Q: Multidispatch semantic

To: info-dylan@ai.mit.edu
Subject: Q: Multidispatch semantic
From: "Samuele Pedroni" <pedroni@inf.ethz.ch>
Date: Fri, 13 Jul 2001 21:45:01 -0400 (EDT)
Organization: Swiss Federal Institute of Technology (ETHZ)
Xref: traf.lcs.mit.edu comp.lang.dylan:13476

Hi. I have tried the following program. After reading the DRM 6. Functions-
Method Dispatch I would have expected
some kind of ambiguity error, the results that I get with FunDev are just
like CLOS multidispatch. Argument order counts.
What I'm missing? Thanks Samuele Pedroni.

Module: hello2

define class <panel> (<object>)
end class <panel> ;

define class <pad-panel> (<panel>)
end class <pad-panel> ;

define class <specific> (<object>)
end class <specific> ;

define method present (panel :: <panel> , obj :: <object>)
format-out("generic panel present");
end method present;

define method present (panel :: <pad-panel>, obj :: <object> )
format-out("pad present");
end method present;

define method present (panel :: <panel> , obj :: <specific>  )
format-out("generic panel <specific> present");
end method present;

define method present2 (obj :: <object> , panel :: <panel> )
format-out("generic panel present(2)");
end method present2;
define method present2 (obj :: <object> , panel :: <pad-panel> )
format-out("pad present(2)");
end method present2;

define method present2 (obj :: <specific> , panel :: <panel>  )
format-out("generic panel <specific> present(2)");
end method present2;

define method main () => ()
  let pad = make(<pad-panel>);
  let obj = make(<specific>);
  present(pad,obj) ;
  format-out("\n");
  present2(obj,pad) ;
end method main;

/* Output:
   pad present
   generic panel <specific> present(2)

given the rules in DRM 6. Functions - Method Dispatch
I would have expected an ambiguity error in both cases.
*/

begin
  main();
end;

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Re: Multidispatch semantic

From: "Scott McKay" <swm@mediaone.net>