// Copyright (c) 2019 .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.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 class ReactiveObject : IReactiveNotifyPropertyChanged<IReactiveObject>, IHandleObservableErrors, IReactiveObject

{

private readonly Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>> _changing;

private readonly Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>> _changed;

private readonly Lazy<IObservable<Exception>> _thrownExceptions;

/// <summary>

/// Initializes a new instance of the <see cref="ReactiveObject"/> class.

/// </summary>

public ReactiveObject()

{

_changing = new Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>>(() => ((IReactiveObject)this).GetChangingObservable(), LazyThreadSafetyMode.PublicationOnly);

_changed = new Lazy<IObservable<IReactivePropertyChangedEventArgs<IReactiveObject>>>(() => ((IReactiveObject)this).GetChangedObservable(), LazyThreadSafetyMode.PublicationOnly);

_thrownExceptions = new Lazy<IObservable<Exception>>(this.GetThrownExceptionsObservable, LazyThreadSafetyMode.PublicationOnly);

}

/// <inheritdoc/>

public event PropertyChangingEventHandler PropertyChanging;

/// <inheritdoc/>

public event PropertyChangedEventHandler PropertyChanged;

/// <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) => PropertyChanging?.Invoke(this, args);

/// <inheritdoc/>

void IReactiveObject.RaisePropertyChanged(PropertyChangedEventArgs args) => PropertyChanged?.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);

}

}

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