multiply1(this@Real, other@Real) =

multiply1(Real this, Real other) =

multiply1(this@Integer, other@Integer) =

multiply1(Integer this, Integer other) =

multiply1(this@Integer, other@Rational) =

multiply1(Integer this, Rational other) =

multiply1(this@Rational, other@Integer) =

multiply1(Rational this, Integer other) =

multiply1(this@Rational, other@Rational) =

multiply1(Rational this, Rational other) =

%META:TOPICINFO{author="IsaacGouy" date="1064012340" format="1.0" version="1.1"}% %META:TOPICPARENT{name="CodeExamples"}% The original MultiJava code for this benchmark, and the Java comparison code, is available from this Technical Report: "MultiJava: Design, implementation, and evaluation of a Java-compatible language supporting modular open classes and symmetric multiple dispatch", Curtis Clifton, Iowa State University TR #01-10, November 2001.
ftp://ftp.cs.iastate.edu/pub/techreprts/TR01-10/TR.pdf

Curtis Clifton kindly gave permission for this use.

The performance ratios for MultiJava and Nice are very different - the results are from different machines, and different test iterations but that doesn't seem like an adequate explanation.

Multiple Dispatch

The typecases and double-dispatch implementations are given in the MultiJava report. A single line was changed in both of the Java test driver classes Exercise.java and TestMultipleDispatch.java (to call the Nice multi-dispatch method):

Real result = values[i].multiply1(values[j]);

Real result = dispatch.multiply1(values[i],values[j]);

The multi-dispatch methods were placed together in a separate file. That is different to the MultiJava implementation:

// compilation unit multiply1.nice
package multipledispatch;

import multipledispatch.*;

// Methods using multiple dispatch

Real multiply1(Real this, Real other);

multiply1(this@Real, other@Real) = 
   new Real(this.value * other.value());

multiply1(this@Integer, other@Integer) = 
   new Integer(lValue * other.getLValue() );

multiply1(this@Integer, other@Rational) = 
   new Rational(lValue * other.numerator(), other.denominator() );

multiply1(this@Rational, other@Integer) =
   new Rational( this.numerator * other.getLValue(), 
                 this.denominator ); 

multiply1(this@Rational, other@Rational) =
   new Rational( this.numerator * other.numerator(), 
                 this.denominator * other.denominator() );
   
long getLValue(Integer) = native long multipledispatch.Integer.lValue();

-- IsaacGouy - 19 Sep 2003