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copied!<p>I would start with modeling the interesting operations. Ultimately you will connect them to a UI, but that is the steering wheel and gas pedal, not the engine.</p> <p>What you are attempting to build has a lot in common with programming languages: variables, values, types, expressions, evaluation, etc. Many of the metaphors are applicable and might provide some guidance.</p> <p>If you are using .NET 3.5, you have the option of <a href="http://msdn.microsoft.com/en-us/library/bb397951.aspx" rel="nofollow noreferrer">Expression Trees</a>, which allow you to represent and compile code expressions at runtime.</p> <p>For example, to model your first goal:</p> <pre><code>using System.Linq.Expressions; ConstantExpression theNumber2 = Expression.Constant(2); ConstantExpression theNumber3 = Expression.Constant(3); BinaryExpression add2And3 = Expression.Add(theNumber2, theNumber3); </code></pre> <p>To invoke the expression, we need to wrap <code>add2And3</code> with a method. This is done with a lambda expression:</p> <pre><code>Expression<Func<int>> add2And3Lambda = Expression.Lambda<Func<int>>(add2And3); </code></pre> <p><code>Func<int></code> represents a method which takes no parameters and returns an <code>int</code>. In C#, the code represented by <code>add2And3Lambda</code> would be:</p> <pre><code>() => 2 + 3 </code></pre> <p>So what we have is an expression tree whose root is a method. Because a method is <em>callable</em>, we can compile the tree into an instance of the underlying delegate type:</p> <pre><code>Func<int> add2And3Func = add2And3Lambda.Compile(); </code></pre> <p>Now we can invoke the code we built:</p> <pre><code>int theNumber5 = add2And3Func(); </code></pre> <p>Every expression available to .NET languages is supported.</p> <p>Imagine every node in your graph has an <code>Expression</code> associated with it. That might give you an idea of the power of expression trees and how they could help you with this task.</p>

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