ObservablePropertyAttribute.cs

// 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 more information.

using System;
using System.ComponentModel;

namespace CommunityToolkit.Mvvm.ComponentModel;

/// <summary>
/// An attribute that indicates that a given field should be wrapped by a generated observable property.
/// In order to use this attribute, the containing type has to inherit from <see cref="ObservableObject"/>, or it
/// must be using <see cref="ObservableObjectAttribute"/> or <see cref="INotifyPropertyChangedAttribute"/>.
/// If the containing type also implements the <see cref="INotifyPropertyChanging"/> (that is, if it either inherits from
/// <see cref="ObservableObject"/> or is using <see cref="ObservableObjectAttribute"/>), then the generated code will
/// also invoke <see cref="ObservableObject.OnPropertyChanging(PropertyChangingEventArgs)"/> to signal that event.
/// <para>
/// This attribute can be used as follows:
/// <code>
/// partial class MyViewModel : ObservableObject
/// {
///     [ObservableProperty]
///     private string name;
///
///     [ObservableProperty]
///     private bool isEnabled;
/// }
/// </code>
/// </para>
/// And with this, code analogous to this will be generated:
/// <code>
/// partial class MyViewModel
/// {
///     public string Name
///     {
///         get => name;
///         set => SetProperty(ref name, value);
///     }
///
///     public bool IsEnabled
///     {
///         get => isEnabled;
///         set => SetProperty(ref isEnabled, value);
///     }
/// }
/// </code>
/// </summary>
/// <remarks>
/// The generated properties will automatically use the <c>UpperCamelCase</c> format for their names,
/// which will be derived from the field names. The generator can also recognize fields using either
/// the <c>_lowerCamel</c> or <c>m_lowerCamel</c> naming scheme. Otherwise, the first character in the
/// source field name will be converted to uppercase (eg. <c>isEnabled</c> to <c>IsEnabled</c>).
/// </remarks>
[AttributeUsage(AttributeTargets.Field, AllowMultiple = false, Inherited = false)]
public sealed class ObservablePropertyAttribute : Attribute
{
    /// <summary>
    /// Initializes a new instance of the <see cref="ObservablePropertyAttribute"/> class. 
    /// </summary>
    /// <param name="hidesInheritedProperty">
    /// Specifies if the generated property will hide an inherited property declaration.
    /// </param>
    public ObservablePropertyAttribute(bool hidesInheritedProperty = false)
    {
        Hidesinheritedproperty = hidesInheritedProperty;
    }

    /// <summary>
    /// Specifies if the generated property will hide an inherited property declaration.
    /// </summary>
    public bool Hidesinheritedproperty { get; }
}