C# in Depth

528 Pages·2019·5.03 MB·English

by  Jon Skeet

IN DEPTH
FOURTH EDITION
Jon Skeet
F E L
OREWORD BY RIC IPPERT
M A N N I N G
Praise for the Third Edition
“A must-have book that every .NET developer should read at least once.”
—Dror Helper, Software Architect, Better Place
“C# in Depth is the best source for learning C# language features.”
—Andy Kirsch, Software Architect, Venga
“Took my C# knowledge to the next level.”
—Dustin Laine, Owner, Code Harvest
“This book was quite an eye-opener to an interesting programming language that I have been
unjustly ignoring until now.”
—Ivan Todorovic´, Senior Software Developer
AudatexGmbH, Switzerland
“Easily the best C# reference I’ve found.”
—Jon Parish, Software Engineer, Datasift
“Highly recommend this book to C# developers who want to take their knowledge to pro
status.”
—D. Jay, Amazon reviewer
Praise for the Second Edition
“If you are looking to master C# then this book is a must-read.”
—Tyson S. Maxwell, Sr. Software Engineer, Raytheon
“We’re betting that this will be the best C# 4.0 book out there.”
—Nikander Bruggeman and Margriet Bruggeman
.NET consultants, Lois & Clark IT Services
“A useful and engaging insight into the evolution of C# 4.”
—Joe Albahari, Author of LINQPad and C# 4.0 in a Nutshell
“This book should be required reading for all professional C# developers.”
—Stuart Caborn, Senior Developer, BNP Paribas
ii
“A highly focused, master-level resource on language updates across all major C# releases. This
book is a must-have for the expert developer wanting to stay current with new features of the C#
language.”
—Sean Reilly, Programmer/Analyst Point2 Technologies
“Why read the basics over and over again? Jon focuses on the chewy, new stuff!”
—Keith Hill, Software Architect, Agilent Technologies
“Everything you didn’t realize you needed to know about C#.”
—Jared Parsons, Senior Software Development Engineer, Microsoft
Praise for the First Edition
“Simply put, C# in Depth is perhaps the best computer book I’ve read.”
—Craig Pelkie, Author, System iNetwork
“I have been developing in C# from the very beginning and this book had some nice surprises
even for me. I was especially impressed with the excellent coverage of delegates, anonymous
methods, covariance and contravariance. Even if you are a seasoned developer, C# in Depth
will teach you something new about the C# language.... This book truly has depth that no
other C# language book can touch.”
—Adam J. Wolf, Southeast Valley .NET User Group
“This book wraps up the author’s great knowledge of the inner workings of C# and hands it
over to readers in a well-written, concise, usable book.”
—Jim Holmes, Author of Windows Developer Power Tools
“Every term is used appropriately and in the right context, every example is spot-on and con-
tains the least amount of code that shows the full extent of the feature...this is a rare treat.”
—Franck Jeannin, Amazon UK reviewer
“If you have developed using C# for several years now, and would like to know the internals,
this book is absolutely right for you.”
—Golo Roden
Author, Speaker, and Trainer for .NET and related technologies
“The best C# book I’ve ever read.”
—Chris Mullins, C# MVP
C# in Depth
FOURTH EDITION
JON SKEET
FOREWORD BY ERIC LIPPERT
MANNING
SHELTER ISLAND
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This book is dedicated to equality, which is significantly harder to achieve in the real
world than overriding Equals() and GetHashCode().
vi
contents
foreword xvii
preface xix
acknowledgments xx
about this book xxii
about the author xxvi
about the cover illustration xxvii
PART 1 C# IN CONTEXT ............................................... 1
1 Survival of the sharpest 3
1.1 An evolving language 3
A helpful type system at large and small scales 4 ■ Ever more
concise code 6 ■ Simple data access with LINQ 9
Asynchrony 10 ■ Balancing efficiency and complexity 11
Evolution at speed: Using minor versions 12
1.2 An evolving platform 13
1.3 An evolving community 14
1.4 An evolving book 15
Mixed-level coverage 16 ■ Examples using Noda Time 16
Terminology choices 17
vii
viii CONTENTS
PART 2 C# 2–5 .......................................................... 19
2 C# 2 21
2.1 Generics 22
Introduction by example: Collections before generics 22
Generics save the day 25 ■ What can be generic? 29
Type inference for type arguments to methods 30 ■ Type
constraints 32 ■ The default and typeof operators 34
Generic type initialization and state 37
2.2 Nullable value types 38
Aim: Expressing an absence of information 39 ■ CLR and
framework support: The Nullable<T> struct 40 ■ Language
support 43
2.3 Simplified delegate creation 49
Method group conversions 50 ■ Anonymous methods 50
Delegate compatibility 52
2.4 Iterators 53
Introduction to iterators 54 ■ Lazy execution 55 ■ Evaluation
of yield statements 56 ■ The importance of being lazy 57
Evaluation of finally blocks 58 ■ The importance of finally
handling 61 ■ Implementation sketch 62
2.5 Minor features 66
Partial types 67 ■ Static classes 69 ■ Separate getter/setter
access for properties 69 ■ Namespace aliases 70
Pragma directives 72 ■ Fixed-size buffers 73
InternalsVisibleTo 73
3 C# 3: LINQ and everything that comes with it 75
3.1 Automatically implemented properties 76
3.2 Implicit typing 77
Typing terminology 77 ■ Implicitly typed local variables
(var) 78 ■ Implicitly typed arrays 79
3.3 Object and collection initializers 81
Introduction to object and collection initializers 81
Object initializers 83 ■ Collection initializers 84
The benefits of single expressions for initialization 86
3.4 Anonymous types 86
Syntax and basic behavior 86 ■ The compiler-generated
type 89 ■ Limitations 90
CONTENTS ix
3.5 Lambda expressions 91
Lambda expression syntax 92 ■ Capturing variables 94
Expression trees 101
3.6 Extension methods 103
Declaring an extension method 103 ■ Invoking an extension
method 104 ■ Chaining method calls 106
3.7 Query expressions 107
Query expressions translate from C# to C# 108 ■ Range
variables and transparent identifiers 108 ■ Deciding when
to use which syntax for LINQ 110
3.8 The end result: LINQ 111
4 C# 4: Improving interoperability 113
4.1 Dynamic typing 114
Introduction to dynamic typing 114 ■ Dynamic behavior
beyond reflection 119 ■ A brief look behind the scenes 124
Limitations and surprises in dynamic typing 127 ■ Usage
suggestions 131
4.2 Optional parameters and named arguments 133
Parameters with default values and arguments with names 134
Determining the meaning of a method call 135 ■ Impact on
versioning 137
4.3 COM interoperability improvements 138
Linking primary interop assemblies 139 ■ Optional parameters
in COM 140 ■ Named indexers 142
4.4 Generic variance 143
Simple examples of variance in action 143 ■ Syntax for
variance in interface and delegate declarations 144
Restrictions on using variance 145 ■ Generic variance in
practice 147
5 Writing asynchronous code 150
5.1 Introducing asynchronous functions 152
First encounters of the asynchronous kind 152 ■ Breaking
down the first example 154
5.2 Thinking about asynchrony 155
Fundamentals of asynchronous execution 155 ■ Synchronization
contexts 157 ■ Modeling asynchronous methods 158