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Reviewer: Donald Quentin Marcus Fay

The style of writing in this book is clear and fluent. The authkr has introduced many terms that are already becoming accepted as standard in the object-oriented programming community. There are many highly quotable extracts throughout this stimulating technical book, which describes (1) the general concepts of object-oriented programming, (2) the main features of the programming language, Objective-C, and (3) the author's ideas about how computing might develop, with an emphasis on distributed office systems. The predominant theme is Objective-C, but this should not deter the enthusiasts of another object-oriented programming language from studying and using this book. Objective-C is used successfully to clearly explain general principles. For instance, a reader wanting to improve on a basic knowledge of the philosophy of Smalltalk will find this book useful. It is an advantage for the reader to have a good knowledge of C and a familiarity with UNIX, although knowledge of these is not essential to an understanding of the book. The references to other published material are given as footnotes at the bottom of the page on which they are quoted. A few more references would have been helpful; for instance, on p. 158 Trygve Reenskaug and Larry Tesler are mentioned with regard to their contributions to the model-view-controller paradigm, but no published work is quoted. One of the terms introduced by the author that is becoming widely used is “Software-IC”; this is backed up throughout the book by icons looking like integrated circuits to represent software modules. There are some places in the book where the analogy between hardware and software modules is perhaps taken too far; the general idea is reasonable, but some of the details do not match as well as is implied. There is much debate and discussion elsewhere about the advantages of having a hybrid language such as Objective-C. One of the arguments given in favor is that “. . . a hybrid object-oriented language can be used to develop code that is simultaneously reusable and highly machine-efficient. Message-based encapsulation is a tool, not a panacea, and there are times when it should be laid aside in favor of conventional programming techniques.” The book also includes some discussion of problems such as the current lack of the equivalent of the Block class of Smalltalk, but the resulting run-time advantages are well argued. There were one or two places where in a first skim through the book I failed to grasp the implication of the terminology. One example is the author's use of “+” and “?” markers to introduce factory methods and instance methods, respectively (see p. 81). Another was the use of the terms “passivation” and “activation” to describe the saving of data and their subsequent retrieval as a sequential file of text characters; passivation is more familiar to the Smalltalk programmer as “storeOn:,” or for classes as “fileOutOn: .” The chapter titles are as follows: :9N(1)System Building (2)Why Object-Oriented Programming__ __ (3)What is Object-Oriented Programming__ __ Smalltalk-80, Ada, C++, Summary (4)Objects, Messages, and Encapsulation (5)Classes, Inheritance, and Class Categories (6)Dependency Graph Exercise (7)Foundation Classes (8)Collection Classes (9)Iconic User Interfaces (10)Different Tools for Other Jobs Appendix A:Specification Sheets for Classes Appendix B:Hand-Coded Dependency Graph Application The level of presentation is of a consistent standard, and is suitable for the practitioner in the field or for a final-year undergraduate student. New ideas are introduced in this book that are now gaining general acceptability, and the established ideas of object-oriented programming are well surveyed and summarized. The Index pointed me to all the items I wanted to search for, but it could not point me to a discussion on how recursion in data structures could be detected and processed in passivation. The typography is good, and sufficient examples are included in relation to the material. In short, this is an excellent book.