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POWhat are some good design patterns for copying an object?
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copied!<p>I need to copy an object that has a pretty deep hierarchy of member variables (i.e., the object has several members of various types, each of which has several members of various types, etc.). Doing a deep copy would require implementing a clone() method in many classes, which seems overkill for my application.</p> <p>The solution I've come up with is fairly simple, but I wonder if it's a bad idea. My solution is as follows:</p> <ul> <li>Define an empty interface, <code>Settings</code>.</li> <li>Define an interface called <code>IsCopyable</code>, which has methods <code>getSettings()</code> and <code>applySettings(Settings s)</code>.</li> <li>For a given class <code>X</code> that implements <code>IsCopyable</code>, a class that implements the interface <code>Settings</code> is written that holds the 'settings' that must be applied to an object of class <code>X</code> in order to copy it. (I usually nest this class within the class <code>X</code>, so I have <code>X.Settings implements Settings</code>, but this could be done elsewhere.)</li> </ul> <p>Then, to copy an instance of class X:</p> <pre><code>X myX = new X(); // Stuff happens to myX. // Now we want to copy myX. X copyOfX = new X(); copyOfX.applySettings(myX.getSettings()); </code></pre> <p>I.e., to copy a given object, create a new instance of that object, then call <code>getSettings()</code> on the object to be copied, passing the resulting <code>Settings</code> object as a value to <code>applySettings()</code> on the new instance. (Of course, the copying could be wrapped in a member called copy() or something.)</p> <p>This works very well for my particular problem, but am I doing something stupid? Have I (poorly) reinvented something that already exists?</p> <p>Thanks in advance.</p> <p>Chris</p>

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