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![ref return / ref local
• Eine Referenz auf einen Value Type zurück liefern
• ref local
public class Container
{
public Container(int[] data) => _data = data;
private int[] _data;
public ref int GetItem(int index) => ref _data[index];
}
ref int item = ref c.GetItem(3);](https://image.slidesharecdn.com/referencesemantics-190228065436/75/Reference-Semantik-mit-C-und-NET-Core-BASTA-2019-12-2048.jpg)
![ref readonly
• Eine Referenz, aber nicht änderbar
public ref readonly int GetItem(int index) => ref _data[index];
ref readonly int item = ref c.GetItem(3);
// item = 4; // error – cannot be changed!](https://image.slidesharecdn.com/referencesemantics-190228065436/75/Reference-Semantik-mit-C-und-NET-Core-BASTA-2019-13-2048.jpg)
Uploaded byChristian Nagel
Reference Semantik mit C# und .NET Core - BASTA 2019
The document discusses reference semantics in C# and .NET Core, covering concepts such as pass by reference versus pass by value, the use of reference types and value types, and the implementation of struct guidelines. It highlights advancements like readonly structs and new memory management features which improve performance while reducing memory allocations. Additionally, it provides resources for further information and training on C# and related technologies.
Reference Semantik mit C# und .NET Core - BASTA 2019
- 1. Referenz Semantik mit C#und .NET Core @christiannagel
- 2. Referenz Semantik mitC# Demo
- 3. Ref / Value •class • Pass by reference • Stored on the heap Reference Types • struct • Pass by value • Stored on the stack – or the heap • Boxing! Value Types
- 4.
- 5. Christian Nagel • Training •Coaching • Consulting • Development • Microsoft MVP • www.cninnovation.com • csharp.christiannagel.com
- 6. Struct .NET Design Guidelines • Donot provide a default constructor • Not allowed by C# • Do not define mutable value types • Developers might not be aware to mutate a copy • Do ensure that zero/false/null state is valid • Prevents accidential creation of invalid instances • Do implement IEquatable<T> • Object.Equals causes boxing • Do not explicitly extend value types • Not allowed by C#
- 7. Rule: "Do notdefine mutable value types"! Ausnahmen! short/int/long/ float/double Tuples
- 10. readonly struct • C#7.2 readonly struct MyStruct { public MyStruct(int myProperty) => MyProperty = myProperty; public int MyProperty { get; } }
- 11. Demo • ref local •ref return • readonly ref • in
- 12. ref return /ref local • Eine Referenz auf einen Value Type zurück liefern • ref local public class Container { public Container(int[] data) => _data = data; private int[] _data; public ref int GetItem(int index) => ref _data[index]; } ref int item = ref c.GetItem(3);
- 13. ref readonly • EineReferenz, aber nicht änderbar public ref readonly int GetItem(int index) => ref _data[index]; ref readonly int item = ref c.GetItem(3); // item = 4; // error – cannot be changed!
- 14. in Parameter Modifier •Pass by ref – aber nicht änderbar void PassByReference(in int x) { // cannot change x }
- 15. Demo • ref struct •Span<T> • Slices • Span using arrays and strings
- 16. The Span<T> Type stack only Verwendetref return Zugriff auf kontinuierliches Memory Stack, Managed Heap, Native Heap
- 17.
- 18. String Performance (.NETCore 2.1) • String.Equal • String.IndexOf, String.LastIndexOf • String.ToLower • String.Split • String.Format • StringBuilder.Append • int.Parse • Algorithms from vectorized computing (like used with Span<T>) • Using Span<T> internally • Reducing allocations • Fast paths for common scenarios
- 19. ArrayPool Werden viele Arraysdynamisch erzeugt? ArrayPool verwaltet Arrays Rent Arrays vom Pool Return Arrays zum Pool Thread safe! .NET Core 2.1 MemoryPool für Buffer
- 20. Span<T> Overloads Neue Overloads für StreamOperations Vereinfacht Code – Größenangaben entfallen Performanceverbesserung
- 21. Pipelines • Management vonBuffers • Wird von Kestrel und SignalR verwendet • System.IO.Pipelines • Pipe • allocates and manages memory • PipeReader / PipeWriter • read and write side of the pipe • ReadOnlySequence • linked list of buffers
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- 24. More Information • https://github.com/ProfessionalCSharp •https://csharp.christiannagel.com • https://www.cninnovation.com • Training & Coaching