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Jon doesn’t just explain how C# works; he explains how the whole thing holds together as a unified design, and also points out when it doesn’t.
C# in Depth, Fourth Edition is your key to unlocking the powerful new features added to the language in C# 5, 6, and 7. Following the expert guidance of C# legend Jon Skeet, you'll master asynchronous functions, expression-bodied members, interpolated strings, tuples, and much more.
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About the Technology
The powerful, flexible C# programming language is the foundation of .NET development. Even after two decades of success, it's still getting better! Exciting new features in C# 6 and 7 make it easier than ever to take on big data applications, cloud-centric web development, and cross-platform software using .NET Core. There's never been a better time to learn C# in depth.
About the book
C# in Depth, Fourth Edition is a revised edition of the bestseller written by C# legend Jon Skeet. This authoritative and engaging guide is your key to unlocking this powerful language, including the new features of C# 6 and 7. In it, Jon introduces expression-bodied members, interpolated strings, pattern matching, and more. Real-world examples drive it all home. By the end of this awesome book, you'll be writing C# code with skill, style, and confidence.
Table of Contents takes you straight to the bookdetailed table of contents
Part 1: C# in context
1 Survival of the sharpest
1.1 An evolving language
1.1.1 A helpful type system at large and small scales
1.1.2 Ever more concise code
1.1.3 Simple data access with LINQ
1.1.4 Asynchrony
1.1.5 Balancing efficiency and complexity
1.1.6 Evolution at speed: using minor versions
1.2 An evolving platform
1.3 An evolving community
1.4 An evolving book
1.4.1 Mixed-level coverage
1.4.2 Examples using Noda Time
1.4.3 Terminology choices
Summary
Part 2: C# 2-5
2 C# 2
2.1 Generics
2.1.1 Introduction by example: collections before generics
2.1.2 Generics save the day
2.1.3 What can be generic?
2.1.4 Type inference for type arguments to methods
2.1.5 Type constraints
2.1.6 The default and typeof operators
2.1.7 Generic type initialization and state
2.2 Nullable value types
2.2.1 Aim: expressing an absence of information
2.2.2 CLR and Framework support: the Nullable<T> struct
2.2.3 Language support
2.3 Simplified delegate creation
2.3.1 Method group conversions
2.3.2 Anonymous methods
2.3.3 Delegate compatibility
2.4 Iterators
2.4.1 Introduction to iterators
2.4.2 Lazy execution
2.4.3 Evaluation of yield statements
2.4.4 The importance of being lazy
2.4.5 Evaluation of finally blocks
2.4.6 Implementation sketch
2.5 Minor features
2.5.1 Partial types
2.5.2 Static classes
2.5.3 Separate getter/setter access for properties
2.5.4 Namespace aliases
2.5.5 Pragma directives
2.5.6 Fixed-size buffers
2.5.7 InternalsVisibleTo
Summary
3 C# 3: LINQ and everything that comes with it
3.1 Automatically implemented properties
3.2 Implicit typing
3.2.1 Typing terminology
3.2.2 Implicitly typed local variables (var)
3.2.3 Implicitly typed arrays
3.3 Object and collection initializers
3.3.1 Introduction to object and collection initializers
3.3.2 Object initializers
3.3.3 Collection initializers
3.3.4 The benefits of single expressions for initialization
3.4 Anonymous types
3.4.1 Syntax and basic behavior
3.4.2 The compiler-generated type
3.4.3 Limitations
3.5 Lambda expressions
3.5.1 Lambda expression syntax
3.5.2 Capturing variables
3.5.3 Expression trees
3.6 Extension methods
3.6.1 Declaring an extension method
3.6.2 Invoking an extension method
3.6.3 Chaining method calls
3.7 Query expressions
3.7.1 Query expressions translate from C# to C#
3.7.2 Range variables and transparent identifiers
3.7.3 Deciding when to use which syntax for LINQ
3.8 The end result: LINQ
Summary
4 C# 4: improving interoperability
4.1 Dynamic typing
4.1.1 Introduction to dynamic typing
4.1.2 Dynamic behavior beyond reflection
4.1.3 A brief look behind the scenes
4.1.4 Limitations and surprises in dynamic typing
4.1.5 Usage suggestions
4.2 Optional parameters and named arguments
4.2.1 Parameters with default values, and arguments with names
4.2.2 Determining the meaning of a method call
4.2.3 Impact on versioning
4.3 COM interoperability improvements
4.3.1 Linking Primary Interop Assemblies
4.3.2 Optional parameters in COM
4.3.3 Named indexers
4.4 Generic variance
4.4.1 Simple examples of variance in action
4.4.2 Syntax for variance in interface and delegate declarations
4.4.3 Restrictions on using variance
4.4.4 Generic variance in practice
Summary
5 Writing asynchronous code
5.1 Introducing asynchronous functions
5.1.1 First encounters of the asynchronous kind
5.1.2 Breaking down the first example
5.2 Thinking about asynchrony
5.2.1 Fundamentals of asynchronous execution
5.2.2 Synchronization contexts
5.2.3 Modeling asynchronous methods
5.3 Async method declarations
5.3.1 Return types from async methods
5.3.2 Parameters in async methods
5.4 Await expressions
5.4.1 The awaitable pattern
5.4.2 Restrictions on await expressions
5.5 Wrapping of return values
5.6 Asynchronous method flow
5.6.1 What is awaited and when?
5.6.2 Evaluation of await expressions
5.6.3 The use of awaitable pattern members
5.6.4 Exception unwrapping
5.6.5 Method completion
5.7 Asynchronous anonymous functions
5.8 Custom task types in C# 7
5.8.1 The 99.9% case: ValueTask<TResult>
5.8.2 The 0.1% case: building your own custom task type
5.9 Async main methods in C# 7.1
5.10 Usage tips
5.10.1 Avoid context capture using ConfigureAwait (where appropriate)
5.10.2 Enable parallelism by starting multiple independent tasks
5.10.3 Avoid mixing synchronous and asynchronous code
5.10.4 Allow cancellation wherever possible
5.10.5 Testing asynchrony
Summary
6 Async implementation
6.1 Structure of the generated code
6.1.1 The stub method: preparation and taking the first step
6.1.2 Structure of the state machine
6.1.3 The MoveNext() method (high level)
6.1.4 The SetStateMachine method and the state machine boxing dance
6.2 A “simple” MoveNext() implementation
6.2.1 A full concrete example
6.2.2 MoveNext() method general structure
6.2.3 Zooming into an await expression
6.3 How control flow affects MoveNext()
6.3.1 Control flow between await expressions is simple
6.3.2 Awaiting within a loop
6.3.3 Awaiting within a try/finally block
6.4 Execution contexts and flow
6.5 Custom task types revisited
Summary
7 C# 5 bonus features
7.1 Capturing variables in foreach loops
7.2 Caller information attributes
7.2.1 Basic behavior
7.2.2 Logging
7.2.3 Simplifying INotifyPropertyChanged implementations
7.2.4 Corner cases of caller information attributes
7.2.5 Using caller information attributes with old versions of .NET
Summary
Part 3: C# 6
8 Super-sleek properties and expression-bodied members
8.1 A brief history of properties
8.2 Upgrades to automatically implemented properties
8.2.1 Read-only automatically implemented properties
8.2.2 Initializing automatically implemented properties
8.2.3 Automatically implemented properties in structs
8.3 Expression-bodied members
8.3.1 Even simpler read-only computed properties
8.3.2 Expression-bodied methods, indexers and operators
8.3.3 Restrictions on expression-bodied members in C# 6
8.3.4 Guidelines for using expression-bodied members
Summary
9 Stringy features
9.1 A recap on string formatting in .NET
9.1.1 Simple string formatting
9.1.2 Custom formatting with format strings
9.1.3 Localization
9.2 Introducing interpolated string literals
9.2.1 Simple interpolation
9.2.2 Format strings in interpolated string literals
9.2.3 Interpolated verbatim string literals
9.2.4 Compiler handling of interpolated string literals (part 1)
9.3 Localization using FormattableString
9.3.1 Compiler handling of interpolated string literals (part 2)
9.3.2 Formatting a FormattableString in a specific culture
9.3.3 Other uses for FormattableString
9.3.4 Using FormattableString with older versions of .NET
9.4 Uses, guidelines and limitations
9.4.1 Developers and machines, but maybe not end users
9.4.2 Hard limitations of interpolated string literals
9.4.3 When you can, but really shouldn’t
9.5 Accessing identifiers with nameof
9.5.1 Common uses of nameof
9.5.2 Tricks and traps when using nameof
Summary
10 A smörgåsbord of features for concise code
10.1 Using static directives
10.1.1 Importing static members
10.1.2 Extension methods and using static
10.2 Object and collection initializer enhancements
10.2.1 Indexers in object initializers
10.2.2 Using extension methods in collection initializers
10.2.3 Test code vs production code
10.3 The null conditional operator
10.3.1 Simple and safe property dereferencing
10.3.2 The null conditional operator in more detail
10.3.3 Handling Boolean comparisons
10.3.4 Indexers and the null conditional operator
10.3.5 Working effectively with the null conditional operator
10.3.6 Limitations of the null conditional operator
10.4 Exception filters
10.4.1 Syntax and semantics of exception filters
10.4.2 Retrying operations
10.4.3 Logging as a side-effect
10.4.4 Individual, case-specific exception filters
10.4.5 Why not just throw?
Summary
Part 4: C# 7 and beyond
11 Composition using tuples
11.1 Introduction to tuples
11.2 Tuple literals and tuple types
11.2.1 Syntax
11.2.2 Inferred element names for tuple literals (C# 7.1)
11.2.3 Tuples as bags of variables
11.3 Tuple types and conversions
11.3.1 Types of tuple literals
11.3.2 Conversions from tuple literals to tuple types
11.3.3 Conversions between tuple types
11.3.4 Uses of conversions
11.3.5 Element name checking in inheritance
11.3.6 Equality and inequality operators (C# 7.3)
11.4 Tuples in the CLR
11.4.1 Introducing System.ValueTuple<…>
11.4.2 Element name handling
11.4.3 Tuple conversion implementations
11.4.4 String representations of tuples
11.4.5 Regular equality and ordering comparisons
11.4.6 Structural equality and ordering comparisons
11.4.7 Womples and large tuples
11.4.8 The non-generic ValueTuple struct
11.4.9 Extension methods
11.5 Alternatives to tuples
11.5.1 System.Tuple<…>
11.5.2 Anonymous types
11.5.3 Named types
11.6 Uses and recommendations
11.6.1 Non-public APIs and easily-changed code
11.6.2 Local variables
11.6.3 Fields
11.6.4 Tuples and dynamic don’t play together nicely
Summary
12 Deconstruction and pattern matching
12.1 Deconstruction of tuples
12.1.1 Deconstruction to new variables
12.1.2 Deconstruction assignments to existing variables and properties
12.1.3 Details of tuple literal deconstruction
12.2 Deconstruction of non-tuple types
12.2.1 Instance deconstruction methods
12.2.2 Extension deconstruction methods and overloading
12.2.3 Compiler handling of Deconstruct calls
12.3 Introduction to pattern matching
12.4 Patterns available in C# 7.0
12.4.1 Constant patterns
12.4.2 Type patterns
12.4.3 The var pattern
12.5 Using patterns with the is operator
12.6 Using patterns with switch statements
12.6.1 Guard clauses
12.6.2 Pattern variable scope for case labels
12.6.3 Evaluation order of pattern-based switch statements
12.7 Thoughts on usage
12.7.1 Spotting deconstruction opportunities
12.7.2 Spotting pattern matching opportunities
Summary
13 Improving efficiency with more pass by reference
13.1 Recap: what do we know about ref?
13.2 Ref locals and ref returns
13.2.1 Ref locals
13.2.2 Ref return
13.2.3 The conditional ?: operator and ref values (C# 7.2)
13.2.4 Ref readonly (C# 7.2)
13.3 in parameters (C# 7.2)
13.3.1 Compatibility considerations
13.3.2 The surprising mutability of in parameters: external changes
13.3.3 Overloading with in parameters
13.3.4 Guidance for in parameters
13.4 Declaring structs as readonly (C# 7.2)
13.4.1 Background: implicit copying with read-only variables
13.4.2 The readonly modifier for structs
13.4.3 XML serialization is implicitly read-write
13.5 Extension methods with ref or in parameters (C# 7.2)
13.5.1 Using ref/in parameters in extension methods to avoid copying
13.5.2 Restrictions on ref and in extension methods
13.6 Ref-like structs (C# 7.2)
13.6.1 Rules for ref-like structs
13.6.2 Span<T> and stackalloc
13.6.3 IL representation of ref-like structs
Summary
14 Concise code in C# 7
14.1 Local methods
14.1.1 Variable access within local methods
14.1.2 Local method implementations
14.1.3 Usage guidelines
14.2 Out variables
14.2.1 Inline variable declarations for out parameters
14.2.2 Restrictions lifted in 7.3 for out variables and pattern variables
14.3 Improvements to numeric literals
14.3.1 Binary integer literals
14.3.2 Underscore separators
14.4 Throw expressions
14.5 Default literals (C# 7.1)
14.5.1 Default literals and optional parameters
14.6 Non-trailing named arguments (C# 7.2)
14.7 Minor improvements in C# 7.3
14.7.1 Generic type constraints
14.7.2 Overload resolution improvements
14.7.3 Attributes for fields backing automatically implemented properties
Summary
15 C# 8 and beyond
15.1 Nullable reference types
15.1.1 What problem do nullable reference types solve?
15.1.2 Changing the meaning when using reference types
15.1.3 Enter nullable reference types
15.1.4 Nullable reference types at compile time and execution time
15.1.5 The “damn it” or “bang” operator
15.1.6 Experiences of nullable reference type migration
15.1.7 Future improvements
15.2 Switch expressions
15.3 Recursive pattern matching
15.3.1 Matching properties in patterns
15.3.2 Deconstruction patterns
15.3.3 Omitting types from patterns
15.4 Indexes and ranges
15.5 More async integration
15.5.1 Asynchronous resource disposal with “using await”
15.5.2 Asynchronous iteration with “foreach await”
15.5.3 Asynchronous iterators
15.6 Features not yet in preview
15.6.1 Default interface methods
15.6.2 Record types
15.6.3 Even more features in brief
15.7 Getting involved
Conclusion
Appendixes
Appendix A: Language features by version
A.1 C# 2
A.2 C# 3
A.3 C# 4
A.4 C# 5
A.5 C# 6
A.6 C# 7.0
A.7 C# 7.1
A.8 C# 7.2
A.9 C# 7.3
What's inside
- Comprehensive coverage of C# 6 and 7
- Greatest hits of C# 2–5
- Extended pass-by-reference functionality
- String interpolation
- Composition with tuples
- Decomposition and pattern matching
About the author
Jon Skeet is a senior software engineer at Google. He studied mathematics and computer science at Cambridge, is a recognized authority in Java and C#, and maintains the position of top contributor to Stack Overflow.
We interviewed Jon as a part of our Six Questions series. Check it out here.
