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    <p>Don't forget one thing : <code>PropertyChanged</code> event is mainly consumed by components that will <strong>use reflection</strong> to get the value of the named property.</p> <p>The most obvious example is databinding.</p> <p>When you fire <code>PropertyChanged</code> event, passing the name of the property as a parameter, you should know that <em>the subscriber of this event is likely to use reflection</em> by calling, for instance, <code>GetProperty</code> (at least the first time if it uses a cache of <code>PropertyInfo</code>), then <code>GetValue</code>. This last call is a dynamic invocation (MethodInfo.Invoke) of the property getter method, which costs more than the <code>GetProperty</code> which only queries meta data. (Note that data binding relies on the whole <a href="http://msdn.microsoft.com/en-us/library/ms171819.aspx" rel="noreferrer">TypeDescriptor</a> thing -- but the default implementation uses reflection.)</p> <p>So, of course using hard code property names when firing PropertyChanged is more efficient than using reflection for dynamically getting the name of the property, but IMHO, it is important to balance your thoughts. In some cases, the performance overhead is not that critical, and you could benefit from some kind on strongly typed event firing mechanism.</p> <p>Here is what I use sometimes in C# 3.0, when performances would not be a concern :</p> <pre><code>public class Person : INotifyPropertyChanged { private string name; public string Name { get { return this.name; } set { this.name = value; FirePropertyChanged(p =&gt; p.Name); } } private void FirePropertyChanged&lt;TValue&gt;(Expression&lt;Func&lt;Person, TValue&gt;&gt; propertySelector) { if (PropertyChanged == null) return; var memberExpression = propertySelector.Body as MemberExpression; if (memberExpression == null) return; PropertyChanged(this, new PropertyChangedEventArgs(memberExpression.Member.Name)); } public event PropertyChangedEventHandler PropertyChanged; } </code></pre> <p>Notice the use of the expression tree to get the name of the property, and the use of the lambda expression as an <code>Expression</code> :</p> <pre><code>FirePropertyChanged(p =&gt; p.Name); </code></pre>
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    1. POINotifyPropertyChanged property name - hardcode vs reflection?
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    1. USRomain Verdier
    1. USRomain Verdier
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    1. COThis seems like overkill for a problem of property changing. While it maintains everything in refactorable code, you end up with a lot more code to maintain and that code is less readable than the original concept of OnPropertyChanged("Name") or a similar method.
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      1. USOrion Adrian
    2. CO+1 for explaining and confirming that "the subscriber of this event is likely to use reflection by calling, for instance, GetProperty". I was wondering what happened after the data object did OnPropertyChanged("Name").
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    3. COVery cool. Is there any way to avoid using strings completely do you think?
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      1. USstrongriley
 

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