbia 201-2366 Main Mall 201-2366 Main Mall Vancouver B.C. V6T 1Z4 Vancouver B.C. V6T 1Z4 jan [at] cs.ubc.ca gregor [at] cs.ubc.ca ABSTRACT successor in the chain. The event handling mechanism crosscuts the Handlers. AspectJ implementations of the GoF design patterns show modularity improvements in 17 of 23 cases. These improvements When the GoF patterns were first identified, the sample are manifested in terms of better code locality, reusability, implementations were geared to the current state of the art in composability, and (un)pluggability. object-oriented languages. Other work [19, 22] has shown that implementation language affects pattern implementation, so it seems The degree of improvement in implementation modularity varies, natural to explore the effect of aspect-oriented programming with the greatest improvement coming when the pattern solution techniques [11] on the implementation of the GoF patterns. structure involves crosscutting of some form, including one object As an initial experiment we chose to develop and compare Java playing multiple roles, many objects playing one role, or an object [27] and AspectJ [25] implementations of the 23 GoF patterns. playing roles in multiple pattern instances. AspectJ is a seamless aspect-oriented extension to Java, which means that programming in AspectJ is effectively programming in Categories and Subject Descriptors Java plus aspects. D.2.11 [Software Engineering]: Software Architectures – By focusing on the GoF patterns, we are keeping the purpose, patterns, information hiding, and languages; D.3.3 intent, and applicability of 23 well-known patterns, and only allowing [Programming Languages]: Language Constructs and Features – the solution structure and solution implementation to change.