Visual Basic Design Patterns: VB 6.0 and VB.NET

Description

• Copyright 2002
• Edition: 1st

• Book
• ISBN-10: 0-201-70265-7
• ISBN-13: 978-0-201-70265-1

Design patterns provide programmers with a convenient way to reuse object-oriented code across projects and between programmers, offering easy, time-saving solutions to commonly recurring problems in software design. A practical guide to writing Visual Basic (VB6 and VB.NET) programs using some of the most common design patterns, Visual Basic Design Patterns is a tutorial for people who want to learn about design patterns and how to use them in their work. This book also provides a convenient way for VB6 programmers to migrate to VB.NET and use its more powerful object-oriented features.

Written from a Visual Basic perspective, this book intends to make you comfortable with using design patterns by laying out the concept of patterns in a practical fashion. Organized as a series of short chapters that each describe a design pattern, Visual Basic Design Patterns provides one or more complete working visual examples of programs using that pattern, along with UML diagrams illustrating how the classes interact. Each example is a visual program that you can run and study on the companion CD making the pattern as concrete as possible. Programmers using this book will see significant improvement in their work by employing the following key concepts:

• Applying "tried-and-true" object-oriented design patterns in Visual Basic applications.
• Helping advance programming skills with the power of patterns.
• Understanding the interactions between classes through the use of UML diagrams.
• Getting comfortable using design patterns effectively and start using them in day-to-day Visual Basic programming.

The idea behind design patterns is simple: it's a catalogue of common interactions between objects that programmers have found useful, enabling them to quickly and easily employ them in their programs. Visual Basic Design Patterns provides practical advice on how to use these patterns in everyday programming.

0201702657B07122001

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Table of Contents

Preface.


Acknowledgements.

I. OBJECT-ORIENTED PROGRAMMING IN VB.

1. What Are Design Patterns?

Defining Design Patterns.

The Learning Process.

Studying Design Patterns.

Notes on Object Oriented Approaches.

VB Design Patterns.

How this Book is Organized.

2. UML Diagrams.

Inheritance.

Interfaces.

Composition.

Annotation.

WithClass UML Diagrams.

Visual Basic Project Files.

3. Using Classes and Objects in VB.

A Simple Temperature Conversion Program.

Building a Temperature Class.

Converting to Kelvin.

Putting the Decisions into the Temperature Class.

Using Classes for Format and Value Conversion.

Handling Unreasonable Values.

A String Tokenizer Class.

Classes as Objects.

Class Containment.

Class Initialization.

Classes and Properties.

Another Interface Example—The Voltmeter.

A vbFile Class.

Programming Style in Visual Basic.

Summary.

4. Object-Oriented Programming.

Building VB Objects.

Creating Instances of Objects.

A VB Measurement Program.

Methods Inside Objects.

Variables.

Passing Arguments by Reference and by Value.

Object Oriented Jargon.

5. Building Your Own VB Control.

A Highlighted Text Field.

Resizing a User Control.

Testing Your HiText Controls.

Adding Properties and Methods to User Controls.

Compiling a User Control.

Summary.

Program on the CD-ROM.

6. Inheritance and Interfaces.

Interfaces.

An Investment Simulator.

Writing the Simulator.

Indicators for Using an Interface.

Reusing Common Methods.

Hidden Interfaces.

Summary.

Programs on the CD-ROM.

7. Introduction to VB.NET.

Syntax Differences in VB.NET.

Improved Function Syntax.

Variable Declarations and Scoping.

Objects in VB.NET.

Compiler Options.

Numbers in VB.NET.

Properties in VB6 and VB.NET.

Shorthand Equals Syntax.

Managed Languages and Garbage Collection.

Classes in VB.NET.

Building a VB7 Application.

The Simplest Window Program in VB.NET.

Inheritance.

Constructors.

Drawing and Graphics in VB.NET.

Tooltips and Cursors.

Overloading.

Inheritance.

Namespaces.

Creating a Square from a Rectangle.

Public, Private, and Protected.

Overriding Methods in Derived Classes.

Overloading and Shadowing.

Overriding Windows Controls.

Interfaces.

Summary.

Programs on the CD-ROM.

8. Arrays, Files and Exceptions in VB.Net.

Arrays.

Collection Objects.

ArrayLists.

Hashtables.

SortedLists.

Exceptions.

Multiple Exceptions.

Throwing Exceptions.

File Handling.

The File Object.

Reading a Text File.

Writing a Text File.

Exceptions in File Handling.

Testing for End of File.

The FileInfo Class.

A vbFile Class.

Programs on the CD-ROM.

II. CREATIONAL PATTERNS.

9. The Simple Factory Pattern.

How a Simple Factory Works.

Sample Code.

The Two Derived Classe.

Building the Simple Factory.

Using the Factory.

Writing the Factory Pattern in VB.NET.

Factory Patterns in Math Computation.

Programs on the CD-ROM.

10. The Factory Method.

The Swimmer class.

The Events Classes.

Straight Seeding.

Circle Seeding.

Our Seeding Program.

Other Factories.

The Seeding Program in VB7.

When to Use a Factory Method.

Programs on the CD-ROM.

11. The Abstract Factory Pattern.

A GardenMaker Factory.

How the User Interface Works.

Creating an Abstract Factory Using VB7.

The Picture Box.

Handling the RadioButton and Button Events.

Adding More Classes.

Consequences of Abstract Factory.

Programs on the CD-ROM.

12. The Singleton Pattern.

Creating Singleton Using a Static Method.

Catching the Error.

Providing a Global Point of Access to a Singleton.

The MSComm Control as a Singleton.

Available Ports.

Writing a Singleton in VB.NET.

Using a Private Constructor.

Error Handling in Our Singleton.

A VB.NET SpoolDemo Program.

The Global Point of Access.

Other Consequences of the Singleton Pattern.

Programs on Your CD-ROM.

13. The Builder Pattern.

An Investment Tracker.

Calling the Builders.

The List Box Builder.

The Checkbox Builder.

Writing a Builder in VB.NET.

The Stock Factory.

The CheckChoice Class.

The ListboxChoice Class.

Using the Items Collection in the ListBox Control.

The Final Choice.

Consequences of the Builder Pattern.

Programs on the CD-ROM.

14. The Prototype Pattern.

Cloning in Visual Basic.

Using the Prototype.

Using the Prototype Pattern.

Additional Methods in Subclasses.

Dissimilar Classes with the Same Interface.

Prototype Managers.

Writing a Prototype in VB7.

Consequences of the Prototype Pattern.

Programs on the CD-ROM.

Summary of Creational Patterns.

III. Structural Patterns.

15. The Adapter Pattern.

Moving Data between Lists.

Using the MSFlexGrid.

Using a TreeView.

The Object Adapter.

Two Way Adapters.

Using Adapters in VB7.

TreeView Adapters for VB.NET.

Adapting a DataGrid.

The Class Adapter.

Two-Way Adapters.

Object versus Class Adapters in VB.NET.

Pluggable Adapters.

Adapters in VB.

Programs on the CD-ROM.

16. The Bridge Pattern.

The visList Classes.

The Class Diagram.

Extending the Bridge.

ActiveX Controls as Bridges.

The Bridge Pattern in VB.NET.

The ListBox VisList Class.

The Grid VisList Class.

Loading the Data.

Changing the Data Side of the Bridge.

Consequences of the Bridge Pattern.

Programs on your CD-ROM.

17. The Composite Pattern.

An Implementation of a Composite.

Computing Salaries.

The Employee Classes.

The Subords Class.

The Boss Class.

Building the Employee Tree.

Self-Promotion.

Doubly Linked Lists.

Consequences of the Composite Pattern.

A Simple Composite.

Composites in VB.

The Composite in VB.NET.

The Enumerator.

Multiple Boss Constructors.

Other Implementation Issues.

Programs on the CD-ROM.

18. The Decorator Pattern.

Decorating a CoolButton.

Using a Decorator.

Using ActiveX Controls as Decorators.

A Decorator In VB.NET.

Nonvisual Decorators.

Decorators, Adapters and Composites.

Consequences of the Decorator Pattern.

Programs on the CD-ROM.

19. The Facade Pattern.

What is a Database?

Getting Data out of Databases.

Kinds of Databases.

ODBC.

Microsoft Database Connection Strategies.

Database Structure.

The DBase Class.

Building the Facade Classes.

The Stores Class.

Building the Stores and Foods Tables.

Building the Price Table.

Building the Price Query.

Summary of the Facade Pattern.

ADO Database Access in VB6.

The ADO Connection.

Adding and Seeking Rows Table Rows.

Using the ADO Extensions.

The ADO Dbase Class.

Database Access in VB.NET.

Using ADO.NET.

Connecting to a Database.

Reading Data from a Database Table.

Executing a Query.

Deleting the Contents of a Table.

Adding Rows to Database Tables Using ADO.NET.

Making the VB.NET ADO Facade.

The DBTable class.

Creating Classes for Each Table.

Storing the Prices.

Loading the Database Tables.

The Final Application.

What Constitutes the Facade?

Consequences of the Facade.

Programs on the CD-ROM.

20. The Flyweight Pattern.

Discussion.

Example Code.

The Class Diagram.

Selecting A Folder.

Writing a Flyweight Folder in VB.NET.

Flyweight Uses in VB.

Sharable Objects.

Copy-on-Write Objects.

Programs on the CD-ROM.

21. The Proxy Pattern.

Sample Code.

Writing a Proxy in VB.Net.

Proxies in VB.

Copy-on-Write.

Comparison with Related Patterns.

Programs on the CD-ROM.

Summary of Structural Patterns.

IV. BEHAVIORAL PATTERNS.

22. Chain of Responsibility.

Applicability.

Sample Code.

The List Boxes.

Programming a Help System.

Receiving the Help Command.

A Chain or a Tree?

Chain of Responsibility in VB.NET.

Kinds of Requests.

Examples in VB.

Consequences of the Chain of Responsibility.

Programs on the CD-ROM.

23. The Command Pattern.

Motivation.

Command Objects.

Building Command Objects.

Arrays of Commands.

Consequences of the Command Pattern.

Providing Undo.

The Command Pattern in VB.NET.

The CommandHolder Interface.

Handling Undo Commands in VB.NET.

The Command Pattern in the VB Language.

Programs on the CD-ROM.

24. The Interpreter Pattern.

Motivation.

Applicability.

A Simple Report Example.

Interpreting the Language.

Objects Used in Parsing.

Reducing the Parsed Stack.

Implementing the Interpreter Pattern.

The Syntax Tree.

Building an Interpreter in VB.

The Parse Objects.

Consequences of the Interpreter Pattern.

Programs on the CD-ROM.

25. The Iterator Pattern.

Motivation.

Sample VB6 Code.

Fetching an Iterator.

Filtered Iterators.

The Filtered Iterator.

Iterators in VB.NET.

Consequences of the Iterator Pattern.

Programs on the CD-ROM.

26. The Mediator Pattern.

An Example System.

Interactions between Controls.

Sample Code.

Initialization of the System.

Mediators and Command Objects.

The Mediator in VB.Net.

Initialization.

Handling the Events for the New Controls.

Consequences of the Mediator Pattern.

Single Interface Mediators.

Implementation Issues.

Programs on the CD-ROM.

27. The Memento Pattern.

Motivation.

Implementation.

Sample Code.

A Cautionary Note.

Command Objects in the User Interface.

Handling Mouse and Paint Events.

Writing a Memento in VB.NET.

Consequences of the Memento.

Programs on the CD-ROM.

28. The Observer Pattern.

Watching Colors Change.

Writing an Observer in VB.NET.

The Message to the Media.

Consequences of the Observer Pattern.

Programs on the CD-ROM.

29. The State Pattern.

Sample Code.

Switching Between States.

How the Mediator Interacts with the State Manager.

Handling the Fill State.

Handling the Undo List.

Filling Circles in VB.

A State Pattern in VB.NET.

Mediators and the God Class.

Consequences of the State Pattern.

State Transitions.

Programs on the CD-ROM.

30. The Strategy Pattern.

Motivation.

Sample Code.

The Context.

The Program Commands.

The Line and Bar Graph Strategies.

Drawing Plots in VB.

A Strategy Pattern in VB.NET.

Consequences of the Strategy Pattern.

Programs on the CD-ROM.

31. The Template Method Pattern.

Motivation.

Kinds of Methods in a Template Class.

Sample Code.

Drawing a Standard Triangle.

Drawing an Isosceles Triangle.

The Triangle Drawing Program.

Templates and Callbacks.

Summary and Consequences.

Programs on the CD-ROM.

32. The Visitor Pattern.

Motivation.

When to Use the Visitor Pattern.

Sample Code.

Visiting the Classes.

Visiting Several Classes.

Bosses are Employees Too.

Catch-All Operations with Visitors.

Double Dispatching.

Why Are We Doing This?

Traversing a Series of Classes.

Writing a Visitor in VB.

Consequences of the Visitor Pattern.

Programs on the CD-ROM.

Bibliography.
Index. 0201702657T11152001

Preface

This is a practical book that tells you how to write Visual Basic (VB6 and VB.NET) programs using some of the most common design patterns. It also serves as a quick introduction to programming in the new VB.NET version of the VB language. The pattern discussions are structured as a series of short chapters, each describing a design pattern and giving one or more complete working, visual-example programs that use that pattern. Each chapter also includes UML diagrams illustrating how the classes interact.

This book is not a "companion" book to the well-known Design Patterns text by the "Gang of Four." Instead, it is a tutorial for people who want to learn what design patterns are about and how to use them in their work. You do not have to have read Design Patterns to read this book, but when you are done here you may well want to read or reread it to gain additional insights.

In this book you will learn that design patterns are frequently used ways of organizing objects in your programs to make them easier to write and modify. You'll also see that by familiarizing yourself with them, you've gained some valuable vocabulary for discussing how your programs are constructed.

People come to appreciate design patterns in different ways--from the highly theoretical to the intensely practical--and when they finally see the great power of these patterns, an Aha! moment occurs. Usually this moment means that you suddenly have an internal picture of how that pattern can help you in your work.

In this book, we try to help you form that conceptual idea, or gestalt, by describing the pattern in as many ways as possible. The book is organized into six main sections: an introductory description, an introduction to VB.NET, and descriptions of patterns, grouped as creational, structural, and behavioral.

For each pattern, we start with a brief verbal description and then build simple example programs. Each of these examples is a visual program that you can run and examine to make the pattern as concrete a concept as possible. All of the example programs and their variations are on the companion CD-ROM, where you run them, change them, and see how the variations you create work.

We show that you can use design patterns effectively in VB6 and then show the same patterns in VB.NET (also called VB7). Since each of the examples consists of a number of VB files for each of the classes we use in that example, we also provide a VB project file for each example and place each example in a separate subdirectory to prevent any confusion. We place the VB.NET examples in a separate directory under each pattern. This book is based on the Beta-2 release of VB.Net. Any changes between this version and the final product will probably not be great. Consult the Addison-Wesley Web site for updates to any example code.

If you leaf through the book you'll see screen shots of the programs we developed to illustrate the design patterns, providing yet another way to reinforce your learning of these patterns. In addition, you'll see UML diagrams of these programs, illustrating the interactions between classes in yet another way. UML diagrams are just simple box-and-arrow illustrations of classes and their inheritance structure, where arrows point to parent classes, and dotted arrows point to interfaces. And if you're not yet familiar with UML, we provide a simple introduction in the secondchapter.

When you finish this book you'll be comfortable with the basics of design patterns and will be able to start using them in your day-to-day Visual Basic programming work.

James W. Cooper
Nantucket, MA
Wilton, CT
Maui, HI
October, 2001

0201702657P11152001

Index

A

a array, sorting elements, 61-62

Abstract class, 314

Abstract classes, 7-8

Factory Method pattern, 113

Abstract Factory pattern, 103, 180

adding classes, 136

GardenMaker Factory, 127-129

isolating concrete classes, 136

subclasses, 136

VB.NET GardenMaker program, 131-135

Abstract methods, 12

AbstractDecorator interface, 233

AbstractEmployee class, 213-214, 221-222

AbstractEmployee interface, 221, 224-225

AbstractExpression class, 347, 348

program, 136

Abstraction, 197

accept method, 448-453, 455-456, 458

Access, 244

AccessException exception, 94

Accessor functions, 41

ActionVerb class, 350

ActiveX Control command, 43

ActiveX controls

as bridges, 204

as decorators, 236

Adapter pattern, 181, 298

class adapters, 194-195

DataGrid control, 192-193

moving data between lists, 183-185

MSFlexGrid control, 185-187

pluggable adapters, 196

TreeView adapters, 191-192

TreeView control, 187-188

two-way adapters, 195

VB.NET usage, 189-190

Adapters, 183, 239

program, 196

add method, 92, 215, 223, 328

addArgsToVerb method, 351

addChain method, 306

AddItem method, 185

AAddNew method, 245, 259

addNode method, 220

Address object, 149

addText method, 186, 187, 191, 195

ADO (ActiveX Data Objects), 245

ADO databases

accessing in VB6, 256-264

adding columns to tables, 260

adding rows to tables, 259

ADOX (ADO extensions), 259-260

Connection object, 258-259

DBase class, 260-262

finding rows matching criteria, 259

Indexer class, 262-264

primary key, 260

table creation, 259-260

ADOCommand object, 265

ADO.NET

adding rows to tables, 267-268

connecting to database, 265

deleting table contents, 266

executing queries, 266

reading data from table, 265

ADOX (ADO extensions), 256, 259-260

afterSelect event, 226

Age property, 30

AgeSwimData class, 172, 174

All buttons class, 303-304

Ancillary classes, 57

Annotation and UML diagrams, 15-16

AnnualGarden class, 129, 133

AppendText method, 99

Applications, switching states, 403

Approach, 244

ArgumentException exception, 94

ArgumentNullException exception, 94

ArithmeticException exception, 94

ArrayList class, 156, 158, 175, 208, 272, 342

ArrayList object, 91

Arrays, 89-91

collection objects, 91-93

of commands, 322-325

dynamic, 90

error conditions, 93

Hashtables, 91-92

index out-of-range statements, 93

relocating space in, 90

resizing, 90-91

SortedList class, 92

specifying contents of, 90

strings, 75

variable-length objects, 91-93

variables, 90

zero-based, 89, 91, 175

ASPs (Active Server Pages), 298

Attributes method, 99

Autoincrement property, 260

B

BarPlot class, 437

BarPlotStrategy class, 429, 432

.bas file type, 68

Base class

defining all methods in, 136

methods, 55

BaseClass class, 83

Behavioral design patterns, 6

Behavioral patterns, 301

Bitmap class, 296

BlueCommand class, 336

blueCommand object, 328

Bond class, 52-54

duplicated code, 55

inserting an instance of Equity class inside, 56

Bonds class, 152, 153, 157

BonsaiGarden class, 136

Booch, Grady, 11

Boss class, 216-218, 221, 225, 451-453, 457-458

Bosses class, 213

BossVisitor class, 455

Bridge class, 201, 202, 208

Bridge pattern, 181, 197-200

Abstraction, 197

ActiveX controls as bridges, 204

changing data side, 208-209

class diagram, 201

ConcreteImplementors, 197

consequences of, 210

extending Bridge class, 202

Implementor, 197

ListBox class, 206

loading data, 207

ProductTable class, 206-207

program, 210

Refined Abstraction, 197

VB.NET, 205-207

visList interface, 200-201

Bridger class, 197-198, 199, 201

Bridger interface, 205

program, 210

btnRed button, 319

Builder class, 150, 151

Builder pattern, 103, 149-150, 180

calling builders, 152-154

Check Box Builder, 154-155

CheckChoice class, 158-159

consequences of, 162

Investment Tracker, 150-151

Items collection in ListBox control, 160-161

List Box Builder, 154

ListboxChoice class, 159-160

program, 162

StockFactory class, 157

VB.NET creation of, 156-160

Building objects, 38-39

Buttn class, 333

Button class, 331

Buttons

behavior, 404-405

command objects, 410

decorating, 229

explaining operations of, 303-304

bVacationVisitor class, 452, 453

ByRef modifier, 60

ByVal modifier, 60

C

C#, 66

Caching results, 227

calcLaneOrder function, 115

calcValue method, 56

Callbacks and templates, 444

Caretaker class, 384, 387, 394

Caretaker object, 382

Catalog object, 259

Catch statement, 93

Catch-all operations with visitors, 454-455

CDate function, 64

CDbl function, 63, 64

Celsius temperature scale, 17-20

Chain class, 306, 314, 351

Chain interface, 309, 310, 351

Chain of Responsibility, 301, 303-304

command-interpreter program, 304-307

consequences of, 317

Help system, 310-312

inheritance, 317

Interpreter pattern, 348-353

linearity, 313

list boxes, 308-309

program, 318

tree structure, 313-314

types of requests, 316

usage, 304

VB examples, 316-317

VB.NET, 314-316

Check Box Builder, 154-155, 158

Checkbox type, 158

CheckChoice class, 158-159

Child nodes, 187-188, 212

CInt function, 63, 64, 177

Circle class, 405

Circle object, 406

Circle seeding, 113, 120

CircleButton class, 420

CircleSeeding class, 115, 118, 120

Class adapters, 183, 194-195

VB.NET, 195-196

Class keyword, 68

Class modules, 19

Classes, 19, 27

adding and removing at run time, 179

adding to Abstract Factory pattern, 136

ancillary, 57

circular references to other classes, 179

cloning, 166, 168, 179

concrete, 129

constructors, 30, 74-76

containment, 29-30

data, 38

deep copy, 168

derived, 7-8

dissimilar with same interface, 172-174

encapsulating error handling, 24-25

format and value conversion, 22-25

functions, 40

global point of access, 140

handling requests, 303-304

hierarchy representation, 14-15

holding data, 20

implementing interface, 86

inheritance, 7-8, 12-14, 78

initializing, 30, 73

inside of classes, 15

instances, 19, 27, 38

instantiating, 38

methods, 38

names, 12, 38, 68

naming, 35-36

naming instances, 36

New methods, 73

as objects, 27-30

only one accessible instance, 138

patterns, 181

properties, 30-32

shallow copy, 168

sharable instances, 279

shared methods, 143-144

subclasses, 13

traversing series of, 456

variables, 40-41

VB.NET, 67-68

visiting, 451-453

Classes and interfaces, 32-33

Class_Initialize event, 30, 137

Clear method, 47, 92, 371

ClearButton class, 376, 420

Clearing text boxes, 47

click event, 410

Click method, 71

Client object, 347

CLng function, 64

Clone method, 166

Cloning, 166, 168, 179

closeTriangle method, 444

.cls file extension, 39, 68

clsTemp class, 19-22

clsTemp class module, 19

cMain module, 69

cmdButton class, 334

cmdButton control, 331

cmdMenu class, 333, 334

CmdToolBarButton class, 420

Cocoon factory, 111-112

Colleague interface, 378

Colleagues, 369

Collection objects, 28, 91-93

ColorChain class, 307

ColorForm window, 397

ColorImage class, 309

Column object, 260

comClick method, 142

ComdHolder class, 334-335

Command class, 50

Command interface, 49-50, 321, 324, 326, 330, 331, 376, 420

Command objects, 258, 320-321, 332, 347, 384, 421

building, 321-322

buttons, 410

containers for, 333

mediator pattern, 373

Undo function, 326-330

in user interface, 389-390

Command pattern, 301

arrays of commands, 322-325

building command objects, 321-322

command objects, 320-321

CommandHolder interface, 332-335

consequences of, 325

motivation for use of, 319

program, 338

providing Undo function, 326-330

UndoCommand version, 335-338

VB.NET, 330-332

CommandHandler, 376

CommandHolder interface, 332-335

Command-interpreter program, 304-307

Commands

arrays of, 322-325

program, 338

queuing, 321

undoing, 326-330

Comments and UML diagrams, 15-16

commForm control, 143

CommonDialog object, 322

Communication patterns, 5

Compilers and VB.NET options, 63

Compiling user controls, 47

Components, constructing objects from, 149

Composite pattern, 211-212

Boss class, 216-218

building employee tree, 219-221

caching results, 227

computing salaries, 213

consequences of, 222-223

doubly linked lists, 221-222

employee classes, 213-215

Enumerator, 225

implementation, 212-221

multiple boss constructors, 226

ordering components, 227

program, 228

self-promotion, 221

SimpleComposite example, 223

Subords class, 215-216

VB.NET, 223-226

Composites, 181, 211-212, 239

program, 228

Composition, 14-15

Computing salaries, 213

Concrete classes, 129, 136

Concrete Factory class, 129, 130

Concrete methods, 439

ConcreteImplementors, 197

Connection object, 258-259, 260

Console application, 69

Console.WriteLine statement, 62

Constructors, 30

filename and path, 99

hello window, 73

overloading, 77

private, 144

VB.NET, 74-76

Containers, 223

Command object and, 333

Containment, 43

contains method, 92, 386

Context class, 425, 427-428

Context interface, 435

Context object, 347

ControlAdapter class, 187

ControlAdapter interface, 188

Controller, 4

Controls, 72

adding methods, 187

creation of, 236

declared as variable, 72

derived from Windows control, 331

event handling, 376-377

focus, 311

initialization, 375-376

interactions between, 369-370

modifying code for, 72

naming, 35

repainting, 76

Tooltips, 76

Controls collection, 223

Convert class, 64

Converting

formats, 22-25

to Kelvin, 20-21

values, 22-25

CoolButtons class, 232-233

CoolDecorator class, 230-232

Copy method, 371

CopyButton class, 376

CopyCommand class, 370

Copy-on-Write objects, 290-291, 298

CopyTo method, 92

count method, 157

count property, 212

CreateText method, 97

Creational patterns, 6, 103-104

CSng function, 63, 64

CStr function, 64

Ctype function, 158

Currency type, 64

Current property, 77

currentState variable, 408

Cursor class, 296

Cursor object, 77

Cursors, 77

D

Data, 38

conversions, 177

displaying in multiple forms, 395-396

extracting from databases, 243-244

loading, 207

manipulation, 18

moving between lists, 183-185

public or private modifier, 38-39

valid, 41

Data model, 3-4

Data representations of trees, 211

Database object, 245

Databases, 165, 241-243

ADO (ActiveX Data Objects), 245

ADO access, 256-264

connection strategies, 245

DataTable class, 192

extracting data from, 243-244

indexes, 241

MDAC (Microsoft Data Access Components), 245

ODBC (Object Database Connectivity), 244-245

prototype usage, 166-170

RDO (Remote Data Objects), 245

Recordset, 166

relationships between tables, 250

structure, 245-248

tables, 242, 245, 250

types, 244

VB.NET access, 264

DataColumns class, 192

DataGrid class, 196

DataGrid control, 192-193, 206

DataRow object, 264

DataSet object, 264

DataTable class, 192, 193

DataTable object, 264, 267

db variable, 258

DB/2, 244

dBase, 244

DBase class, 246-248, 256, 260-262, 268, 290

DBTable class, 256, 269-270, 272

DBTable interface, 250, 253

Decimal type, 64

Decorating

buttons, 229

CoolButton, 230-232

PictureBox, 230

Decorator class, 230

Decorator pattern, 181, 229, 298

ActiveX controls as decorators, 236

consequences of, 239

decorating CoolButton, 230-232

decorator usage, 232-235

program, 240

VB.NET, 236-238

Decorators, 229, 239

ActiveX controls as, 236

usage, 232-235

Deep copy, 168

Default namespace, 78

Delete method, 99

Deleting files, 33, 96

Derived classes, 7-8, 78, 84, 229

calling methods from, 55-56

overriding, 81-82

overriding methods, 81-82

Simple Factory pattern, 106-107

Design Patterns, 4, 7

Design patterns, 3-4, 103

acceptance, 6

behavioral, 6

creational, 6

defining, 5-6

discovery of, 6

internalization, 7

learning process, 6-7

Model-View-Controller framework, 3-4

reason for using, 7

recognition, 6-7

structural, 6

studying, 7

VB6, 8

VB.NET, 8

Visual Basic, 8

(The) Design Patterns Smalltalk Companion, 4

Design Patterns—Elements of Reusable Software, 4

Dim statement, 61, 63-64

new keyword, 19

VB.NET, 60

Director class, 151

DirectoryNotFoundException exception, 94

DivideByZeroException exception, 94

Dividing strings into tokens, 25-27

Double dispatching, 455

DoubleRect class, 81, 82

Doubly linked lists, 221-222

Draw method, 282

overloading, 82

draw method, 132, 329, 392, 419, 441, 442, 444, 448

draw2Line method, 441, 442, 444

drawCommand class, 329

drawData objects, 328

drawHandle method, 417

Drawing, 76

plots, 429-432

VB.NET, 76-77

Drawing class, 416

Drawing interface, 414, 417

drawLine method, 444

drawList collection, 328

drawRectangle method, 286

Dynamic arrays, 90

Dynamically changing forms, 152

E

Edit method, 245

elements method, 362

Employee class, 12-15, 213-215, 218, 221, 223-225, 449, 453, 456-457

Employee interface, 457

Employees class, 213

employees Collection, 223

EmployeeVisitor class, 455

Encapsulating error handling, 24-25

Encapsulation, 7, 8, 41, 43, 81, 189

EndIf keyword, 60

EndOfStreamException exception, 94

Enumerator, 225

Equities class, 156, 157

Equities interface, 152

Equity class, 53, 160, 161

Equity interface, 53, 54, 153

Error handling in Singleton pattern, 145-146

ET++, 4

Event object, querying, 71

EventFactory factory, 121

Events

Factory Method pattern, 121

handling for controls, 376-377

Events class, 113-115, 117-119, 121-122

Examplar pattern, 165

Exception handling, 93

Exceptions, 93-94, 145-146

file handling, 97

file input and output, 97

multiple, 94-95

throwing, 95

.EXE file, 47

Execute method, 50, 320, 330, 333, 411, 420-421, 434

ExecuteNonQuery method, 266

Exists method, 99

exit class, 321

ExitCommand class, 50, 334

ExitCommand object, 50

ExitMenu class, 331-332

Extending Bridge class, 202

Extension method, 99

External iterators, 365

External static variables, 137

Extracting data from databases, 243-244

F

Facade classes, 249-252

Facade pattern, 181, 241

ADO.NET, 264-268

consequences of, 276

elements, 276

Facade classes, 249-252

Foods table, 252-253

price query, 255

Price table, 253-255

Stores class, 250-252

Stores table, 252-253

usage, 256

VB7-style grocery database, 268-275

Facade program, 277

FacadeADO program, 277

Factor variable, 40

Factories, 103

Factory class, 151

Factory Method pattern, 103, 113

abstract classes, 113

circle seeding, 120

events, 121

Events class, 117-119

straight seeding, 119-120

subclasses, 113

Swimmer class, 117

uses for, 123

VB7 seeding program, 121-123

viewing seedings, 120

Factory pattern, 180

math computation, 111-112

program, 112, 124

Fahrenheit temperature scale, 17-20

FFT (Fast Fourier Transform), 111

Field object, 245

File class, 96, 99, 144, 166

File handling, 33-35, 95-97

File method, 95

File object, 96-97

File|Add project command, 45

File.AppendText method, 96

FileChain class, 315

FileCommand class, 334

File.Copy method, 96

File.Delete method, 96

File.Exists method, 96

File|Exit command, 319, 321, 330

File.getAttributes method, 96

FileInfo class, 98-99

FileList class, 309

File|Make Project Group command, 47

File.Move method, 96

File|New Project command, 43, 69

File|New project command, 70

FileNotFoundException exception, 94

File|Open command, 319, 322, 330

File.OpenText method, 96

File.OpenWrite method, 96

File|Red command, 319

Files

checking for existence of, 33

deleting, 33, 96

information about, 98-99, 144

input and output and exceptions, 97

manipulation code and try blocks, 97

opening, 33

program, 101

reading data from, 33

renaming, 33

FileStream object, 96

Fill class, 405, 407

fill method, 420

Fill State object, 412-413

FillButton class, 420

FillDataSet method, 265

FillMemento class, 415

Filtering iterators, 360-362

FinalImage class, 295, 296

First normal form (1NF), 242

FirstFirst class, 110

Float constant, 290

Flyweight classes, 282

Flyweight pattern, 181, 279-280

class diagram, 284

copy-on-write objects, 290-291

example code, 280-286

selecting folder, 284-286

sharable objects, 290

uses in VB, 290

VB.NET, 286-289

FlyweightFactory class, 280

program, 291

FNamer class, 106-107

Folder class, 286

FolderFactory class, 281-282, 283, 286

Folders

icons for, 280-286

selecting, 284-286

Food class, 270

Food table, 274

FoodKey, 250

FoodName, 250

Foods table, 250, 252-253, 272

Form class, 72

Form1.vb form project, 70

Format method, 63, 226

Formats, converting, 22-25

Form_Load event, 25, 121, 187, 233-234, 308, 371

Forms

control creation, 236

controls, 72

displaying data in multiple, 395-396

dynamically changing, 152

name order, 106

simple, 71

Form_Unload event, 321

FoxBase, 244

Friend classes, 86

friend keyword, 382, 391

.frm file extension, 39, 68

Functional libraries, 67

Functions, 40, 61

Funds class, 152

G

Gamma, Erich, 4

Gang of Four, 4

Garbage collection, 66-67

Garden class, 127, 131, 132

Garden interface, 128

Garden objects, 129

Gardener class, 134

GardenMaker Factory, 127-129, 130-131

GardenMaker window class, 133

Get functions, 40

Get method, 20, 65

Get property, 31

getAge method, 30, 167

getAvailablePorts method, 142

getBorder method, 132

getCels method, 20

getCenter method, 132

getChain method, 306

getChild method, 212, 215, 220, 223

getClass method, 106

getFahr method, 20

getFormatted accessor function, 23

getIterator method, 359

getJob method, 13-14

getKelvin function, 21

getLaneOrder function, 123

getName method, 167

getNames method, 157

getSalaries method, 213, 218, 225

getSeconds accessor function, 23

getSeeding method, 115, 117, 123

getSelected method, 154, 155

getShade method, 132

getSingle accessor function, 23

getSpooler method, 138, 145-146, 147

getSwimmer method, 167

getSwimmers method, 120

getTaxable method, 54

getTime method, 167

getVacDays function, 450

getValidPorts method, 142

getValue method, 213, 272

getWindow interface, 151

getXXX accessor functions, 28-29

GoF book, 4

GotFocus event, 45

Graphics, 76-77

Graphics object, 286, 392

GrassGarden class, 136

Grid adapter, 195

GridAdapter class, 192, 206

Groceries database, 264

H

Hashtables, 270, 392-393

count property, 92

Enumerator property, 271

key value, 91-92

hasMoreElements method, 216, 358, 361

Height method, 136

Hello window constructors, 73

Help (F1) key, 310

Help system, 303-304

Chain of Responsibility, 310-312

Hidden interfaces, 57

Highlighted text fields, 43-45

HiText User Control, 45-46

HiTextBox.vb object, 84

Hook methods, 439

HtextBox control, 85, 86

Hungarian notation, 35

I

Icon class, 296

IEnumerable interface, 225, 364

IEnumerator interface, 223, 225, 364

Image control, 294, 306

Image proxy, 294

ImageProxy class, 294, 297

Imager class, 309

Imager interface, 296

Imager object, 294

ImgChain class, 306

Implementor, 197

Imports statement, 67

Indexer class, 247, 256, 262-264

Indexes collection, 260

Indexes for databases, 241

indexOf method, 60-61, 92

IndexOutOfRangeException exception, 94

Indicators for using interfaces, 52-55

Inheritance, 7-8, 12-14, 41-42, 183

adding responsibilities with, 239

Chain of Responsibility, 317

classes, 78

program, 57

Simple Factory pattern, 109

VB.NET, 72-74, 78

Init method, 30, 50, 51, 74-75, 79-80

init method, 54, 207, 370, 373, 376, 386

In-memory data array, 192

Insert method, 92

Instances, 19, 27

intrinsic data, 279

naming, 36

TapeMeasure class, 38, 39

Instantiating classes, 38

Instr function, 26, 60-61

Integer constant, 290

Integers, 387

Interactions

between controls, 369-370

between objects, 5

Interator pattern

fetching iterator, 359-360

sample VB6 code, 358-360

Interfaces, 7-8, 14, 49-50

classes and, 32-33

converting into another interface, 183

definition, 49

deriving base, 136

dissimilar classes with same, 172-174

hidden, 57

implementing, 49

implementing methods, 86

indicators for using, 52-55

inheritance, 183

Iterator, 357

looking the same as class’s interface, 197

manipulation, 18

object composition, 183

public, 86

varying without changing implementation, 202

VB.NET, 85-86

Voltmeter program, 32-33

Internal iterators, 365

InterpChain class, 348, 350, 351

Interpreter pattern, 301, 339

Chain of Responsibility, 348-353

consequences, 354-355

flexibility, 347

implementing, 347-350

interpreting language, 341-342

motivation for using, 339

objects in parsing, 342-346

parsing objects, 353-354

reducing parsed stack, 346-347

report generator, 340-341

syntax tree, 348-350

VB6, 350-353

Interpreters, 339-340

Interpreting language, 341-342

Invalid port number error, 141, 142

Invest method, 51

Investment simulator, 50-52

Investment Tracker, 150-154

isBond method, 54

isCelsius Boolean, 22

IsNull method, 98

isUndo method, 328

Item method, 92

Items collection, 160-161, 189

Iterator interface, 358

Iterator pattern, 301

data modification, 364-365

external versus internal iterators, 365

filtering iterators, 360-362

motivation, 357-358

priviledged access, 365

program, 365

VB.NET, 363-364

Iterators, 357

fetching, 359-360

filtering, 360-362

J

j variable, 62

Jacobson, Ivar, 11

Java Design Patterns Java: A Tutorial, 4

K

Kelvin, converting to, 20-21

Key value, 91-92

Keyboard listeners, 311

KeyDown event, 311-312

kid variable, 361

kidClub class, 362

KidClubIterator class, 361, 363

KidData class, 358, 360, 361, 362

KidIterator class, 359, 364

KidList class, 360

KidListBox class, 376

Kids class, 359, 376

Kids object, 323

L

LastFirst class, 110

lastMeasure method, 41

lbHi label, 71

Leaf node, 212

Leaves, 211-212

Left function, 60-61

legalInstance variable, 138

Length method, 98-99

Let method, 65

Let property, 31

Line command, 430

Line Input statement, 95

LineCmd class, 428-429

LinePlot class, 437

LinePlotStrategy class, 429, 432

List adapter, 195

List Box Builder, 154

List boxes and Chain of Responsibility, 308-309

ListAdapter class, 189, 190

ListBox class, 188, 189, 194, 197, 200, 206, 308

ListBox control, 160-161

ListboxChoice class, 159-160

listBridge class, 199, 200, 201, 205

listener, 337

ListIndex property, 189

Lists, moving data between, 183-185

LNamer class, 107

Loading data, 207

M

Macro language recorders, 339

Main module, renaming, 69

MainMenu control, 331

makeBoss method, 226

makeCel method, 22

makeFahr method, 22

Managed languages, 66

Manager class, 454-455

ManagerVisitor class, 455

Math computation in Factory patterns, 111-112

MDAC (Microsoft Data Access Components), 245

MDAC package, 257

MDI forms, dynamically changing, 152

Measure.cls program, 38

Measure.frm classes, 38

Measurement program, 39-40

Measurer form, 40

Mediator class, 370, 386, 420

Mediator pattern, 301, 367

Colleagues, 369

command objects, 373

consequences, 377-378

example system, 367-368

handing events for controls, 376-377

implementation issues, 378

initialization, 375-376

initialization of system, 372-373

interactions between controls, 369-370

sample code, 370-373

VB.Net, 373-377

Mediators

god class and, 421-422

interacting with state manager, 409-411

single-interface, 378

Memento class, 386, 394, 416, 420

Memento interface, 413-414

Memento object, 382, 387, 413

Memento pattern, 301, 381

checking type of object, 389

command objects in user interface, 389-390

consequences, 394

handling mouse and paint events, 390-391

implementation, 382

motivation, 381-382

sample code, 382-389

VB.NET, 391-393

MenuItem class, 331, 333

MessageBox class, 144

Metafile class, 296

Methods, 12, 19, 37, 38, 40

adding to controls, 187

base class, 55

calling arguments, 77

concrete, 439

File class, 96

Hook, 439

inaccessible overloaded, 83

MustOverride, 439

nonshared, 144

overloading, 78

overriding in derived classes, 81-82

polymorphic, 77

private, 22, 38-39, 40, 81

protected, 81

public, 22, 38-39, 40, 81

registering as event handler, 332

reusing, 55-57

shared, 96

signatures, 77

static, 96

template, 439

types in Template class, 439

vbFile class, 34

minVal value, 25

mnuExit menu item, 319

mnuOpen menu item, 319

mnuRed menu item, 319

Model-View-Controller framework, 3-4

Module module, 68

Modules, 68-69

Mouse events, handling, 390-391

mouse move event handler, 288

MouseDown method, 417

MouseLeft event, 231

MouseMove event, 231, 316

mouse_over flag, 237

mouseUp event, 405

move method, 417

Moving data between lists, 183-185

MSComctlLib.Button class, 389

MSComm control as Singleton pattern, 140-143

MSFlexGrid control, 185-187, 197

MultiChoice factory, 161

MultiChoice interface, 156

multiChoice interface, 151

multiChoice windows, 152

Multiple boss constructors, 226

Multiple exceptions, 94-95

multiselect list box, 159-160

MultVar class, 346, 349

MustInherit keyword, 176, 314

MustOverride keyword, 13, 176, 314, 439

Mutuals class, 152, 153, 157

MyBase.New method, 74

N

Name method, 99

NameClass class, 109-110

Namer class, 109

Namespaces, 67-68

VB.NET, 78-80

.NET applications, 59

New constructor, 74, 144

New dialog box, 70

New keyword, 19

New method, 74, 178, 207

New methods, 78

nextElement method, 216, 361

Next-Token method, 26

nextTop method, 342

NoCmd class, 308

Node class, 223

Nodes, 211-212

Nodes collection, 187

Nonleaf node, 212

Nonshared methods, 144

NonTerminalExpression object, 347, 350

Nonvisual decorators, 239

Normal form, 242-243

Null Reference exception, 98

Null strings and length method, 98

NullReferenceException exception, 94

Numbers, 63-64

O

Object adapters, 183, 195

TreeView control, 188

VB.NET, 195-196

Object composition, 8, 183, 189

Object patterns, 181

Object type, 158

Object-oriented approaches, 7-8

Object-oriented code, reusing, 3

Object-oriented programming, 39-40

Object-oriented terminology, 41-42

Objects

building, 38-39

checking type, 389

classes as, 27-30

communicating, 4

constructing from components, 149

contained within other objects, 14-15

design, 5

forwarding request to specific, 319

inheritance, 41-42

instances, 38, 39, 103

interaction between, 5

methods, 37, 40

modifying behavior, 229

most suitable for action, 304

new at run time, 179

parsing, 342-346, 353-354

postponing creation, 293

represented as class modules, 38

representing relationships, 16

states, 38

storing state, 381-382

VB.NET, 63

Observer interface, 396, 399

Observer pattern, 301, 395-396

consequences, 401-402

notifying observers, 401

VB.NET, 399-400

watching colors change, 396-399

.OCX file, 47

ODBC (Object Database Connectivity), 244-245

OleDbCommand object, 264, 266

OleDbConnection object, 264

OleDbDataAdapter object, 264

OneSexSwimData class, 170-173

OnPaint event, 76, 79, 131, 236

OnPaint method, 80, 133

OpenMenu class, 331

OpenText method, 99

OpenWrite method, 99

Option Explicit directive, 63

Option Strict On statement, 63

Options dialog box, 139

Oracle, 244

Ordering components, 227

Originator class, 394

Originator object, 382

OurList class, 194

Output, varying kinds, 340

Overloading

constructors, 77

draw method, 82

methods, 78

setData methods, 83

shadowing, 83-84

OverLoads keyword, 77, 78

Overloads keyword, 224

Overriding

methods in derived classes, 81-82

onPaint event, 79

Windows controls, 84-85

P

Package name, 12

paint event, 390-391, 430

paint event handler, 287, 337

paint method, 133-134, 238, 433, 443

PaintEventArgs object, 76

Panel class, 156, 159, 161, 236

Paradox, 244

Parent node, 188

ParseObject class, 343, 353, 354

ParseObject interface, 353

Parser class, 344, 347, 350

ParseVar class, 343, 345, 353, 354

ParseVerb class, 343, 345, 353, 354

Parsing

algebraic strings, 340

objects, 342-346, 353-354

user commands, 340

Part-whole hierarchies, 211

Passing arguments by reference and value, 41

Pattern mining, 6

Peek method, 98

Pen object, 76

PerennialGarden class, 129

Person class, 11-15

Pick class, 405

PickButton class, 420

PickKids class, 324, 325

PictureBox control, 133-134, 433

decorating, 230

Image property, 296

PixtureBox, 232

Plant class, 131

Plant objects, 128, 129

plot method, 427, 430, 439

PlotPanel class, 439

PlotStrategy class, 426, 432

pluggable adapters, 196

Polymorphic methods, 77

Polymorphism, 41

pop method, 342

Port already open error, 141, 142

Prelim class, 122

PrelimEvent class, 114-115, 118, 120-121, 123

Price class, 250, 253, 255, 274

Price table, 250, 253-255, 274

PriceKey, 250

Prices class, 270, 272-273

Primitive elements, 212

Print class, 353

Print method, 144

Print object, 343

Printit class, 354

PrintSpooler class, 137

Private constructors, 144

Private methods, 22, 81

Private variables, 20, 81

Procedural programs, 39

Product class, 198

productList class, 201

ProductTable class, 200, 201, 206-207

Program objects, 320-321

Programming

object-oriented, 39-40

styles, 35-36

Programs

data manipulation, 18

interface manipulation, 18

procedural, 39

temperature conversion, 17-18

undo function, 326-330

Project|Add class module menu item, 19

Project|Add User Control command, 236

Project|Add User Control menu, 84

Project|Components command, 47

Project|References command, 257

Properties, 30-32

Properties command, 69

Properties window, 19

Property Get method, 30

Property Let method, 30

Property pages dialog, 67

PropertyChanged method, 47

Protected keyword, 81

Protected methods and variables, 81

Prototype class, 168

Prototype managers, 174-175

Prototype pattern, 104, 165, 180

additional methods in subclasses, 171-172

consequences of, 179

dissimilar classes with same interface, 172-174

prototype managers, 174-175

prototype usage, 166-170

usage, 170-174

VB7 creation of, 175-179

Prototypes, 165-170

Proxy pattern, 181, 293

comparing to related patterns, 298

Copy-on-Write, 298

sample code, 294-295

VB6, 298

VB.Net, 296-297

Public

interfaces, 86

methods, 22, 81

push method, 342

Q

Querying objects, 71

Queue object, 93

Queuing commands, 321

QuickImage class, 295, 296

R

RDO (Remote Data Objects), 245

Reading text files, 96, 99-100

Recordset object, 166, 245, 258, 259

Rect class, 405

Rectangle button, 382

Rectangle class, 78-80, 81, 284, 288, 386

Rectangle object, 392, 406

RectButton class, 390, 392, 420

RectState class, 417

RectState object, 406

RedButton class, 330-331

redButton class, 334

RedCommand class, 334

RedCommand object, 322

redCommand object, 328

ReDecorator class, 233-235

ReDim statement, 90-91

Reducing parsed stack, 346-347

Refined Abstraction, 197

Refresh method, 134

register method, 374

registerInterest method, 396

Remove method, 92

remove method, 215, 223

RemoveAt method, 92

Renaming

files, 33

Main module, 69

repaint method, 439

Repainting controls, 76

Repeating patterns, 5

Resize event, 45

Resizing

arrays, 90-91

Hitext User Control, 46

user controls, 45

RestList class, 309

restore method, 386, 388, 415

Reusing method, 55-57

Reusing object-oriented code, 3

Right function, 60-61

Rumbaugh, James, 11

Run (F5) keyboard shortcut, 69, 70

S

SayHello button and WithEvents modifier, 74

SayHello_Click subroutine, 74

Screen, updating, 131

Scripting.FileSystemObject object, 33

Second normal form (2NF), 242

Seeding class, 114-115, 121, 123

Select method, 371

SelectedIndex property, 189

selectOne method, 407

Sender class, 309

Sender object, 71

sendNotify method, 398, 399

sendToChain method, 306, 310, 315

Serial ports

access to, 140-143

listing available, 141, 142-143

status, 142

Set functions, 40

Set keyword, 19, 60

Set methods, 20

setAge method, 30

setBounds method, 429

setCels method, 20

setData method, 83-84

setFahr method, 20

setFill method, 417

setKelvin method, 21

setSelected method, 417

setSex method, 171-173

setSingle accessor function, 23

setText accessor function, 23

setUnits accessor function, 41

setXXX methods, 30

SexFrame class, 172

SexSwimData class, 170, 174

Shadowing and overloading, 83-84

Shadows keyword, 83, 84

Shallow copy, 168

Sharable objects, 290

Shared method, 96, 144, 157

Shared methods, 96, 143-144

Shared variables, 144

Shorthand equals syntax, 66

Signatures, 77

Simonyi, Charles, 35

Simple Factory pattern, 103

abstraction returning class, 109

building, 108-109

derived classes, 106-107

inheritance, 109

operation of, 105-106

sample code, 106

usage, 108-109

writing in VB.NET, 109-110

Simple forms, 71

Simple temperature conversion program, 17-18

SimpleComposite example, 223

Simplest window program, 70-72

Single-interface mediators, 378

Singleton classes, 140

Singleton pattern, 104, 137, 180

allowing small number of instances, 148

catching errors, 139

error handling, 145-146

global point of access, 140, 147

MSComm control as, 140-143

private constructors, 144

serial ports, 140

SpoolDemo program, 146

static method creation of, 137-139

VB.NET creation of, 143-146

Smalltalk and Model-View-Controller framework, 3-4

Smalltalk Companion, 4, 7

SolidBrush objects, 433

Solution Explorer window, 69

Sort class, 353, 354

sort function, 115, 123

Sort method, 92

sort method, 176, 178

Sort object, 343

sortBridge class, 202

SortedList class, 92

Sorting array a elements, 61-62

Split method, 25, 26, 75

spool_counter variable, 137

SpoolDemo program, 146

Spooler, 144

Spooler class, 144, 145

SpoolerException class, 145

SQL (Structured Query Language), 244, 266

SQL Server, 244

Square class, 79-80

Square from rectangle, 79-80

Stack class, 342

Stack object, 93

Startup module, 69

State class, 416-417

State interface, 407

State object, 405, 406

State pattern, 301, 403

consequences of, 422

Fill State object, 412-413

filling circles in VB6, 416

mediator interacting with state manager, 409-411

sample code, 403-408

state transitions, 422

switching between states, 408-409

undo list, 413-416

VB.NET, 416-421

StateManager class, 405, 408, 409, 420

States, 38

program, 423

switching between, 408-409

transitions, 422

Static methods, 12, 96, 137-139, 144

stdTriangle class, 441

Stock class, 52, 53-56

StockFactory class, 157

Stocks class, 152, 156

Store class, 270

Store table, 271, 274

StoreFoodPrice object, 272

StoreKey, 250

StoreName, 250

Stores class, 250-252

Stores table, 250, 252-253

Straight seeding, 113, 119-120

StraightSeeding class, 119, 120, 122-123

StraightSeeding subclass, 115

Strategy pattern, 301, 425

consequences of, 435

Context class, 427-428

drawing plots, 429-432

line and bar graph strategies, 429

motivation, 425-426

program commands, 428-429

sample code, 426-427

VB.NET, 432-435

Stream method, 95

Stream object, 98

StreamReader object, 96-97

StreamWriter object, 97

String class, 60, 75

String collection, 154

String constant, 290

String Tokenizer method, 77

Strings

arrays, 75

converting to numerical values, 63

dividing into tokens, 25-27

zero-based indexes, 61

StringTokenizer class, 73, 342, 344

strSd.seed method, 120

Structural patterns, 6, 181

Sub Main subroutine, 68

Subclasses, 13

Abstract Factory pattern, 136

additional methods in, 171-172

Factory Method pattern, 113

Subject interface, 396, 399

subordinates collection, 216

subordinates method, 215

Subords class, 215-216, 357

Subords collection, 217

Subroutines, arguments passed by value, 59-60

Substring method, 60-61

SwimData class, 167, 170, 172, 174, 175-176

SwimData interface, 171

Swimmer class, 28, 31, 117, 166, 167, 177

Swimmer object, 184, 190

Swimmer objects, 174

Swimmers class, 120

SwimmerTimes program, 31-32

Switching between states, 408-409

Sybase, 244

System namespace, 68

System.Drawing namespace, 78

T

Table object, 259

Tabledef object, 245

Tables, 242, 245, 250

first normal form (1NF), 242

normal form, 242-243

relationships between, 250

second normal form (2NF), 242

third normal form (3NF), 243

Tables collection, 260

TapeMeasure class, 38-41

tCallback method, 297

Temp variable

Temperature class, 19-22

Temperature conversion program, 17-18

Temperature variable, 20

Template class, 439

Template Method class, 439

Template Method pattern, 301, 437

consequences, 445

drawing isoseles triangle, 441-443

drawing standard triangle, 441

motivation, 437-439

sample code, 439-443

templates and callbacks, 444

triangle drawing program, 443

Template methods, 439

Templates, 437, 444

TerminalExpression object, 347, 350

Testing

for end of text files, 98

HiText User Control, 45-46

Text boxes, clearing, 47

Text fields, 43-45

Text files

opening, 97

reading, 96, 99-100

testing for end of, 98

writing, 97, 99-100

TextBox class, 43

Textbox class, 84

TextBox control, 85

Textbox control, 84

Third normal form (3NF), 243

Throw statement, 95

Throwing exceptions, 95

TimedFinal class, 122

TimedFinalEvent class, 114-115, 118, 120-122

TimerCallback class, 297

Times class, 29

TimeSwimData class, 174, 178

ToggleButton class, 382

Tokenizer class, 25-27, 30

ToolBarButton class, 420

Tools|Options command, 139

Tooltips, 76

top method, 342

toString method, 156, 160

Tree adapter, 195

TreeAdapter class, 187, 191-192

TreeNode class, 191

TreeNode collection, 191

TreeView adapters and VB.NET, 191-192

TreeView class, 191-192, 220, 223

TreeView control, 187-188

Triangle class, 439, 440-442, 444

TriangleForm class, 443

Try blocks, 93, 266

file manipulation code, 97

multiple exceptions, 94-95

Two-way adapters, 195

txEntry text box, 45

U

UML (Unified Modeling Language), 11

UML diagrams

abstract methods, 12

annotation, 15-16

basic, 11-12

class name, 12

comments, 15-16

composition, 14-15

inheritance, 12-14

interfaces, 14

methods, 12

package name, 12

representing object relationships, 16

static methods, 12

variables, 12

Undo button, 383

Undo command object, 237

Undo method, 388

unDo method, 328

UndoButton class, 392, 420

undoCommand object, 328

Undoing commands, 326-330

Unreasonable values, 24-25

Update method, 245, 259

Updating screen, 131

User controld

naming, 45

User controls, 43-45

adding properties and methods, 47

compiling, 47

resizing, 45

User errors, 139

User interfaces, 368

command objects, 389-390

controller, 4

data model, 3-4

GardenMaker Factory, 130-131

objects, 320-321

view, 4

UserControl canvas, 44

UserControl class, 84, 236, 331, 335-336

User-created namespaces, 78

V

VacationVisitor class, 453, 456

Val function, 20, 177

Value keyword, 65

Values

converting, 22-25

unreasonable, 24-25

VAR type, 343

Variables, 12, 38, 40-41

arrays, 90

assigning value, 61

declaring, 61-62, 78

external static, 137

initializing, 73, 78

length property, 90

passing arguments by reference and value, 41

private, 20, 40, 81

protected, 81

scope, 61-62

values of, 40

VB.NET, 76

Variant keyword, 60

Vars class, 346

VarVarParse class, 349, 352

VB6, 16

class name, 68

cloning, 166

design patterns, 8

properties, 65

visual builder (IDE) environment, 43

VB7. See VB.NET

VB7 GardenMaker program

PictureBox class, 133-134

RadioButton and Button events, 134

VB7-style grocery database, 268-275

classes for tables, 270-272

final application, 275

loading database tables, 274-275

storing prices, 272-273

VBA (Visual Basic for Applications), 339

vbFile class, 33-35, 99-100, 166, 177, 376

vbFile interface, 99

VB.NET, 16, 59, 66

arguments passed by value, 59-60

building applications, 69-70

calls to subroutines and methods, 59

class name, 68

classes, 67-68

compiler options, 63-64

constructors, 74-76

default project name, 70

design patterns, 8

Dim statement, 60

drawing, 76-77

graphics, 76-77

inheritance, 72-74, 78

interfaces, 88-86

namespaces, 78-88

numbers, 64

objects, 63

overloading, 77-78

properties, 65

returning value from function, 61

shorthand equals syntax, 66

simplest window program, 70-72

syntax differences, 59-61

TreeView adapters, 191-192

variable declarations and scoping, 61-62

variables, 76

VB.NET compiler, 64

vbObjectError constant, 139

VBPatterns namespace, 288

Verb class, 353

VERB type, 343

View, 4

visCircle class, 417, 419, 420

visit method, 448, 450-455

Visiting classes, 451-453

Visitor class, 448, 450, 452, 456

Visitor interface, 456

Visitor pattern, 301, 447

catch-all operations with visitors, 454-455

consequences, 459

double dispatching, 455

Employee and Boss visits, 453-454

motivation, 447-449

sample code, 449-451

traversing series of classes, 456

visiting classes, 451-453

writing visitor, 456-459

visList interface, 200-201, 205, 206

VisList object, 206

visRectangle class, 384, 386, 387, 391, 392, 417

Vistor class, 454

Visual Basic

case insensitivity, 35

design patterns, 8

programming styles, 35-36

project files, 16

Visual objects, overriding properties, 72

Visual Studio.NET, 69

Voltmeter program, 32-33

W

WateringFrequency method, 136

WebClass objects, 298

Wend keyword, 60

WildFlower class, 136

Windows Application, 70

Windows application buttons, 230

Windows controls, overriding, 84-85

Windows Designer, 70, 71

WindowsApplication1 application, 70

WithClass program, 16

WithEvents modifier, 74

Works, 244

Writing text files, 97, 99-100

X

X class, 106

XFactory class, 106

XY class, 106

XZ class, 106

Z

Zero-based arrays, 89, 91, 175

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