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Programming with C++20 - Concepts, Coroutines, Ranges, and more


Foreword

Programming with C++20 teaches programmers with C++ experience the new features of C++20 and how to apply them. It does so by assuming C++11 knowledge. Elements of the Standards between C++11 and C++20 will be briefly introduced, if necessary. However, the focus is on teaching the elements of C++20.

You will start with learning about the so-called big four Concepts, Coroutines, std::ranges, and modules. The big four a followed by smaller yet not less important features. Here you will learn about std::format, the new way to format a string in C++. C++20 added a new operator, the so-called spaceship operator, which makes you write less code you will learn about in chapter 6. You then will look at various improvements of the language, ensuring more consistency and reducing surprises. You will learn about how lambdas improved in C++20 and what new elements you can now pass to non-type template parameters. Because the STL is a big part of C++, you will learn about some improvement highlights there. Of course, you will not end this book without learning about what happened in the constexpr-world.

Stuttgart, January 2021

Andreas Fertig

Status

I finished writing all chapters on Oct. 13th. See my post for more details: Book: Programming with C++20 - Writing finished.

ToC

This is how the final table of contents most likely will look like (unless your feedback leads to a change):

  • 1 Concepts: Predicates for strongly typed generic code
    • 1.1 Programming before Concepts
      • 1.1.1 The enable_if requirement
      • 1.1.2 Long error messages from template errors
    • 1.2 What are Concepts
      • 1.2.1 Thinking in concepts
      • 1.2.2 Concepts and types
    • 1.3 The anatomy of a concept
    • 1.4 Existing Concepts
    • 1.5 The requires-clause: The runway for Concepts
    • 1.6 The requires-expression
      • 1.6.1 Simple requirement
      • 1.6.2 Nested requirement
      • 1.6.3 Compound requirement
      • 1.6.4 Type requirement
      • 1.6.5 Complete constrained version of add
    • 1.7 Adding Concepts to make requirements reusable
    • 1.8 Testing requirements
    • 1.9 Using a Concept
      • 1.9.1 Using a constexpr function in a concept
      • 1.9.2 Applying a concept with a requires-clause
      • 1.9.3 Applying a concept with a trailing requires-clause
      • 1.9.4 Applying a concept as a type-constraint
    • 1.10 Abbreviated function template with auto as generic parameter
      • 1.10.1 What does such a construct do?
      • 1.10.2 Exemplary use case: Requiring a parameter type to be an invocable
    • 1.11 Concepts and constrained auto types
      • 1.11.1 Constrained auto variables
      • 1.11.2 Constrained auto return-type
    • 1.12 The power of Concepts: requires instead of enable_if
      • 1.12.1 Call method based in requires
      • 1.12.2 Conditional copy operations
      • 1.12.3 Conditional destructor
      • 1.12.4 Conditional methods
    • 1.13 Concepts ordering
      • 1.13.1 Subsumption rules details
      • 1.13.2 One more thing, never say not
    • 1.14 Improved error message
  • 2 Coroutines
    • 2.1 Regular functions and their control flow
    • 2.2 What are Coroutines
      • 2.2.1 Generating a sequence with coroutines
    • 2.3 The elements of Coroutines in C++
      • 2.3.1 Stackless Coroutines in C++
      • 2.3.2 The new kids on the block: co_await, co_return and co_yield
      • 2.3.3 The generator
      • 2.3.4 The promise_type
      • 2.3.5 An iterator for generator
      • 2.3.6 Coroutine customization points
      • 2.3.7 Coroutines restrictions
    • 2.4 Writing a byte-stream parser the old way
    • 2.5 A byte-stream parser with Coroutines
      • 2.5.1 Writing the Parse function as coroutine
      • 2.5.2 Creating an Awaitable type
      • 2.5.3 A more flexible promise_type
      • 2.5.4 Another generator the FSM
      • 2.5.5 Simulating a network byte stream
      • 2.5.6 Plugging the pieces together
    • 2.6 A different strategy of the Parse generator
    • 2.7 Using a coroutine with custom new / delete
    • 2.8 Using a coroutine with a custom allocator
    • 2.9 Exceptions in coroutines
  • 3 Ranges: The next generation STL
    • 3.1 Motivation
      • 3.1.1 Avoid code duplication
      • 3.1.2 Consistency
      • 3.1.3 Safety
      • 3.1.4 Composability
    • 3.2 The who is who of ranges
    • 3.3 A range
      • 3.3.1 What is a common_range?
      • 3.3.2 A sized_range
    • 3.4 A range algorithm
      • 3.4.1 Projections for range algorithms
    • 3.5 A view into a range
    • 3.6 A range adaptor
      • 3.6.1 A custom range adaptor
    • 3.7 The new ranges namespaces
    • 3.8 Ranges Concepts
    • 3.9 Views
    • 3.10 Creating a custom range
      • 3.10.1 Implementing the view
      • 3.10.2 A range adaptor for custom_take_view
      • 3.10.3 Add the pipe-syntax to custom_take_view
      • 3.10.4 A more generalized pipe-syntax implementation
  • 4 Modules
    • 4.1 Background about why modules
      • 4.1.1 The include hell
      • 4.1.2 I like to have secrets
    • 4.2 Creating modules
      • 4.2.1 A header unit
      • 4.2.2 A named module
    • 4.3 Applying modules to an existing code base
      • 4.3.1 Down with namespace details
      • 4.3.2 Now I can hide my secrets from you...
      • 4.3.3 What you gain
      • 4.3.4 Templates in modules
      • 4.3.5 Down with DEBUG
      • 4.3.6 In-line definitions of class members
      • 4.3.7 There are some limits
  • 5 std::format: Modern & type-safe text formatting
    • 5.1 Formatting a string before C++20
      • 5.1.1 Formatting a stock index with iostreams
      • 5.1.2 Formatting a stock index with printf
    • 5.2 Formatting a string using std::format
      • 5.2.1 std::format specifiers
      • 5.2.2 Escaping
      • 5.2.3 Localization
      • 5.2.4 Formatting floating-point numbers
    • 5.3 Formatting a custom type
      • 5.3.1 Writing a custom formatter
      • 5.3.2 Parsing a custom format specifier
    • 5.4 Referring to a format argument
    • 5.5 Using a custom buffer
      • 5.5.1 Formatting into a dynamically sized buffer
      • 5.5.2 Formatting into a fixed sized buffer
    • 5.6 Writing our own logging function
      • 5.6.1 Prefer make_format_args when forwarding an argument pack
      • 5.6.2 Create the format specifier at compile-time
      • 5.6.3 Formatting the time
  • 6 Three-way comparisons: Simplify your comparisons
    • 6.1 Writing a class with equal comparison
      • 6.1.1 Comparing different types
      • 6.1.2 Less hand-written code with operator reverse, rewrite and =default
    • 6.2 Writing a class with ordering comparison, pre C++20
    • 6.3 Writing a class with ordering comparison in C++20
      • 6.3.1 Member-wise comparison with =default
    • 6.4 The different comparison categories
      • 6.4.1 The comparison categories
      • 6.4.2 The comparison strength: strong or weak
      • 6.4.3 Another comparison strength: partial ordering
      • 6.4.4 Named comparison functions
    • 6.5 Converting between comparison categories
    • 6.6 New operator abilities: reverse and rewrite
    • 6.7 The power of the default spaceship
    • 6.8 Applying a custom sort order
    • 6.9 Spaceship-operation interaction with existing code
  • 7 Lambdas in C++20: New features
    • 7.1 [=, this] as a lambda capture
    • 7.2 Default-constructible lambdas
    • 7.3 Captureless lambdas in unevaluated contexts
    • 7.4 Lambdas in generic code
      • 7.4.1 Lambdas with templated-head
      • 7.4.2 Variadic lambda arguments
      • 7.4.3 Forwarding variadic lambda arguments
    • 7.5 Pack expansions in lambda init-captures
    • 7.6 Restricting lambdas with Concepts
  • 8 Aggregate initialization
    • 8.1 What is an aggregate
    • 8.2 Designated initializers
      • 8.2.1 Designated initializers in C
      • 8.2.2 Designated initializers in C++20
      • 8.2.3 Initializing a subset of an aggregate with designated initializers
      • 8.2.4 Initialize a subset with designated initializers without in-class member initializers
      • 8.2.5 Named arguments in C++: Aggregates with designated initializers
      • 8.2.6 Overload resolution and designated initializers
    • 8.3 Direct-initialization for aggregates
      • 8.3.1 Initialization forms: Braced or parenthesis initialization
      • 8.3.2 Aggregates with user-declared constructors
    • 8.4 Class Template Argument Deduction for aggregates
  • 9 Class-types as non-type template parameters
    • 9.1 What are non-type template parameters again
    • 9.2 The requirements for class types as non-type template parameters
    • 9.3 Class types as non-type template parameters
      • 9.3.1 A first contact with class types as NTTP
      • 9.3.2 What compile-time data do we have
    • 9.4 Building a format function with specifier count check
      • 9.4.1 A first print function
      • 9.4.2 Optimizing the format string creation
      • 9.4.3 Checking the number of specifiers in a format string
      • 9.4.4 Checking if type and specifiers do match
      • 9.4.5 Enable more use-cases and prevent mistakes
  • 10 New STL elements
    • 10.1 bit_cast: Reinterpreting your objects
    • 10.2 endian: Endianess detection at compile time
    • 10.3 to_array
    • 10.4 span: A view of continuous memory
    • 10.5 source_location: The modern way of __FUNCTION__
      • 10.5.1 Writing a custom assert function
      • 10.5.2 Writing a custom assert function with C++20
      • 10.5.3 Writing a custom log function with C++20
    • 10.6 contains for all associative containers
    • 10.7 start_with ends_with for std::string
  • 11 Language Updates
    • 11.1 Range-based for-loops with initializers
      • 11.1.1 Using a counter-variable in a range-based for-loop
      • 11.1.2 A workaround for temporaries
    • 11.2 New Attributes
      • 11.2.1 likely / unlikely
      • 11.2.2 no_unique_address
    • 11.3 using enums
    • 11.4 conditional explicit
      • 11.4.1 Writing a well behaving wrapper
      • 11.4.2 Communicate your intention, explicitly
  • 12 Doing (more) things at compile-time
    • 12.1 The two worlds: compile- vs. run-time
      • 12.1.1 The benefit of compile-time execution
    • 12.2 is_constant_evaluated: Is this a constexpr-context?
      • 12.2.1 Different things at compile- and run-time
      • 12.2.2 is_constant_evaluated is a run-time value
    • 12.3 Less restrictive constexpr-function requirements
      • 12.3.1 new / delete: Dynamic allocations during compile-time
      • 12.3.2 A constexpr std::vector
    • 12.4 Utilizing the new compile-time world: Sketching a car racing game
    • 12.5 consteval: Do things guaranteed at compile-time
      • 12.5.1 as_constant a use-case for consteval
      • 12.5.2 Force compile-time evaluation for compile-time checks
      • 12.5.3 is_constant_evaluated doesn't make it compile-time
    • 12.6 constinit: Initialize a non- const object at compile-time
      • 12.6.1 The static initialization order problem
      • 12.6.2 Ensure compile-time initialization
  • Acronyms
  • Bibliography
  • Index

Feedback

As the book is unfinished yet, some thing are still under construction. However, I appreciate your feedback. In case you like to be a proof reader please contact me, if selected you get a free copy.