feature: Add record base C# 9

.editorconfig

@@ -10,12 +10,11 @@ root = true
 insert_final_newline = true
 indent_style = space
 indent_size = 4
-
-[project.json]
-indent_size = 2
+trim_trailing_whitespace = true
 
 # C# files
 [*.cs]
+
 # New line preferences
 csharp_new_line_before_open_brace = all
 csharp_new_line_before_else = true
@@ -42,11 +41,6 @@ dotnet_style_qualification_for_property = false:suggestion
 dotnet_style_qualification_for_method = false:suggestion
 dotnet_style_qualification_for_event = false:suggestion
 
-# only use var when it's obvious what the variable type is
-csharp_style_var_for_built_in_types = false:none
-csharp_style_var_when_type_is_apparent = true:suggestion
-csharp_style_var_elsewhere = true:suggestion
-
 # Types: use keywords instead of BCL types, and permit var only when the type is clear
 csharp_style_var_for_built_in_types = false:suggestion
 csharp_style_var_when_type_is_apparent = false:none
@@ -62,14 +56,14 @@ dotnet_naming_symbols.constant_fields.applicable_kinds   = field
 dotnet_naming_symbols.constant_fields.required_modifiers = const
 dotnet_naming_style.pascal_case_style.capitalization = pascal_case
 
-# static fields should have s_ prefix
+# static fields should have _ prefix
 dotnet_naming_rule.static_fields_should_have_prefix.severity = suggestion
 dotnet_naming_rule.static_fields_should_have_prefix.symbols  = static_fields
 dotnet_naming_rule.static_fields_should_have_prefix.style    = static_prefix_style
 dotnet_naming_symbols.static_fields.applicable_kinds   = field
 dotnet_naming_symbols.static_fields.required_modifiers = static
 dotnet_naming_symbols.static_fields.applicable_accessibilities = private, internal, private_protected
-dotnet_naming_style.static_prefix_style.required_prefix = s_
+dotnet_naming_style.static_prefix_style.required_prefix = _
 dotnet_naming_style.static_prefix_style.capitalization = camel_case
 
 # internal and private fields should be _camelCase
@@ -84,7 +78,7 @@ dotnet_naming_style.camel_case_underscore_style.capitalization = camel_case
 # Code style defaults
 csharp_using_directive_placement = outside_namespace:suggestion
 dotnet_sort_system_directives_first = true
-csharp_prefer_braces = true:silent
+csharp_prefer_braces = true:suggestion
 csharp_preserve_single_line_blocks = true:none
 csharp_preserve_single_line_statements = false:none
 csharp_prefer_static_local_function = true:suggestion
@@ -105,8 +99,8 @@ dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggesti
 dotnet_style_prefer_inferred_tuple_names = true:suggestion
 dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
 dotnet_style_prefer_auto_properties = true:suggestion
-dotnet_style_prefer_conditional_expression_over_assignment = true:silent
-dotnet_style_prefer_conditional_expression_over_return = true:silent
+dotnet_style_prefer_conditional_expression_over_assignment = true:suggestion
+dotnet_style_prefer_conditional_expression_over_return = true:suggestion
 csharp_prefer_simple_default_expression = true:suggestion
 
 # Expression-bodied members
@@ -436,9 +430,12 @@ curly_bracket_next_line = true
 indent_brace_style = Allman
 
 # Xml project files
-[*.{csproj,vcxproj,vcxproj.filters,proj,nativeproj,locproj}]
+[*.{csproj,vbproj,vcxproj,vcxproj.filters,proj,nativeproj,locproj}]
 indent_size = 2
 
+[*.{csproj,vbproj,proj,nativeproj,locproj}]
+charset = utf-8
+
 # Xml build files
 [*.builds]
 indent_size = 2
@@ -451,8 +448,13 @@ indent_size = 2
 [*.{props,targets,config,nuspec}]
 indent_size = 2
 
+# YAML config files
+[*.{yml,yaml}]
+indent_size = 2
+
 # Shell scripts
 [*.sh]
 end_of_line = lf
-[*.{cmd, bat}]
+
+[*.{cmd,bat}]
 end_of_line = crlf

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net472.approved.txt

@@ -631,6 +631,32 @@ namespace ReactiveUI
         public ReactivePropertyChangingEventArgs(TSender sender, string? propertyName) { }
         public TSender Sender { get; }
     }
+    [System.Runtime.Serialization.DataContract]
+    public class ReactiveRecord : ReactiveUI.IHandleObservableErrors, ReactiveUI.IReactiveNotifyPropertyChanged<ReactiveUI.IReactiveObject>, ReactiveUI.IReactiveObject, Splat.IEnableLogger, System.ComponentModel.INotifyPropertyChanged, System.ComponentModel.INotifyPropertyChanging, System.IEquatable<ReactiveUI.ReactiveRecord>
+    {
+        public ReactiveRecord() { }
+        protected ReactiveRecord(ReactiveUI.ReactiveRecord original) { }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changed { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changing { get; }
+        protected virtual System.Type EqualityContract { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<System.Exception> ThrownExceptions { get; }
+        public event System.ComponentModel.PropertyChangedEventHandler? PropertyChanged;
+        public event System.ComponentModel.PropertyChangingEventHandler? PropertyChanging;
+        public virtual ReactiveUI.ReactiveRecord <Clone>$() { }
+        public bool AreChangeNotificationsEnabled() { }
+        public System.IDisposable DelayChangeNotifications() { }
+        public virtual bool Equals(ReactiveUI.ReactiveRecord? other) { }
+        public override bool Equals(object? obj) { }
+        public override int GetHashCode() { }
+        protected virtual bool PrintMembers(System.Text.StringBuilder builder) { }
+        public System.IDisposable SuppressChangeNotifications() { }
+        public override string ToString() { }
+        public static bool operator !=(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+        public static bool operator ==(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+    }
     public static class Reflection
     {
         public static string ExpressionToPropertyNames(System.Linq.Expressions.Expression expression) { }

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.net5.0.approved.txt

@@ -626,6 +626,32 @@ namespace ReactiveUI
         public ReactivePropertyChangingEventArgs(TSender sender, string? propertyName) { }
         public TSender Sender { get; }
     }
+    [System.Runtime.Serialization.DataContract]
+    public class ReactiveRecord : ReactiveUI.IHandleObservableErrors, ReactiveUI.IReactiveNotifyPropertyChanged<ReactiveUI.IReactiveObject>, ReactiveUI.IReactiveObject, Splat.IEnableLogger, System.ComponentModel.INotifyPropertyChanged, System.ComponentModel.INotifyPropertyChanging, System.IEquatable<ReactiveUI.ReactiveRecord>
+    {
+        public ReactiveRecord() { }
+        protected ReactiveRecord(ReactiveUI.ReactiveRecord original) { }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changed { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changing { get; }
+        protected virtual System.Type EqualityContract { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<System.Exception> ThrownExceptions { get; }
+        public event System.ComponentModel.PropertyChangedEventHandler? PropertyChanged;
+        public event System.ComponentModel.PropertyChangingEventHandler? PropertyChanging;
+        public virtual ReactiveUI.ReactiveRecord <Clone>$() { }
+        public bool AreChangeNotificationsEnabled() { }
+        public System.IDisposable DelayChangeNotifications() { }
+        public virtual bool Equals(ReactiveUI.ReactiveRecord? other) { }
+        public override bool Equals(object? obj) { }
+        public override int GetHashCode() { }
+        protected virtual bool PrintMembers(System.Text.StringBuilder builder) { }
+        public System.IDisposable SuppressChangeNotifications() { }
+        public override string ToString() { }
+        public static bool operator !=(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+        public static bool operator ==(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+    }
     public static class Reflection
     {
         public static string ExpressionToPropertyNames(System.Linq.Expressions.Expression expression) { }

src/ReactiveUI.Tests/API/ApiApprovalTests.ReactiveUI.netcoreapp3.1.approved.txt

@@ -624,6 +624,32 @@ namespace ReactiveUI
         public ReactivePropertyChangingEventArgs(TSender sender, string? propertyName) { }
         public TSender Sender { get; }
     }
+    [System.Runtime.Serialization.DataContract]
+    public class ReactiveRecord : ReactiveUI.IHandleObservableErrors, ReactiveUI.IReactiveNotifyPropertyChanged<ReactiveUI.IReactiveObject>, ReactiveUI.IReactiveObject, Splat.IEnableLogger, System.ComponentModel.INotifyPropertyChanged, System.ComponentModel.INotifyPropertyChanging, System.IEquatable<ReactiveUI.ReactiveRecord>
+    {
+        public ReactiveRecord() { }
+        protected ReactiveRecord(ReactiveUI.ReactiveRecord original) { }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changed { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<ReactiveUI.IReactivePropertyChangedEventArgs<ReactiveUI.IReactiveObject>> Changing { get; }
+        protected virtual System.Type EqualityContract { get; }
+        [System.Runtime.Serialization.IgnoreDataMember]
+        public System.IObservable<System.Exception> ThrownExceptions { get; }
+        public event System.ComponentModel.PropertyChangedEventHandler? PropertyChanged;
+        public event System.ComponentModel.PropertyChangingEventHandler? PropertyChanging;
+        public virtual ReactiveUI.ReactiveRecord <Clone>$() { }
+        public bool AreChangeNotificationsEnabled() { }
+        public System.IDisposable DelayChangeNotifications() { }
+        public virtual bool Equals(ReactiveUI.ReactiveRecord? other) { }
+        public override bool Equals(object? obj) { }
+        public override int GetHashCode() { }
+        protected virtual bool PrintMembers(System.Text.StringBuilder builder) { }
+        public System.IDisposable SuppressChangeNotifications() { }
+        public override string ToString() { }
+        public static bool operator !=(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+        public static bool operator ==(ReactiveUI.ReactiveRecord? r1, ReactiveUI.ReactiveRecord? r2) { }
+    }
     public static class Reflection
     {
         public static string ExpressionToPropertyNames(System.Linq.Expressions.Expression expression) { }

src/ReactiveUI/IsExternalInit.cs

@@ -0,0 +1,18 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using System.ComponentModel;
+
+namespace System.Runtime.CompilerServices
+{
+    /// <summary>
+    /// Reserved to be used by the compiler for tracking metadata.
+    /// This class should not be used by developers in source code.
+    /// </summary>
+    [EditorBrowsable(EditorBrowsableState.Never)]
+    internal static class IsExternalInit
+    {
+    }
+}

src/ReactiveUI/ReactiveObject/ReactiveRecord.cs

@@ -0,0 +1,111 @@
+// Copyright (c) 2021 .NET Foundation and Contributors. All rights reserved.
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+using System;
+using System.ComponentModel;
+using System.Reactive;
+using System.Runtime.Serialization;
+using System.Threading;
+
+namespace ReactiveUI
+{
+    /// <summary>
+    /// ReactiveObject is the base object for ViewModel classes, and it
+    /// implements INotifyPropertyChanged. In addition, ReactiveObject provides
+    /// Changing and Changed Observables to monitor object changes.
+    /// </summary>
+    [DataContract]
+    public record ReactiveRecord : IReactiveNotifyPropertyChanged<IReactiveObject>, IHandleObservableErrors, IReactiveObject
+    {
+        private readonly Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>> _changing;
+        private readonly Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>> _changed;
+        private readonly Lazy<Unit> _propertyChangingEventsSubscribed;
+        private readonly Lazy<Unit> _propertyChangedEventsSubscribed;
+        private readonly Lazy<IObservable<Exception>> _thrownExceptions;
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ReactiveRecord"/> class.
+        /// </summary>
+        public ReactiveRecord()
+        {
+            _changing = new Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>>(() => ((IReactiveObject)this).GetChangingObservable(), LazyThreadSafetyMode.PublicationOnly);
+            _changed = new Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>>(() => ((IReactiveObject)this).GetChangedObservable(), LazyThreadSafetyMode.PublicationOnly);
+            _propertyChangingEventsSubscribed = new Lazy<Unit>(
+                                                        () =>
+                                                        {
+                                                            this.SubscribePropertyChangingEvents();
+                                                            return Unit.Default;
+                                                        },
+                                                        LazyThreadSafetyMode.PublicationOnly);
+            _propertyChangedEventsSubscribed = new Lazy<Unit>(
+                                                        () =>
+                                                        {
+                                                            this.SubscribePropertyChangedEvents();
+                                                            return Unit.Default;
+                                                        },
+                                                        LazyThreadSafetyMode.PublicationOnly);
+            _thrownExceptions = new Lazy<IObservable<Exception>>(this.GetThrownExceptionsObservable, LazyThreadSafetyMode.PublicationOnly);
+        }
+
+        /// <inheritdoc/>
+        public event PropertyChangingEventHandler? PropertyChanging
+        {
+            add
+            {
+                _ = _propertyChangingEventsSubscribed.Value;
+                PropertyChangingHandler += value;
+            }
+            remove => PropertyChangingHandler -= value;
+        }
+
+        /// <inheritdoc/>
+        public event PropertyChangedEventHandler? PropertyChanged
+        {
+            add
+            {
+                _ = _propertyChangedEventsSubscribed.Value;
+                PropertyChangedHandler += value;
+            }
+            remove => PropertyChangedHandler -= value;
+        }
+
+        private event PropertyChangingEventHandler? PropertyChangingHandler;
+
+        private event PropertyChangedEventHandler? PropertyChangedHandler;
+
+        /// <inheritdoc />
+        [IgnoreDataMember]
+        public IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>> Changing => _changing.Value;
+
+        /// <inheritdoc />
+        [IgnoreDataMember]
+        public IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>> Changed => _changed.Value;
+
+        /// <inheritdoc/>
+        [IgnoreDataMember]
+        public IObservable<Exception> ThrownExceptions => _thrownExceptions.Value;
+
+        /// <inheritdoc/>
+        void IReactiveObject.RaisePropertyChanging(PropertyChangingEventArgs args) => PropertyChangingHandler?.Invoke(this, args);
+
+        /// <inheritdoc/>
+        void IReactiveObject.RaisePropertyChanged(PropertyChangedEventArgs args) => PropertyChangedHandler?.Invoke(this, args);
+
+        /// <inheritdoc/>
+        public IDisposable SuppressChangeNotifications() => IReactiveObjectExtensions.SuppressChangeNotifications(this);
+
+        /// <summary>
+        /// Determines if change notifications are enabled or not.
+        /// </summary>
+        /// <returns>A value indicating whether change notifications are enabled.</returns>
+        public bool AreChangeNotificationsEnabled() => IReactiveObjectExtensions.AreChangeNotificationsEnabled(this);
+
+        /// <summary>
+        /// Delays notifications until the return IDisposable is disposed.
+        /// </summary>
+        /// <returns>A disposable which when disposed will send delayed notifications.</returns>
+        public IDisposable DelayChangeNotifications() => IReactiveObjectExtensions.DelayChangeNotifications(this);
+    }
+}

version.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://raw.githubusercontent.com/dotnet/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
-  "version": "13.2",
+  "version": "13.3",
   "publicReleaseRefSpec": [
     "^refs/heads/master$", // we release out of master
     "^refs/heads/main$",