title: abstract class extends abstract class in php?
body: <p>I am working on a simple abstract database class. In my usage of this class, I'll want to have some instance be a singleton. I was thinking of having a abstract class that is <em>not</em> a singleton, and then extend it into another abstract class  that <em>is</em> a singleton. Is this possible? Recommended?</p>
  
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  <p>Edit: I want to have two abstract that are practically identical, except one is a singleton. So the only difference will be that one will have all the functions of the other, but will have the other properties and methods that make it behave like a singleton. </p>
  
  <p>I'd like to have one base class code base for this so as I make changes, I don't have to keep two files in sync. </p>