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POHow to expose properties of a user control in .NET for the MVP pattern
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copied! <p>I am implementing a simple <code>UserControl</code> that is actually a fancy <code>TextBox</code>. One of its features is that you can set a formatting specification and this formatting get's applied to its contents automatically. For example, if you set the formatting specification to <code>"000"</code> and the contents are <code>"42"</code>, then <code>"042"</code> will appear.</p> <p>I am implementing this <code>UserControl</code> following the MVP pattern. The implementation is similar to this: <a href="https://stackoverflow.com/questions/7606955/how-implement-usercontrol-in-winforms-mvp-pattern/7607697#7607697">how Implement usercontrol in winforms mvp pattern?</a>. Also, check this question: <a href="https://stackoverflow.com/questions/2668673/passive-view-and-display-logic">passive view and display logic</a></p> <h2>Approach #1</h2> <p>My <code>Title</code> property in the <code>View</code> looks like this:</p> <pre class="lang-csh prettyprint-override"><code>private string title; public string Title { get { return title; } set { title = value; titleTextBox.Text = presenter.Format(title); } } </code></pre> <p>It is my feeling that this implementation adds unnecessary coupling. For example, if I change the <code>Presenter</code>'s <code>Format</code> method then I will have to go through all <code>View</code>s and change appropriately the call statement.</p> <h2>Approach #2</h2> <p>My <code>Title</code> property in the <code>View</code> looks like this:</p> <pre class="lang-csh prettyprint-override"><code>public string Title { get { return presenter.Title; } set { presenter.Title = value; } } </code></pre> <p>My <code>Title</code> property in the <code>Presenter</code> looks like this:</p> <pre class="lang-csh prettyprint-override"><code>private string title; public string Title { get { return title; } set { _view.SetTitle(this.Format(value); } } </code></pre> <p>Now I have to add the <code>SetTitle</code> method in the <code>View</code> interface and in the <code>View</code> implementation:</p> <pre class="lang-csh prettyprint-override"><code>public void SetTitle(string title) { titleTextBox.Text = title; } </code></pre> <p>So, with this approach I get this ugly <code>SetTitle</code> Java-like method.</p> <h2>Approach #3</h2> <p>Instead of calling <code>SetTitle</code> create a new property <code>RealTitle</code> in the <code>View</code> and set that. It remains ugly with this <code>Real</code> prefix.</p> <h2>Your approach</h2> <p>Can you think of a better way?</p> <h2>Use case</h2> <p>The <code>UserControl</code> should be used like this:</p> <pre class="lang-csh prettyprint-override"><code>var c = new FancyTextBox(); c.Format = "000"; c.Text = "42"; Controls.Add(c); </code></pre> <p>This snippet should display <code>"042"</code> inside the <code>UserControl</code>.</p> <h2>The big picture</h2> <pre class="lang-csh prettyprint-override"><code>Form FancyTextBoxView FancyTextBoxPresenter | | | | ftb.Text = "42" | | |-------------------->| | | | | | | A | | |----------------------------->| | | | | | B | | |<-----------------------------| </code></pre> <p>What are the A and B actions? I want the formatted text to appear in the UI. The formatting code is in the <code>Presenter</code>. The <code>View</code> has a <code>titleTextBox</code> that will hold the text in the UI.</p>

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