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    <p>Design patterns express ideas in a general sense and not a specific class hierarchy that should be used to implement the pattern. In C#, you wouldn't implement the idea using classes and interfaces (as for example in Java), because it provides a more straightforward solution. You can use <strong>events</strong> and <strong>delegates</strong> instead. Here is a nice article that you may want to check out:</p> <ul> <li><a href="http://blogs.msdn.com/b/bashmohandes/archive/2007/03/10/observer-pattern-in-c-events-delegates.aspx" rel="nofollow noreferrer">Observer pattern in C# = Events + delegates</a></li> </ul> <p>Note that observer isn't the only pattern that can be encoded far more elegantly in C#. For example the Strategy pattern can be implemented using (single-line) lambda expression in C#:</p> <ul> <li><a href="http://www.unboxedsolutions.com/sean/archive/2005/10/23/779.aspx" rel="nofollow noreferrer">Strategy Pattern: Today, Tomorrow, and C# 3.0</a> </li> </ul> <p>That said, I'm quite sceptical about design patterns in many ways, but they may be useful as a reference. However they shouldn't be used blindly. Some authors maybe think that following the pattern strictly is the only way to write quality "enterprise" software, but that's not the case!</p> <p><strong>EDIT</strong> Here is a succinct version of your Ruby code. I didn't read the C# version, because it is too complex (and I'd even say obfuscated):</p> <pre><code>class Employee { public Employee(string name, string address, int salary) { Name = name; Address = address; this.salary = salary; } private int salary; public event Action&lt;Employee&gt; SalaryChanged; public string Name { get; set; } public string Address { get; set; } public int Salary { get { return salary; } set { salary = value; if (SalaryChanged != null) SalaryChanged(this); } } var fred = new Employee(...); fred.SalaryChanged += (changed_employee) =&gt; Console.WriteLine("Send {0} a new tax bill!", changed_employee.Name); </code></pre> <p>This is a perfectly fine use of events &amp; delegates. C# 3.0 lambda functions make your example even simpler than in Ruby :-).</p>
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    1. POWhy Observer pattern is much more complicated in C# than in Ruby?
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    1. USTomas Petricek
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    1. CODeisgn patterns are useful as a language to communicate common solutions to other programmers. They're not as useful when it comes to providing pre-canned solutions.
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      1. USMichael Meadows
    2. COConcerning your first article (http://spellcoder.com/blogs/bashmohandes/archive/2007/03/10/6212.aspx) I still don't see the reason to use delegates and events, they make code more difficult to understand.
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      1. USrobert_d
    3. CO[Extreme sceptic note:] Are they really useful for communicating common solutions? Doesn't this SO question show that they fail to do that? I do agree in principle, but it gets complicated when more and more languages have much better ways for encoding the pattern. Then design patterns can become counterproductive, because they take you away from the straightforward solution. Design patterns would be great if _everyone_ who is writing about them would be aware of this issue.
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