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PODatabinding phenomenon in WPF (binding to a FrameworkElement) - any ideas why?
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copied!<p>In an application of mine (this has to do with very dynamic navigation and content presentation) I have to use this construct in XAML:</p> <pre><code><ContentControl Content={Binding ContentElement} /> </code></pre> <p>So far, so good. This is great, absolutely great. I can host arbitrary stuff all over the place.</p> <p>But there seems to be a strange, well, lets call it "phenomenon" in WPF (I believe it is in the BindingMarkupExtension, but not sure yet):</p> <p>When my ContentElement property looks like this:</p> <pre><code>public FrameworkElement ContentElement { get { return this.m_ContentElement; } } </code></pre> <p>then the getter gets called TWICE (!!!) for each databinding operation (this includes when the user changes the language on the fly or reloads the hosting control).</p> <p>However (and this is what is REALLY mind boggling for me):</p> <p>When I change my ContentElement property to:</p> <pre><code>public object ContentElement { get { return this.m_ContentElement; } } </code></pre> <p>then the getter gets called once. Seriously, I'm not lying here. It is absolutely reproducible in the simplest applications, you can try for example by returning a new "TextBlock" (thats what I usually do to test or learn about more advanced WPF concepts).</p> <p>Any ideas why?</p> <p>The reason why I ask is that I hate the following consequences of the solution:</p> <ul> <li>I lose type safety at this point</li> <li>This may be a bit hard to explain to new developers or overly sceptical wisecracks</li> </ul>

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