Learn Objective-C Java Developers

Total Page:16

File Type:pdf, Size:1020Kb

Learn Objective-C Java Developers CYAN YELLOW SPOT MATTE MAGENTA BLACK PANTONE 123 C BOOKS FOR PROFESSIONALS BY PROFESSIONALS® Companion eBook Available Turn Java Expertise into Mac OS X • Learn Objective-C, the language of native Mac and iPhone apps, by leveraging Objective-CLearn the Java programming skills you already have. and iPhone App Productivity • Learn to use Apple’s development environment, including just enough Cocoa and Xcode. It’s the professional’s express route to Mac and iPhone developer proficiency. • Learn by working through the exercises and then keep returning for reference and further study. You’ll find everything conveniently organized so you can reference techniques by design pattern. e all love Java, but Mac OS X is looking awfully cool these days and iPhone OS de- Wvelopment is the most exciting new environment since, well…, since Java! If only there were a way to avoid learning objective-C. If you’re a Javahead, you probably know a lot more about objective-C than you think. The two languages are full of similarities and that’s why we’ve published Learn Objective-C for Java Developers, your shortcut to Mac and iphone development productivity. Both languages are object-oriented, use similar inheritance models, string classes, garbage collection, serialization, threads, introspection, and communications. They also embrace proven design patterns like Model-View-Controller and property accessors. You’re already a for good portion of the way there and you haven’t even opened this book! We’ll show you how to use what you know about Java to understand and become quickly Developers Java proficient in Objective-C. Most important, we’ll show you how to take advantage of features unique to Objective-C and incorporate them into your designs. Don’t waste your hard-earned Java knowledge by starting over in kindergarten. Move yourself to the head of the class and catapult over the Objective-C learning curve. You’ll be writing Mac OS X and iPhone apps faster than you ever imagined possible. James Bucanek has over 25 years of experience in software and systems development. Having made the transition to Mac OS X many years ago, he has never looked back. Learn Objective-C for Java Developers RELATED TITLES Bucanek James Bucanek COMPANION eBOOK SEE LAST PAGE FOR DETAILS ON $10 eBOOK VERSION ISBN 978-1-4302-2369-6 53999 US $39.99 Shelve in Mac Development SOURCE CODE ONLINE User level: www.apress.com Intermediate–Advanced 9 781430223696 this print for content only—size & color not accurate Trim: 7.5 x 9.25 spine =0.96875" 520 page count Download at WoweBook.Com ■ CONTENTS Learn Objective-C for Java Developers ■ ■ ■ James Bucanek Download at WoweBook.Com xxv ■ CONTENTS Learn Objective-C for Java Developers Copyright © 2009 by James Bucanek All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of the copyright owner and the publisher. ISBN-13 (pbk): 978-1-4302-2369-6 ISBN-13 (electronic): 978-1-4302-2370-2 Printed and bound in the United States of America 9 8 7 6 5 4 3 2 1 Trademarked names may appear in this book. Rather than use a trademark symbol with every occurrence of a trademarked name, we use the names only in an editorial fashion and to the benefit of the trademark owner, with no intention of infringement of the trademark. Lead Editors: Clay Andres, Douglas Pundick Technical Reviewer: Evan DiBiase Editorial Board: Clay Andres, Steve Anglin, Mark Beckner, Ewan Buckingham, Tony Campbell, Gary Cornell, Jonathan Gennick, Jonathan Hassell, Michelle Lowman, Matthew Moodie, Jeffrey Pepper, Frank Pohlmann, Douglas Pundick, Ben Renow-Clarke, Dominic Shakeshaft, Matt Wade, Tom Welsh Project Manager: Kylie Johnston Copy Editor: Elizabeth Berry Compositor: Lynn L’Heureux Indexer: Ann Rogers/Ron Strauss Artist: April Milne Cover Designer: Anna Ishchenko Manufacturing Director: Michael Short Distributed to the book trade worldwide by Springer-Verlag New York, Inc., 233 Spring Street, 6th Floor, New York, NY 10013. Phone 1-800-SPRINGER, fax 201-348-4505, e-mail orders- [email protected], or visit http://www.springeronline.com. For information on translations, please e-mail [email protected], or visit http://www.apress.com. Apress and friends of ED books may be purchased in bulk for academic, corporate, or promotional use. eBook versions and licenses are also available for most titles. For more information, reference our Special Bulk Sales–eBook Licensing web page at http://www.apress.com/info/bulksales. The information in this book is distributed on an “as is” basis, without warranty. Although every precaution has been taken in the preparation of this work, neither the author(s) nor Apress shall have any liability to any person or entity with respect to any loss or damage caused or alleged to be caused directly or indirectly by the information contained in this work. The source code for this book is available to readers at http://www.apress.com. ii Download at WoweBook.Com ■ CONTENTS AT A GLANCE To the memories of my brother, John, and my father, “Dr. B.” iii Download at WoweBook.Com ■ CONTENTS Contents at a Glance About the Author ........................................................................................................ xxi About the Technical Reviewer ................................................................................. xxii Acknowledgments ................................................................................................... xxiii Introduction ................................................................................................................xiv PART 1 ■ ■ ■ Language Chapter 1: Introduction ............................................................................................. 3 Chapter 2: Java and C: Key Differences ................................................................... 11 Chapter 3: Welcome to Objective-C ........................................................................ 27 Chapter 4: Creating an Xcode Project ..................................................................... 55 Chapter 5: Exploring Protocols and Categories ...................................................... 75 Chapter 6: Sending Messages .................................................................................. 87 Chapter 7: Making Friends with nil ....................................................................... 103 PART 2 ■ ■ ■ Translating Technologies Chapter 8: Strings and Primitive Values ................................................................ 117 Chapter 9: Garbage Collection ............................................................................... 135 Chapter 10: Introspection ...................................................................................... 147 Chapter 11: Files ..................................................................................................... 163 Chapter 12: Serialization ........................................................................................ 185 Chapter 13: Communicating Near and Far .......................................................... 211 Chapter 14: Exception Handling ........................................................................... 239 iv Download at WoweBook.Com ■ CONTENTS AT A GLANCE Chapter 15: Threads ............................................................................................... 257 PART 3 ■ ■ ■ Programming Patterns Chapter 16: Collection Patterns ............................................................................. 287 Chapter 17: Delegation Pattern ............................................................................. 315 Chapter 18: Provider/Subscriber Pattern ............................................................. 325 Chapter 19: Observer Pattern ................................................................................ 339 Chapter 20: Model-View-Controller Pattern ........................................................ 353 Chapter 21: Lazy Initialization Pattern ................................................................. 403 Chapter 22: Factory Pattern ................................................................................... 411 Chapter 23: Singleton Pattern ................................................................................ 429 PART 4 ■ ■ ■ Advanced Objective-C Chapter 24: Memory Management ....................................................................... 435 Chapter 25: Mixing C and Objective-C .................................................................. 457 Chapter 26: Runtime .............................................................................................. 465 Index ......................................................................................................................... 477 v Download at WoweBook.Com Download at WoweBook.Com ■ CONTENTS AT A GLANCE Contents About the Author ........................................................................................................ xxi About the Technical Reviewer ................................................................................. xxii Acknowledgments ................................................................................................... xxiii Introduction ................................................................................................................xiv PART 1 ■ ■ ■ Language Chapter
Recommended publications
  • Preview Objective-C Tutorial (PDF Version)
    Objective-C Objective-C About the Tutorial Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. This is the main programming language used by Apple for the OS X and iOS operating systems and their respective APIs, Cocoa and Cocoa Touch. This reference will take you through simple and practical approach while learning Objective-C Programming language. Audience This reference has been prepared for the beginners to help them understand basic to advanced concepts related to Objective-C Programming languages. Prerequisites Before you start doing practice with various types of examples given in this reference, I'm making an assumption that you are already aware about what is a computer program, and what is a computer programming language? Copyright & Disclaimer © Copyright 2015 by Tutorials Point (I) Pvt. Ltd. All the content and graphics published in this e-book are the property of Tutorials Point (I) Pvt. Ltd. The user of this e-book can retain a copy for future reference but commercial use of this data is not allowed. Distribution or republishing any content or a part of the content of this e-book in any manner is also not allowed without written consent of the publisher. We strive to update the contents of our website and tutorials as timely and as precisely as possible, however, the contents may contain inaccuracies or errors. Tutorials Point (I) Pvt. Ltd. provides no guarantee regarding the accuracy, timeliness or completeness of our website or its contents including this tutorial. If you discover any errors on our website or in this tutorial, please notify us at [email protected] ii Objective-C Table of Contents About the Tutorial ..................................................................................................................................
    [Show full text]
  • Sound Invariant Checking Using Type Modifiers and Object Capabilities
    Sound Invariant Checking Using Type Modifiers and Object Capabilities. Isaac Oscar Gariano Victoria University of Wellington [email protected] Marco Servetto Victoria University of Wellington [email protected] Alex Potanin Victoria University of Wellington [email protected] Abstract In this paper we use pre existing language support for type modifiers and object capabilities to enable a system for sound runtime verification of invariants. Our system guarantees that class invariants hold for all objects involved in execution. Invariants are specified simply as methods whose execution is statically guaranteed to be deterministic and not access any externally mutable state. We automatically call such invariant methods only when objects are created or the state they refer to may have been mutated. Our design restricts the range of expressible invariants but improves upon the usability and performance of our system compared to prior work. In addition, we soundly support mutation, dynamic dispatch, exceptions, and non determinism, while requiring only a modest amount of annotation. We present a case study showing that our system requires a lower annotation burden compared to Spec#, and performs orders of magnitude less runtime invariant checks compared to the widely used ‘visible state semantics’ protocols of D, Eiffel. We also formalise our approach and prove that such pre existing type modifier and object capability support is sufficient to ensure its soundness. 2012 ACM Subject Classification Theory of computation → Invariants, Theory of computation → Program verification, Software and its engineering → Object oriented languages Keywords and phrases type modifiers, object capabilities, runtime verification, class invariants Digital Object Identifier 10.4230/LIPIcs.CVIT.2016.23 1 Introduction Object oriented programming languages provide great flexibility through subtyping and arXiv:1902.10231v1 [cs.PL] 26 Feb 2019 dynamic dispatch: they allow code to be adapted and specialised to behave differently in different contexts.
    [Show full text]
  • On Goto Statement in Basic
    On Goto Statement In Basic James spores his coeditor arrest lowse, but ribbony Clarence never perambulating so defenselessly. orFingered ferniest and after sold grapy Barry Jimmy sublime countermarches his microclimates so thwart? envelop snigs opinionatively. Is Skylar mismatched Download On Goto Statement In Basic pdf. Download On Goto Statement In Basic doc. Well before withthe statement recursion, basic, and look understandable like as labe not, usage i learned of. Normal to that precedence include support that the content goto basic;is a goto. back Provided them up by statementthe adjectives basic, novel the anddim knowsstatement exactly with be the in below. basic doesMany not and supported the active for on the goto vba. in theSkip evil the comes error asfrom on movesthe specified to go toworkbook go with thename _versionname_ to see the value home does page. not Activeprovided on byone this is withinsurvey? different Outline if ofa trailingbasic withinspace theor responding value if by thisto. Repaired page? Print in favor statement of code along so we with need recursion: to go with many the methods product. becomeThought of goto is startthousands running of intothe code?more readable Slightly moreand in instances vb. Definitely that runnot onprovided basic program, by a more goto explicit that construct,exponentiation, basic i moreinterpreter about? jump Stay to thatadd youthe workbookwhen goto name. basic commandPrediction gotoor go used, on statement we were basicnot, same moves page to the returns slightly isresults a boolean specific in toworkbook the trademarks name to of. the Day date is of.another Exactly if you what forgot you runa stack on in overflow basic does but misusingnot complete it will code isgenerally the window.
    [Show full text]
  • 7. Control Flow First?
    Copyright (C) R.A. van Engelen, FSU Department of Computer Science, 2000-2004 Ordering Program Execution: What is Done 7. Control Flow First? Overview Categories for specifying ordering in programming languages: Expressions 1. Sequencing: the execution of statements and evaluation of Evaluation order expressions is usually in the order in which they appear in a Assignments program text Structured and unstructured flow constructs 2. Selection (or alternation): a run-time condition determines the Goto's choice among two or more statements or expressions Sequencing 3. Iteration: a statement is repeated a number of times or until a Selection run-time condition is met Iteration and iterators 4. Procedural abstraction: subroutines encapsulate collections of Recursion statements and subroutine calls can be treated as single Nondeterminacy statements 5. Recursion: subroutines which call themselves directly or indirectly to solve a problem, where the problem is typically defined in terms of simpler versions of itself 6. Concurrency: two or more program fragments executed in parallel, either on separate processors or interleaved on a single processor Note: Study Chapter 6 of the textbook except Section 7. Nondeterminacy: the execution order among alternative 6.6.2. constructs is deliberately left unspecified, indicating that any alternative will lead to a correct result Expression Syntax Expression Evaluation Ordering: Precedence An expression consists of and Associativity An atomic object, e.g. number or variable The use of infix, prefix, and postfix notation leads to ambiguity An operator applied to a collection of operands (or as to what is an operand of what arguments) which are expressions Fortran example: a+b*c**d**e/f Common syntactic forms for operators: The choice among alternative evaluation orders depends on Function call notation, e.g.
    [Show full text]
  • Method Proxy-Based AOP in Scala
    Vol. 0, No. 0, Z Method Proxy-Based AOP in Scala Daniel Spiewak and Tian Zhao University of Wisconsin – Milwaukee, fdspiewak,[email protected] This paper describes a fully-functional Aspect-Oriented Programming framework in Scala – a statically typed programming language with object-oriented and func- tional features. This framework is implemented as internal domain-specific lan- guages with syntax that is both intuitive and expressive. The implementation also enforces some static type safety in aspect definitions. 1 INTRODUCTION Aspect-Oriented Programming (AOP) implementations such as AspectJ provide language extensions of pointcuts and advices to insert code of crosscutting concerns into the base program through bytecode transformation. In this paper, we describe a framework to implement an AOP extension to the Scala language [13] using higher-order functions as AOP proxies 1. This framework allows programmers to specify pointcuts and aspects using a Domain Specific Language (DSL) [5] embedded within Scala. Our technique uses Scala’s higher-order functions to intercept method calls with minimal syntactic overhead imposed on the base program. This framework allows developers to define pointcuts by specifying class types and method signatures. The framework also allows access to context variables, while aspects can insert advice code before or after the advised body. The rest of the paper is organized as follows: In Section2, we present the main idea using an example. Section3 explains the syntax of pointcuts and advices. Section4 ex- plains the implementation details. We discuss the benefits and tradeoffs of our framework in Section5. and related works are in Section6. 2 EXAMPLE AOP enables developers to write code that is modularized to a point beyond the capabil- ities of vanilla object-oriented design.
    [Show full text]
  • Gnu Smalltalk Library Reference Version 3.2.5 24 November 2017
    gnu Smalltalk Library Reference Version 3.2.5 24 November 2017 by Paolo Bonzini Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled \GNU Free Documentation License". 1 3 1 Base classes 1.1 Tree Classes documented in this manual are boldfaced. Autoload Object Behavior ClassDescription Class Metaclass BlockClosure Boolean False True CObject CAggregate CArray CPtr CString CCallable CCallbackDescriptor CFunctionDescriptor CCompound CStruct CUnion CScalar CChar CDouble CFloat CInt CLong CLongDouble CLongLong CShort CSmalltalk CUChar CByte CBoolean CUInt CULong CULongLong CUShort ContextPart 4 GNU Smalltalk Library Reference BlockContext MethodContext Continuation CType CPtrCType CArrayCType CScalarCType CStringCType Delay Directory DLD DumperProxy AlternativeObjectProxy NullProxy VersionableObjectProxy PluggableProxy SingletonProxy DynamicVariable Exception Error ArithmeticError ZeroDivide MessageNotUnderstood SystemExceptions.InvalidValue SystemExceptions.EmptyCollection SystemExceptions.InvalidArgument SystemExceptions.AlreadyDefined SystemExceptions.ArgumentOutOfRange SystemExceptions.IndexOutOfRange SystemExceptions.InvalidSize SystemExceptions.NotFound SystemExceptions.PackageNotAvailable SystemExceptions.InvalidProcessState SystemExceptions.InvalidState
    [Show full text]
  • AP Computer Science Basic OOP — Implementing Classes
    AP Computer Science Basic OOP — Implementing Classes ORIENTATION Object-oriented programming (OOP) refers to the organization of data into classes, categories that represent a given type of “object.” An object can be a model of a real-life thing like a car, a six-sided die, or a person, or it can be a representation of something more abstract like a point in space, a menu item, or a digital clipboard. An object that belongs to a given class is called an instance of that class, and any instance of a class keeps track of its state using instance variables, or attributes. The object is created when its constructor is called, and can be interacted with by calling its methods, which may access data (accessor methods, or “getters”) or alter the object’s data (mutator methods, or “setters”). There are two important theoretical concepts in OOP: abstraction and encapsulation. Objects and the classes they belong to act as abstractions of the things they represent: a Java class called Person isn’t actually a person, of course, but a simplified representation of a person in terms of a limited number of qualities (name and age, perhaps). Other details such as hair color, nationality, and gender identity aren’t included in our abstraction of a person. Encapsulation refers to the way that a class and its methods hide away the details of a process. Someone using a QuadraticFormula class can call the hasSolutions() method to find out whether their equation has solutions without knowing what a discriminant is. The programmer and the class she has written have hidden that information away in a metaphorical “black box.” Basic OOP consists primarily of implementing classes: writing the JavaDocs, class header, constructors, attributes, and methods for an object as specified.
    [Show full text]
  • Secure the Clones - Static Enforcement of Policies for Secure Object Copying Thomas Jensen, Florent Kirchner, David Pichardie
    Secure the Clones - Static Enforcement of Policies for Secure Object Copying Thomas Jensen, Florent Kirchner, David Pichardie To cite this version: Thomas Jensen, Florent Kirchner, David Pichardie. Secure the Clones - Static Enforcement of Policies for Secure Object Copying. ESOP 2011, 2011, Saarbrucken, Germany. hal-01110817 HAL Id: hal-01110817 https://hal.inria.fr/hal-01110817 Submitted on 28 Jan 2015 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Secure the Clones * Static Enforcement of Policies for Secure Object Copying Thomas Jensen, Florent Kirchner, and David Pichardie INRIA Rennes – Bretagne Atlantique, France [email protected] Abstract. Exchanging mutable data objects with untrusted code is a delicate matter because of the risk of creating a data space that is accessible by an attacker. Consequently, secure programming guidelines for Java stress the importance of using defensive copying before accepting or handing out references to an inter- nal mutable object. However, implementation of a copy method (like clone()) is entirely left to the programmer. It may not provide a sufficiently deep copy of an object and is subject to overriding by a malicious sub-class. Currently no language-based mechanism supports secure object cloning.
    [Show full text]
  • The Latest IBM Z COBOL Compiler: Enterprise COBOL V6.2!
    The latest IBM Z COBOL compiler: Enterprise COBOL V6.2! Tom Ross Captain COBOL SHARE Providence August 7,2017 1 COBOL V6.2 ? YES! • The 4 th release of the new generation of IBM Z COBOL compilers • Announced: July 17, 2017 • The same day as IBM z14 hardware…coincidence? • GA: September 8, 2017 • Compiler support for the new IBM z14 hardware and IBM z/OS V2.3 • Ability to exploit the new Vector Packed Decimal Facility of z14 • ‘OLD’ news: • COBOL V5 EOM Sept 11, 2017 (announced Dec 6, 2016) • EOS for COBOL V4 ‘might’ be earlier than 2020, still discussing 2 COBOL V6.2 ? What else does it have? • New and changed COBOL statements, such as the new JSON PARSE statement • Support of COBOL 2002/2014 standards with the addition of the COBOL Conditional Compilation language feature • New and changed COBOL options for increased flexibility • Improved compiler listings with compiler messages at the end of the listing as in previous releases of the compiler • Improved interfaces to optional products and tools such as IBM Debug for z Systems (formerly Debug Tool for z/OS) and IBM Application Discovery and Delivery Intelligence (formerly EzSource) • Compile-time and runtime performance enhancements • Improved usability of the compiler in the z/OS UNIX System Services environment 3 Vector Packed Decimal Facility of z14 • Enterprise COBOL V6.2 adds support for exploiting the new Vector Packed Decimal Facility in z14 through the ARCH(12) compiler option. • The Vector Packed Decimal Facility allows the dominant COBOL data types, packed and zoned decimal, to be handled in wide 16-byte vector registers instead of in memory.
    [Show full text]
  • Programming Reference Guide
    Programming Reference Guide REFERENCE GUIDE RG-0006-01 1.9 en-US ENGLISH Important User Information Disclaimer The information in this document is for informational purposes only. Please inform HMS Networks of any inaccuracies or omissions found in this document. HMS Networks disclaims any responsibility or liability for any errors that may appear in this document. HMS Networks reserves the right to modify its products in line with its policy of continuous product development. The information in this document shall therefore not be construed as a commitment on the part of HMS Networks and is subject to change without notice. HMS Networks makes no commitment to update or keep current the information in this document. The data, examples and illustrations found in this document are included for illustrative purposes and are only intended to help improve understanding of the functionality and handling of the product. In view of the wide range of possible applications of the product, and because of the many variables and requirements associated with any particular implementation, HMS Networks cannot assume responsibility or liability for actual use based on the data, examples or illustrations included in this document nor for any damages incurred during installation of the product. Those responsible for the use of the product must acquire sufficient knowledge in order to ensure that the product is used correctly in their specific application and that the application meets all performance and safety requirements including any applicable laws, regulations, codes and standards. Further, HMS Networks will under no circumstances assume liability or responsibility for any problems that may arise as a result from the use of undocumented features or functional side effects found outside the documented scope of the product.
    [Show full text]
  • FORTRAN 77 Language Reference
    FORTRAN 77 Language Reference FORTRAN 77 Version 5.0 901 San Antonio Road Palo Alto, , CA 94303-4900 USA 650 960-1300 fax 650 969-9131 Part No: 805-4939 Revision A, February 1999 Copyright Copyright 1999 Sun Microsystems, Inc. 901 San Antonio Road, Palo Alto, California 94303-4900 U.S.A. All rights reserved. All rights reserved. This product or document is protected by copyright and distributed under licenses restricting its use, copying, distribution, and decompilation. No part of this product or document may be reproduced in any form by any means without prior written authorization of Sun and its licensors, if any. Portions of this product may be derived from the UNIX® system, licensed from Novell, Inc., and from the Berkeley 4.3 BSD system, licensed from the University of California. UNIX is a registered trademark in the United States and in other countries and is exclusively licensed by X/Open Company Ltd. Third-party software, including font technology in this product, is protected by copyright and licensed from Sun’s suppliers. RESTRICTED RIGHTS: Use, duplication, or disclosure by the U.S. Government is subject to restrictions of FAR 52.227-14(g)(2)(6/87) and FAR 52.227-19(6/87), or DFAR 252.227-7015(b)(6/95) and DFAR 227.7202-3(a). Sun, Sun Microsystems, the Sun logo, SunDocs, SunExpress, Solaris, Sun Performance Library, Sun Performance WorkShop, Sun Visual WorkShop, Sun WorkShop, and Sun WorkShop Professional are trademarks or registered trademarks of Sun Microsystems, Inc. in the United States and in other countries.
    [Show full text]
  • Lazy Object Copy As a Platform for Population-Based Probabilistic Programming
    Lazy object copy as a platform for population-based probabilistic programming Lawrence M. Murray Uber AI Abstract This work considers dynamic memory management for population-based probabilistic programs, such as those using particle methods for inference. Such programs exhibit a pattern of allocating, copying, potentially mutating, and deallocating collections of similar objects through successive generations. These objects may assemble data structures such as stacks, queues, lists, ragged arrays, and trees, which may be of random, and possibly unbounded, size. For the simple case of N particles, T generations, D objects, and resampling at each generation, dense representation requires O(DNT ) memory, while sparse representation requires only O(DT + DN log DN) memory, based on existing theoretical results. This work describes an object copy-on-write platform to automate this saving for the programmer. The core idea is formalized using labeled directed multigraphs, where vertices represent objects, edges the pointers between them, and labels the necessary bookkeeping. A specific labeling scheme is proposed for high performance under the motivating pattern. The platform is implemented for the Birch probabilistic programming language, using smart pointers, hash tables, and reference-counting garbage collection. It is tested empirically on a number of realistic probabilistic programs, and shown to significantly reduce memory use and execution time in a manner consistent with theoretical expectations. This enables copy-on-write for the imperative programmer, lazy deep copies for the object-oriented programmer, and in-place write optimizations for the functional programmer. 1 Introduction Probabilistic programming aims at better accommodating the workflow of probabilistic modeling and inference in general-purpose programming languages.
    [Show full text]