How to Code .NET

231 Pages·2006·1.564 MB·English

by  Christian Gross

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BOOKS FOR PROFESSIONALS BY PROFESSIONALS® THE EXPERT’S VOICE® IN.NET
Companion
eBook
Author of
How to Code .NET: Tips and Tricks for Coding Available
Ajax Patterns
and Best Practices .NET 1.1 and .NET 2.0 Applications Effectively
Ajax and REST Recipes:A
H
Problem-Solution Approach
Dear Reader,
Foundations of Object-
Oriented Programming Like you, I am a coder, architect, and developer. People who are coders, archi- o How to
Using .NET 2.0 Patterns tects, or developers strive to do their best, and if given the choice they will
always do something correctly. Of course, this begs the question: Why do we w
have so many bugs in our code?
I think the main reason for buggy code is that we are all short on time. We
don’t have the luxury of investigating new Framework features fully or exploring
innovative new techniques as thoroughly as we would like, because we’re all t
watching the clock. That means our code has bugs—the new Framework feature
o
we implemented doesn’t work quite as expected, and the new best practice we
Code .NET
put in place doesn’t seem to work the same way for every input. These bugs are

frustrating and can often be very difficult to solve.
C
This book is a response to that problem. In it I have investigated and recorded
my experiences of a wide range of .NET Framework features. They’re arranged
in simple, bite-sized sections dedicated to problem solving, informing you of o
little-known functionality and keeping you up to date with the latest design
thinking. It’s a road map to your more effective use of the .NET Framework. d
For example, the .NET Framework 2.0 introduced the yield keyword. On the
face of it, this is a really cool new piece of functionality that we’d all like to use.
e
But what’s it really like? Is it buggy? Is it going to be the future of all iterators?
This book digs into these questions and more to provide you with the answers Tips and Tricks for Coding .NET 1.1
that you need.
.
Christian Gross N
and .NET 2.0 Applications Effectively
E
T
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7443FM.qxd 9/21/06 10:46 PM Page i
How to Code .NET
Tips and Tricks for Coding
.NET 1.1 and .NET 2.0
Applications Effectively
Christian Gross
7443FM.qxd 9/21/06 10:46 PM Page ii
How to Code .NET: Tips and Tricks for Coding .NET 1.1 and .NET 2.0 Applications Effectively
Copyright © 2006 by Christian Gross
All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means,
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ISBN-13 (pbk): 978-1-59059-744-6
ISBN-10 (pbk): 1-59059-744-3
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Contents at a Glance
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
■ CHAPTER 1 Testing Your Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
■ CHAPTER 2 .NET Runtime- and Framework-Related Solutions . . . . . . . 31
■ CHAPTER 3 Text-Related Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
■ CHAPTER 4 C# Coding Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
■ INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
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Contents
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
About the Technical Reviewer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
■ CHAPTER 1 Testing Your Code. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Quick Notes About TDD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Getting Started with TDD and NUnit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Writing Tests Using Contexts and Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Writing Tests for Code Pieces That Have No Tests or Few Tests. . . . . . . . 11
Writing Tests for Code Pieces That Don’t Give Information Back . . . . . . . 19
Verifying the Correctness of an Object Instance
Without Having Access . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
■ CHAPTER 2 .NET Runtime- and Framework-Related Solutions . . . . . . . 31
Keeping Value Types and Reference Types Straight . . . . . . . . . . . . . . . . . . 31
Using Delegates. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Versioning Assemblies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Loading and Unloading Assemblies Dynamically. . . . . . . . . . . . . . . . . . . . . 47
Loading Assemblies Dynamically . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Loading and Unloading Assemblies Dynamically. . . . . . . . . . . . . . . . 52
Implementing GetHashCode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Thinking of .NET Generics as Black Boxes. . . . . . . . . . . . . . . . . . . . . . . . . . 72
Figuring Out What Generic Methods Do. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
Using the new and class Keywords with .NET Generics. . . . . . . . . . . . . . . 82
■ CHAPTER 3 Text-Related Solutions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Converting a String to an Array and Vice Versa . . . . . . . . . . . . . . . . . . . . . . 85
Parsing Numbers from Buffers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
Processing Plain-Vanilla Numbers in Different Cultures. . . . . . . . . . 89
Managing the Culture Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
v
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vi ■ CONTENTS
When to Use StringBuilder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
Finding a Piece of Text Within a Text Buffer . . . . . . . . . . . . . . . . . . . . . . . . 101
Always Implement ToString. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
Using a Disposable Type to Find Multiple Text
Pieces and Iterate the Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
Making ToString Generate Structured Output. . . . . . . . . . . . . . . . . . . . . . . 110
■ CHAPTER 4 C# Coding Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
What Does the Yield Keyword Really Generate? . . . . . . . . . . . . . . . . . . . . 117
Using Inheritance Effectively. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Implementing Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Naming Conventions for a Namespace,a Class,and an Interface. . . . . 135
Namespaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
Class and Interface Identifiers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
Understanding the Overloaded Return Type and Property. . . . . . . . . . . . 139
Nullable Types:A Null Is Not Always a Null. . . . . . . . . . . . . . . . . . . . . . . . . 145
Abstract-Class Bridge-Pattern Variation . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
Nested Private-Class Bridge-Pattern Variation. . . . . . . . . . . . . . . . . . . . . . 151
Dealing with Marker Interfaces or Base Classes. . . . . . . . . . . . . . . . . . . . 153
Editing Text Using the Command Pattern. . . . . . . . . . . . . . . . . . . . . . 154
Marker Interfaces and Their Dependencies . . . . . . . . . . . . . . . . . . . 156
How Marker Interfaces Dependencies Are Implemented. . . . . . . . 157
A Null Value Is Not Always a Null State . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165
The Essentials of the Factory Pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
The Classical Factory Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170
More Sophisticated Factory Implementations . . . . . . . . . . . . . . . . . 173
Don’t Expose a Class’s Internal State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Designing Consistent Classes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Immutable Types Are Scalable Types. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187
Understanding and Using Functors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191
The Comparer Functor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
The Closure Functor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
The Predicate Functor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
The Transformer Functor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Functors in Practice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
Avoiding Parameters That Have No Identity . . . . . . . . . . . . . . . . . . . . . . . . 205
■ INDEX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 209
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About the Author
Many people say that by looking at a person’s dog, you can tell what
the person is like. Well, the picture of me is my dog Louys, an English
Bulldog. And yes, my English Bulldog and I have many common
characteristics.
But what about my biography? It’s pretty simple: I am guy
who has spent oodles of time strapped to a chair debugging and
taking apart code. In fact, I really enjoy this business we call software development. I have
ever since I learned how to peek and poke my first bytes. I have written various books,
including Ajax and REST Recipes:A Problem-Solution Approach, Foundations of Object-
Oriented Programming Using .NET 2.0 Patterns, and A Programmer’s Introduction to
Windows DNA, all available from Apress.
These days I enjoy coding and experimenting with .NET, as it is a fascinating environ-
ment. .NET makes me feel like a kid opening a present on Christmas morning. You had an idea
what the gift was, but you were not completely sure. And with .NET there is no relative giving
you socks or a sweater. It’s excitement all the way!
vii
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About the Technical Reviewer
■ JASON LEFEBVREis vice president and founding partner of Intensity Software, Inc.
(http://www.intensitysoftware.com), which specializes in providing custom Microsoft .NET
applications, IT consulting services, legacy system migration, and boxed software products to
a rapidly growing set of clients. Jason has been using Microsoft .NET since its Alpha stages in
early 2000 and uses Visual Studio and the Microsoft .NET Framework daily while creating
solutions for Intensity Software’s clients. Jason has been a participating author for a number of
books and has written numerous articles about Microsoft .NET-related topics.
ix