81 lines
3.2 KiB
C#
81 lines
3.2 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.Linq;
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using CommunityToolkit.Mvvm.Input;
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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="IRelayCommand"/> properties in generated properties. When this attribute is
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/// used, the generated property setter will also call <see cref="IRelayCommand.NotifyCanExecuteChanged"/> for the properties specified
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/// in the attribute data, causing the validation logic for the command to be executed again. This can be useful to keep the code compact
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/// when there are one or more dependent commands that should also be notified when a property is updated. If this attribute is used in
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/// a field without <see cref="ObservablePropertyAttribute"/>, it is ignored (just like <see cref="NotifyPropertyChangedForAttribute"/>).
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/// <para>
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/// In order to use this attribute, the target property has to implement the <see cref="IRelayCommand"/> interface.
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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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/// [NotifyCanExecuteChangedFor(nameof(GreetUserCommand))]
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/// private string name;
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///
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/// public IRelayCommand GreetUserCommand { get; }
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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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/// GreetUserCommand.NotifyCanExecuteChanged();
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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 NotifyCanExecuteChangedForAttribute : Attribute
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{
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/// <summary>
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/// Initializes a new instance of the <see cref="NotifyCanExecuteChangedForAttribute"/> class.
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/// </summary>
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/// <param name="commandName">The name of the command to also notify when the annotated property changes.</param>
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public NotifyCanExecuteChangedForAttribute(string commandName)
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{
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CommandNames = new[] { commandName };
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}
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/// <summary>
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/// Initializes a new instance of the <see cref="NotifyCanExecuteChangedForAttribute"/> class.
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/// </summary>
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/// <param name="commandName">The name of the property to also notify when the annotated property changes.</param>
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/// <param name="otherCommandNames">
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/// The other command 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 commands from the same attribute, to keep the code more compact.
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/// </param>
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public NotifyCanExecuteChangedForAttribute(string commandName, params string[] otherCommandNames)
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{
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CommandNames = new[] { commandName }.Concat(otherCommandNames).ToArray();
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}
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/// <summary>
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/// Gets the command names to also notify when the annotated property changes.
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/// </summary>
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public string[] CommandNames { get; }
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}
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