100 lines
4.0 KiB
C#
100 lines
4.0 KiB
C#
// Licensed to the .NET Foundation under one or more agreements.
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// The .NET Foundation licenses this file to you under the MIT license.
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// See the LICENSE file in the project root for more information.
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using System;
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using System.ComponentModel;
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using System.Linq;
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namespace CommunityToolkit.Mvvm.ComponentModel;
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/// <summary>
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/// An attribute that can be used to support <see cref="ObservablePropertyAttribute"/> in generated properties. When this attribute is
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/// used, the generated property setter will also call <see cref="ObservableObject.OnPropertyChanged(string?)"/> (or the equivalent
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/// method in the target class) for the properties specified in the attribute data. This can be useful to keep the code compact when
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/// there are one or more dependent properties that should also be reported as updated when the value of the annotated observable
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/// property is changed. If this attribute is used in a field without <see cref="ObservablePropertyAttribute"/>, it is ignored.
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/// <para>
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/// In order to use this attribute, the containing type has to implement the <see cref="INotifyPropertyChanged"/> interface
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/// and expose a method with the same signature as <see cref="ObservableObject.OnPropertyChanged(string?)"/>. If the containing
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/// type also implements the <see cref="INotifyPropertyChanging"/> interface and exposes a method with the same signature as
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/// <see cref="ObservableObject.OnPropertyChanging(string?)"/>, then this method will be invoked as well by the property setter.
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/// </para>
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/// <para>
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/// This attribute can be used as follows:
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/// <code>
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/// partial class MyViewModel : ObservableObject
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/// {
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/// [ObservableProperty]
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/// [NotifyPropertyChangedFor(nameof(FullName))]
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/// private string name;
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///
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/// [ObservableProperty]
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/// [NotifyPropertyChangedFor(nameof(FullName))]
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/// private string surname;
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///
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/// public string FullName => $"{Name} {Surname}";
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/// }
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/// </code>
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/// </para>
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/// And with this, code analogous to this will be generated:
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/// <code>
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/// partial class MyViewModel
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/// {
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/// public string Name
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/// {
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/// get => name;
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/// set
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/// {
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/// if (SetProperty(ref name, value))
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/// {
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/// OnPropertyChanged(nameof(FullName));
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/// }
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/// }
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/// }
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///
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/// public string Surname
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/// {
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/// get => surname;
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/// set
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/// {
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/// if (SetProperty(ref surname, value))
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/// {
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/// OnPropertyChanged(nameof(FullName));
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/// }
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/// }
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/// }
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/// }
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/// </code>
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/// </summary>
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[AttributeUsage(AttributeTargets.Field, AllowMultiple = true, Inherited = false)]
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public sealed class NotifyPropertyChangedForAttribute : Attribute
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{
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/// <summary>
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/// Initializes a new instance of the <see cref="NotifyPropertyChangedForAttribute"/> class.
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/// </summary>
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/// <param name="propertyName">The name of the property to also notify when the annotated property changes.</param>
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public NotifyPropertyChangedForAttribute(string propertyName)
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{
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PropertyNames = new[] { propertyName };
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="NotifyPropertyChangedForAttribute"/> class.
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/// </summary>
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/// <param name="propertyName">The name of the property to also notify when the annotated property changes.</param>
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/// <param name="otherPropertyNames">
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/// The other property names to also notify when the annotated property changes. This parameter can optionally
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/// be used to indicate a series of dependent properties from the same attribute, to keep the code more compact.
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/// </param>
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public NotifyPropertyChangedForAttribute(string propertyName, params string[] otherPropertyNames)
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{
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PropertyNames = new[] { propertyName }.Concat(otherPropertyNames).ToArray();
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}
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/// <summary>
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/// Gets the property names to also notify when the annotated property changes.
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/// </summary>
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public string[] PropertyNames { get; }
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}
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