C# 9 and 10 - What's cool?
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Showing the best features of C# 9 and 10, including the changes for nullable reference types since C# 8, records with classes and structs, top level statements with the enhancements for file-scoped namespaces, global using directives, and implicit usings, as well as source code generators including the JSON serializer source generator that comes with .NET 6
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C# 9 and 10 - What's cool?
- 1. C# 9 und 10 – What’s cool? Christian Nagel https://csharp.christiannagel.com
- 2. Christian Nagel • Training • Coaching • Consulting • Development • Microsoft MVP • www.cninnovation.com • csharp.christiannagel.com • @christiannagel
- 3. Topics • Nullable Reference Types • Top level statements • Records • Source Generators
- 5. Phases • C# 8: Nullable Adoption Phase • Use nullable with libraries • C# 9: Enhancements • Attributes, Generics • C# 10 / .NET 6 • Defaults with Templates
- 6. Nullable Reference Types • New since C# 8: null state analysis • Enhancements with C# 9 • Explicitly enable nullable (nullable contexts) • Nullable oblivious (C# 7.3 or earlier) • #nullable (source code) • <nullable> (project setting)
- 7. No fixes with… • Nullability doesn’t fix all issues! • Arrays • Structs…
- 8. Enhancements • Attributes • AllowNull, DisallowNull (Precondition) • MaybeNull, NotNull (Postcondition) • NotNullWhen, NotNullIfNotNull, MaybeNullWhen (Conditional post-condition) • MemberNotNull, MemberNotNullWhen (Helper methods) • Generics • T? doesn’t require class or struct (C# 9) • notnull, class?, default constraints
- 10. New Hello World • C# 6 • using static • C# 9 • Top-Level Statements • C# 10 • global using directives • file scoped namespaces • Implicit usings
- 11. Samples • Hello, World! • Empty Web • Minimal API
- 12. Records
- 13. C# 9 - Class Records • Nominal or Positional • Equality Implementation • init-only setters • with expressions • Deconstruction
- 14. C# 10 - Struct Records • Nominal or Positional • Equality Implementation • init-only setters • with expressions (all structs) • Deconstruction
- 15. Samples • Records with classes and structs • Inheritance • Records with EF Core
- 17. What are Source Generators? • Invoked by the C# Compiler • Generated code can be used by the application • Enhanced partial keyword
- 18. Samples • Simple Source Generator • .NET 6 JSON Serializer
- 19. There’s more…
- 20. C# 9 • Records • Init-only setters • Top-level statements • Covariant return types • Target-typed new expressions • Pattern matching enhancements • Static anonymous functions • Attributes on local functions • Extension GetEnumerator • Lambda discard parameters • Native sized integers • Function pointers • Module initializers • Extensions for partial methods • Source code generators • Generic constraint changes for nullability
- 21. C# 10 • global using directives • file-scoped namespaces • Custom parameterless constructors with structs • Field and property initializers with structs • with expression with structs • record struct • Lambda improvements (attributes, natural delegate type) • Extended property patterns • Const interpolated strings • Record types can seal ToString • Assignment and declaration in the same deconstruction • Generic Attributes • Templates change with new language features and nullability • Implicit Usings • Static abstract members in interfaces (preview)
- 22. Summary • Nullable Reference Types • Top-level statements • Records • Source Generators
- 23. Thank you! • Source code: https://github.com/christiannagel • More information: https://csharp.christiannagel.com