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POHow to handle static fields that vary by implementing class
 

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    <p>I hit this problem all the time. Suppose I am making a command line interface (Java or C#, the problem is the same I think, I will show C# here).</p> <ol> <li>I define an interface ICommand</li> <li>I create an abstract base class CommandBase which implements ICommand, to contain common code.</li> <li>I create several implementation classes, each extending the base class (and by extension the interface).</li> </ol> <p>Now - suppose that the interface specifies that all commands implement the Name property and the Execute method...</p> <p>For Name each of my instance classes must return a string that is the name of that command. That string ("HELP", "PRINT" etc) is static to the class concerned. What I would love to be able to do is define:</p> <p>public abstract static const string Name;</p> <p>However (sadly) you cannot define static members in an interface.</p> <p>I have struggled with this issue for years now (pretty much any place I have a family of similar classes) and so will post my own 3 possible solutions below for your votes. However since none of them is ideal I am hoping someone will post a more elegant solution.</p> <hr> <p>UPDATE:</p> <ol> <li>I can't get the code formatting to work properly (Safari/Mac?). Apologies.</li> <li><p>The example I am using is trivial. In real life there are sometimes dozens of implementing classes and several fields of this semi-static type (ie static to the implementing class).</p></li> <li><p>I forgot to mention - ideally I want to be able to query this information statically:</p> <p>string name = CommandHelp.Name;</p></li> </ol> <p>2 of my 3 proposed solutions require that the class be instantiated before you can find out this static information which is ugly.</p>
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