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Fix record class & record struct notes

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Marcello 2021-12-30 21:17:29 +01:00
parent 8d80356d2b
commit 20d9d6deb9
1 changed files with 19 additions and 12 deletions
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31
DotNet/C#/C#.md
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@ -320,22 +320,29 @@ Since the names of the attributes of a tuple do not matter (a tuple is an instan
## Records (C# 9)
```cs
// mutable record
public record RecordName
public record Record
{
public Type Property1 { get; init; }
public Type Property2 { get; init; }
// Equals(), Equality Operators, GetHashCode(), ToString() generated by .NET
// Constructor, Deconstructor, Equals(), Equality Operators, GetHashCode(), ToString() generated
}
// same as
public record Record(Type Property1, Type Property2, ...);
public record struct RecordStruct(Type Property1, Type Property2, ...);
// immutable record
public record RecordName ( Type Property1, Type Property2, ...);
// Constructor, Deconstructor, Equals(), Equality Operators, GetHashCode(), ToString() generated by .NET
RecordName record = new RecordName(value1, ...); // instantiation
Record recObj = new Record(value1, ...); // instantiation
//or
RecordName record = new RecordName { Property1 = value1, ...}; // instantiation
Record record = new Record { Property1 = value1, ...}; // instantiation
```
### Custom Behaviour
```cs
public record Record(Type Property1, Type Property2, ...)
{
// provide custom implementation for default maethod
}
```
### `with`-expressions
@ -352,7 +359,7 @@ A record implicitly defines a protected "copy constructor", a constructor that t
The `with` expression causes the copy constructor to get called, and then applies the object initializer on top to change the properties accordingly.
```cs
protected RecordName(RecordName original) { /* copy all the fields */ } // generated
protected Record(Record original) { /* copy all the fields */ } // generated
```
**NOTE**: it's possible to define a custom copy constructor tha will be picked up by the `with` expression.
@ -373,8 +380,8 @@ A with-expression simply calls the hidden "clone" method and applies the object
public record Base{ Type Prop1, Type Prop2 };
public record Derived : Base { Type Prop3 };
Base _base = new Derived { Prop1 = value1, Prop2 = value2, Prop3 = value3 };
newBase = _base with { Prop2 = value }; // new Derived record even if type of _base is Base since _base contains a Derived record
Base @base = new Derived { Prop1 = value1, Prop2 = value2, Prop3 = value3 };
var newBase = @base with { Prop2 = value }; // new Derived record even if type of _base is Base since _base contains a Derived record
```
### Value-based Equality & Inheritance