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Bil Lewis

Dr. Dobb's Bloggers

My *New* Favorite Anti-Pattern

September 30, 2009

Programming Pattern == A Template for a good way of doing things well.
Anti-Pattern == A Template for a good way of doing things poorly. :-)

This is closely related to the previous post.

As I was working on some code, I ran over this method (details changed
to protect the guilty):

public Object resolveSession(Object obj, String returnType) {
  if (Obj instanceof String) {
    if (returnType.equals("String"))
      return obj;
    if (returnType.equals("Session"))
      return new DbSession((String) obj);
    if (returnType.equals("Context"))
      return new DbContext((String) obj);
    }

  if (Obj instanceof DbSession) {
    if (returnType.equals("String"))
      return ((DbSession) obj).getDbName();
    if (returnType.equals("Session"))
      return obj;
    if (returnType.equals("Context"))
      return new DbContext(((DbSession) obj).getDbName());
    }

  if (Obj instanceof DbContext) {
    if (returnType.equals("String"))
      return ((DbContext) obj).getDbSession().getDbName();
    if (returnType.equals("Session"))
      return ((DbContext) obj).getDbSession();
    if (returnType.equals("Context"))
      return new obj;
    }
throw new RuntimeException("Bad input"); 
}


I suspect this was written with Python in mind, but it's not that
important. What's important is that it's useful and readable.

So... is it?

Is this:

Object dbAlias = "test";
DbSession session = (DbSession) resolveSession(dbAlias, "Session");
DbContext context = (DbContext) resolveSession(session, "Context");


better than this:

String dbAlias = "test";
DbSession session = new DbSession(dbAlias);
DbContext context = new DbContext(session.getDbName());

?

How much difference would it make if this were in Python? 

 How do you write your code? 

-Bil

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