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From: pcb@cacs.usl.edu (Peter C. Bahrs)
Newsgroups: comp.object
Subject: Re: Do we really need types in OOPL's?
Message-ID: <15362@rouge.usl.edu>
Date: 26 Sep 90 16:40:02 GMT
Sender: anon@rouge.usl.edu
Organization: The Center for Advanced Computer Studies, USL
Lines: 43


Without being for or against, how do you implement polymorphism without types?

  For instance in OO|| syntax:

   Class A;
   A.(behavior x);
   A.(behavior y);

st. x and y are different objects.  How can you tell the difference?

In C++ or OO|| you would define 
    behavior (Classname id);
    behavior (Classname2 id);
and the compiler or interpreter will invoke the correct behavior/method based
on the class of the incoming objects.  Otherwise each behavior
must contain added code looking like a switch statement:
     behavior (id)
     {
        if ( (id.(class)).(== "Classname") )
          {
           /* do this */
          }
        else 
         {
          if ( (id.(class)).(== "Classname2") )
          ...
         }
      }

This approach adds more complexity to the code.  It is compounded even more
with variable number of arguments.  

Just a thought.

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| Peter C. Bahrs                                                         |
| The USL-NASA Project                                                   |
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