Patterns of Patterns Csci 4448/5448: Object-Oriented Analysis & Design Lecture 26 — 04/14/2011
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One-Slide Summary Lecture Outline
Using Design Patterns #1 One-Slide Summary • Design patterns are solutions to recurring OOP design problems. There are patterns for constructing objects, structuring data, and object behavior . • Since this is PL, we’ll examine how language features like (multiple) inheritance and dynamic dispatch relate to design patterns. #2 Lecture Outline • Design Patterns • Iterator • Observer • Singleton • Mediator #3 1 What is a design pattern? • A solution for a recurring problem in a large object-oriented programming system – Based on Erich Gamma’s Ph.D. thesis, as presented in the “gang of four” book • “Each pattern describes a problem which occurs over and over again in our environment, and then describes the core of the solution to that problem, in such a way that you can use this solution a million times over, without ever doing it the same way twice” – Charles Alexander #4 Types of design patterns • Design patterns can be (roughly) grouped into three categories: • Creational patterns – Constructing objects • Structural patterns – Controlling the structure of a class, e.g. affecting the API or the data structure layout • Behavioral patterns – Deal with how the object behaves #5 Iterator design pattern • Often you may have to move through a collection – Tree (splay, AVL, binary, red-black, etc.), linked list, array, hash table, dictionary, etc. • Easy for arrays and vectors • But hard for more complicated data structures – Hash table, dictionary, etc. • The code doing the iteration should not have to know the details of the data structure -
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 -
Object-Oriented Analysis, Design and Implementation
Undergraduate Topics in Computer Science Brahma Dathan Sarnath Ramnath Object-Oriented Analysis, Design and Implementation An Integrated Approach Second Edition Undergraduate Topics in Computer Science Undergraduate Topics in Computer Science (UTiCS) delivers high-quality instruc- tional content for undergraduates studying in all areas of computing and information science. From core foundational and theoretical material to final-year topics and applications, UTiCS books take a fresh, concise, and modern approach and are ideal for self-study or for a one- or two-semester course. The texts are all authored by established experts in their fields, reviewed by an international advisory board, and contain numerous examples and problems. Many include fully worked solutions. More information about this series at http://www.springer.com/series/7592 Brahma Dathan • Sarnath Ramnath Object-Oriented Analysis, Design and Implementation An Integrated Approach Second Edition 123 Brahma Dathan Sarnath Ramnath Department of Information and Computer Department of Computer Science Science and Information Technology Metropolitan State University St. Cloud State University St. Paul, MN St. Cloud, MN USA USA Series editor Ian Mackie Advisory Board Samson Abramsky, University of Oxford, Oxford, UK Karin Breitman, Pontifical Catholic University of Rio de Janeiro, Rio de Janeiro, Brazil Chris Hankin, Imperial College London, London, UK Dexter Kozen, Cornell University, Ithaca, USA Andrew Pitts, University of Cambridge, Cambridge, UK Hanne Riis Nielson, Technical University of Denmark, Kongens Lyngby, Denmark Steven Skiena, Stony Brook University, Stony Brook, USA Iain Stewart, University of Durham, Durham, UK A co-publication with the Universities Press (India) Private Ltd., licensed for sale in all countries outside of India, Pakistan, Bhutan, Bangladesh, Sri Lanka, Nepal, The Maldives, Middle East, Malaysia, Indonesia and Singapore. -
Design Patterns Design Patterns
Design Patterns CSC207 – Software Design Design Patterns • Design pattern: – A general description of the solution to a well- established problem using an arrangement of classes and objects. • Patterns describe the shape of code rather than the details. – There are lots of them in CSC 301 and 302. Loop patterns from first year • Loop pattern: – A general description of an algorithm for processing items in a collection. • All of you (hopefully) have some loop patterns in your heads. • You don’t really need to think about these any more; you just use them, and you should be able to discuss them with your fellow students. • Some first-year patterns: – Process List – Counted Loop – Accumulator – Sentinel Process list pattern • Purpose: to process every item in a collection where you don’t care about order or context; you don’t need to remember previous items. • Outline: • Example: • Other example: darken every pixel in a picture Counted loop pattern • Purpose: to process a range of indices in a collection. • Outline: • Example: • Other example: print indices of even-length string Accumulator pattern • Purpose: to accumulate information about items in a collection. • Outline: • Example: • Other examples: sum, min, accumulate a list of items meeting a particular criterion. Sentinel pattern • Purpose: to remove a condition in a loop guard. • Outline: • Example: Sentinel pattern, continued • Here is the code that Sentinal replaces; note that i != list.size() is evaluated every time through the loop, even though it is false only once. Design Pattern -
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 -
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. -
Singleton ● Iterator
CSC207 Week 6 Larry Zhang 1 Logistics ● Midterm: next Friday (October 27), 5:10 PM - 7:00 PM ● 110 minutes ● No aid ● Room: TBA (Note it’s not the lecture room) ● Past tests posted on the course website: http://axiom.utm.utoronto.ca/~207/17f/tests.shtml ● Arnold will send emails with more info. 2 Design Patterns 3 /r/LifeProTips 4 Design Patterns Design patterns are like “LifeProTips” for software design. ● Effective use of the OO Paradigm. ● Using the patterns results in flexible, malleable, maintainable code. ● It usually allows plug and play additions to existing code. ● It gives developers a vocabulary to talk about recurring class organizations. 5 Design Patterns for Today ● Observer ● Singleton ● Iterator 6 The Observer Pattern 7 Goals ● When certain objects need to be informed about the changes occurred in other objects. ● One object changes state, all its dependents are notified and updated automatically. ● Programmer only need to worry about how the observer changes if the observables changes, and connecting the observers and observables. ● Real-life example: setting up Pre-Authorized Bill Payment 8 General Implementation 9 Java Implementation 10 DEMO #1 Implement Our Own Observer/Observable observer/Observable.java observer/Observer.java 11 DEMO #2 Use Our Observer/Observable observer/LightBulb.java observer/LightBulbObserver.java observer/LightBulbObservable.java observer/LightBulbMain.java 12 Advanced Issues in Observer Pattern Push and Pull communication methods ● Push model: the Observable send all information about the change -
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. -
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............................................. -
Mutable Class Design Pattern Nikolay Malitsky Nova Southeastern University, [email protected]
Nova Southeastern University NSUWorks CEC Theses and Dissertations College of Engineering and Computing 2016 Mutable Class Design Pattern Nikolay Malitsky Nova Southeastern University, [email protected] This document is a product of extensive research conducted at the Nova Southeastern University College of Engineering and Computing. For more information on research and degree programs at the NSU College of Engineering and Computing, please click here. Follow this and additional works at: https://nsuworks.nova.edu/gscis_etd Part of the Other Computer Sciences Commons, and the Theory and Algorithms Commons Share Feedback About This Item NSUWorks Citation Nikolay Malitsky. 2016. Mutable Class Design Pattern. Doctoral dissertation. Nova Southeastern University. Retrieved from NSUWorks, College of Engineering and Computing. (956) https://nsuworks.nova.edu/gscis_etd/956. This Dissertation is brought to you by the College of Engineering and Computing at NSUWorks. It has been accepted for inclusion in CEC Theses and Dissertations by an authorized administrator of NSUWorks. For more information, please contact [email protected]. Mutable Class Design Pattern by Nikolay Malitsky A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computer Science Graduate School of Computer and Information Sciences Nova Southeastern University 2016 We hereby certify that this dissertation, submitted by Nikolay Malitsky, conforms to acceptable standards and is fully adequate in scope and quality to fulfill the dissertation requirements for the degree of Doctor of Philosophy. _____________________________________________ ________________ Michael J. Laszlo, Ph.D. Date Chairperson of Dissertation Committee _____________________________________________ ________________ Francisco J. Mitropoulos, Ph.D. Date Dissertation Committee Member _____________________________________________ ________________ Amon B. -
Design Pattern Driven Development of Model Transformations
DESIGN PATTERN DRIVEN DEVELOPMENT OF MODEL TRANSFORMATIONS by HUSEYIN ERGIN JEFF GRAY, COMMITTEE CHAIR JEFFREY CARVER RALF LAEMMEL RANDY SMITH EUGENE SYRIANI SUSAN VRBSKY A DISSERTATION Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science in the Graduate School of The University of Alabama TUSCALOOSA, ALABAMA 2017 Copyright Huseyin Ergin 2017 ALL RIGHTS RESERVED ABSTRACT Model-Driven Engineering (MDE) is considered a well-established software development ap- proach that uses abstraction to bridge the gap between the problem space and the software implementation. These abstractions are represented by models that make the validation of the real system easier. In MDE, many problems are solved using model transformation, which is a paradigm that manipulates high-level models to translate, evolve, or simulate them. However, the development of a model transformation for a specific problem is still a hard task. The main reason is the lack of a development process where transformations must be designed before implemented. Design patterns provide experiential reuse to soft- ware engineers when faced with recurring problems. In the literature, design patterns have been used to generate partially reusable software designs in order to help developers. There are many design patterns focused development methodologies proposed. However, most of them specialize in object-oriented design patterns. Given the various contexts in which de- sign patterns have been applied, model transformations may also benefit from a patterns approach. Although several studies have proposed design patterns for model transforma- tion, there is still no accepted common language to express them or a methodology that places design patterns at the heart of the development of model transformations. -
Iterator Design Pattern Copyright C 2016 by Linda Marshall and Vreda Pieterse
Department of Computer Science Tackling Design Patterns Chapter 15: Iterator Design Pattern Copyright c 2016 by Linda Marshall and Vreda Pieterse. All rights reserved. Contents 15.1 Introduction ................................. 2 15.2 Iterator Design Pattern .......................... 2 15.2.1 Identification . 2 15.2.2 Problem . 2 15.2.3 Structure . 3 15.2.4 Participants . 3 15.3 Cohesion ................................... 4 15.4 Iterator Pattern Explained ........................ 4 15.4.1 Design . 4 15.4.2 Improvements achieved . 5 15.4.3 Disadvantage . 5 15.4.4 Real world example . 6 15.4.5 Related Patterns . 6 15.5 Implementation Issues ........................... 7 15.5.1 Accessing the elements of the aggregate . 7 15.5.2 Additional functionality . 7 15.5.3 Internal and External iterators . 8 15.5.4 Allocation on the heap or on the stack . 8 15.5.5 Using C++ STL Iterators . 8 15.6 Example .................................... 11 15.7 Exercises ................................... 12 References ....................................... 13 1 15.1 Introduction To iterate means to repeat. In software it may be implemented using recursion or loop structures such as for-loops and while-loops. A class that provides the functionality to support iteration is called an iterator. The term aggregate is used to refer to a collection of objects. In software a collection may be implemented in an array, a vector, a binary tree, or any other data structure of objects. The iterator pattern is prescriptive about how aggregates and their iterators should be implemented. Two general principles are applied in the iterator design pattern. The first is a prominent principle of good design namely separation of concerns.