134 lines
4.5 KiB
C#
134 lines
4.5 KiB
C#
#region Apache License 2.0
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/*
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Nuclex .NET Framework
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Copyright (C) 2002-2024 Markus Ewald / Nuclex Development Labs
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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#endregion // Apache License 2.0
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using System;
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using System.ComponentModel;
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using System.Diagnostics;
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#if !NO_LINQ_EXPRESSIONS
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using System.Linq.Expressions;
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#endif
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using System.Reflection;
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namespace Nuclex.Support {
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/// <summary>Base class for objects that support property change notifications</summary>
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#if !NO_SERIALIZATION
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[Serializable]
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#endif
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public abstract class Observable : INotifyPropertyChanged {
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/// <summary>Raised when a property of the instance has changed its value</summary>
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#if !NO_SERIALIZATION
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[field: NonSerialized]
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#endif
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public event PropertyChangedEventHandler PropertyChanged;
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#if !NO_LINQ_EXPRESSIONS
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/// <summary>Triggers the PropertyChanged event for the specified property</summary>
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/// <param name="property">
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/// Lambda expression for the property that will be reported to have changed
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/// </param>
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/// <remarks>
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/// <para>
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/// This notification should be fired post-change, i.e. when the property has
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/// already changed its value.
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/// </para>
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/// <example>
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/// <code>
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/// public int Limit {
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/// get { return this.limit; }
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/// set {
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/// if(value != this.limit) {
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/// this.limit = value;
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/// OnPropertyChanged(() => Limit);
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/// }
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/// }
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/// }
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/// </code>
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/// </example>
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/// </remarks>
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[Obsolete("Prefer the C# 'nameof()' operator to using a Linq expression")]
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protected void OnPropertyChanged<TProperty>(Expression<Func<TProperty>> property) {
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PropertyChangedEventHandler copy = PropertyChanged;
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if(copy != null) {
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copy(this, PropertyChangedEventArgsHelper.GetArgumentsFor(property));
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}
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}
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#endif // !NO_LINQ_EXPRESSIONS
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/// <summary>Triggers the PropertyChanged event for the specified property</summary>
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/// <param name="propertyName">Name of the property that has changed its value</param>
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/// <remarks>
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/// <para>
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/// This notification should be fired post-change, i.e. when the property has
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/// already changed its value. If possible, use the other overload of this
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/// method to ensure the property name will be updated during F2 refactoring.
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/// </para>
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/// <example>
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/// <code>
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/// public int Limit {
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/// get { return this.limit; }
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/// set {
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/// if(value != this.limit) {
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/// this.limit = value;
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/// OnPropertyChanged("Limit"); // Note: prefer lambda exp whenever possible
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/// }
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/// }
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/// }
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/// </code>
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/// </example>
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/// </remarks>
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protected virtual void OnPropertyChanged(string propertyName) {
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enforceChangedPropertyExists(propertyName);
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PropertyChangedEventHandler copy = PropertyChanged;
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if(copy != null) {
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copy(this, PropertyChangedEventArgsHelper.GetArgumentsFor(propertyName));
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}
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}
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/// <summary>Ensures that a property with the specified name exists in the type</summary>
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/// <param name="propertyName">Property name that will be checked</param>
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[Conditional("DEBUG")]
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private void enforceChangedPropertyExists(string propertyName) {
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// An empty string or null indicates that all properties have changed
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if(string.IsNullOrEmpty(propertyName)) {
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return;
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}
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// Any other string needs to match a property name
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PropertyInfo property = GetType().GetProperty(propertyName);
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if(property == null) {
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throw new ArgumentException(
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string.Format(
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"Type '{0}' tried to raise a change notification for property '{1}', " +
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"but no such property exists!",
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GetType().Name, propertyName
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),
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"propertyName"
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);
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}
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}
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}
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} // namespace Nuclex.Support
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