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    <p><strong>Edit</strong></p> <p>I'm glad my answer helped a bit, let me update it slightly further. To use your question as a direct answer, all you would need to change is your field declaration from:</p> <pre><code>Person x = new Person(); </code></pre> <p>to</p> <pre><code>IPerson x = new Person(); </code></pre> <p>Your code-behind now know the properties and methods that are specified in your interface, and is a lot less coupled, as you could swap out <code>new Person()</code> for <code>new Student()</code> later-on. As long as the object implements the interface. <strong>Your code-behind should now work without any necessary changes.</strong></p> <p><em><strong>Side note</em></strong></p> <p>I would recommend considering lazy-loading the <code>x</code> person, and also using a property with a more recognisable name. N.B. this doesn't answer your question, but it's just a suggestion. :)</p> <pre><code>private IPerson _CurrentPerson = null; private IPerson CurrentPerson { get { if (this._CurrentPerson == null) { this._CurrentPerson = new Person(); } return this._CurrentPerson } set { this._CurrentPerson = value; } } </code></pre> <hr> <p>De-coupling is when two, or more, code blocks should not depend on each other. Inversion of Control is when the coupling of objects is bound at runtime, thus allowing for much more flexibility, and therefore less coupling, of objects and their instances. Inversion of control is best use in conjunction with interfaces. The interfaces define that <code>ClassA</code> will do <code>MethodX</code> and have <code>PropertyY</code>. Our main object does not care what object is returned at run-time, as log as it can fulfil an interface, it's happy.</p> <p>In your above example, you will want to interface your person class, maybe something like so:</p> <pre><code>public interface IPerson { string Name { get; set; } string PersonAddText(string text); } public class Person : IPerson { // your code here } </code></pre> <p>Then, within your main method calls, instead of explicitly using a <code>Person</code> object, you will use an instance of an object that implements the interface <code>IPerson</code>. The "hooking" up of the interface and the object can be achieved by various different libraries which will help in setting up your dependencies. In my experience I've used <a href="http://docs.structuremap.net/" rel="nofollow">StructureMap</a> and <a href="http://msdn.microsoft.com/en-us/library/ff648951.aspx" rel="nofollow">Microsoft's Enterprise Library</a>. They can be a bit fiddly to set-up, but once they are, you'll be able to do something like so...</p> <pre><code>public void MainMethod_InInterfaceLayer() { // container is an instance of UnityContainer Person newPerson = container.Resolve&lt;IPerson&gt;(); } </code></pre> <p>I know this ins't a full answer, but hopefully it'll help a bit. :)</p>
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    1. COSo far this answer seems the easiest to understand. I am currently playing around with it and will get back to you. The only problem I am having is the links you provided get into a lot of dept quite quickly and for this simple example, understanding is more important. I would award you the answer if you can write the code needed without the extensions instead of the MainMethod_InInterfaceLayer(). Perhaps by changing what I should do in the MainWindow code behind if possible. Thanks for your help so far.
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    2. COI've updated my answer. Hopefully, in conjunction to @Oded's answer, it should be what you're looking for.
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    3. COThanks Richard. I am just implementing your answer now and the explanation behind it is very nice. I am going to assume that my example is too simple for it to reduce Visual Studios Coupling mark from 3 to 2 on the methods mentioned. As explained in my edits, no reduction happens when I do as you described. Thanks for your help with this. I will play with your side note too, but I have a feeling this is somewhat unrelated (although I appreicate the suggestion). I would like to know the benifit of lazy loading in this case and what line of taught baught you to suggesting it if you have time.
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