Fwd: Anyone ever considered named tuples?

[Paulo Levi]

---------- Forwarded message ----------
From: Paulo Levi <i30817 at gmail.com>
Date: Mon, Mar 23, 2009 at 7:32 PM
Subject: Re: Anyone ever considered named tuples?
To: Marek Kozieł <develop4lasu at gmail.com>


I don't think that maps or arrays are a good way to get effect. I'm saying
that's how people get the effect without thinking about it too much.

Also Neil, i thought "structural types" were a general abstraction of
tuples. Much more powerful i agree, especially if they can be used as method
arguments.

This is how i get the effect when i want to, but meaningless names make me
not use it. Also the places where they might be used are often better off
refactored - one return value is always best, expect in performance critical
iterations:
package util;

import java.io.IOException;
import java.io.Serializable;

/**
 * Type safe, inmutable, tuple classes
 * can be serialized with xmlencoder (>=1.6)
 * or objectoutputstream.
 *
 * Whenever you need to create public api,
 * it is best not to use these classes since the
 * given names (first, second, etc) are not descriptive.
 * @author i30817
 */
public final class Tuples {

    private Tuples() {
    }

    public static <X> T1<X> createSingleton(X target) {
        return new T1<X>(target);
    }

    public static <X, Y> T2<X, Y> createPair(X target1, Y target2) {
        return new T2<X, Y>(target1, target2);
    }

    public static <X, Y, Z> T3<X, Y, Z> createTriple(X target1, Y target2, Z
target3) {
        return new T3<X, Y, Z>(target1, target2, target3);
    }

    public static <W, X, Y, Z> T4<W, X, Y, Z> createQuadruple(W target1, X
target2, Y target3, Z target4) {
        return new T4<W, X, Y, Z>(target1, target2, target3, target4);
    }

    public static final class T1<X> implements Serializable {

        private static final long serialVersionUID = 362498860763181265L;
        private X first;

        //@java.beans.ConstructorProperties({"first"})
        private T1(X first) {
            this.first = first;
        }

        public X getFirst() {
            return first;
        }

        @Override
        public String toString() {
            return "(" + first.toString() + ")";
        }

        @SuppressWarnings(value = "unchecked")
        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final T1<X> other = (T1<X>) obj;
            if (this.first != other.first && (this.first == null ||
!this.first.equals(other.first))) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            int hash = 5;
            hash = 97 * hash + (this.first != null ? this.first.hashCode() :
0);
            return hash;
        }

        private void writeObject(java.io.ObjectOutputStream out) throws
IOException {
            out.writeObject(first);
        }

        @SuppressWarnings(value = "unchecked")
        private void readObject(java.io.ObjectInputStream in) throws
IOException, ClassNotFoundException {
            first = (X) in.readObject();
        }
    }

    public static final class T2<X, Y> implements Serializable {

        private static final long serialVersionUID = 463498820763161265L;
        private X first;
        private Y second;

        //@java.beans.ConstructorProperties({"first","second"})
        private T2(X first, Y second) {
            this.first = first;
            this.second = second;
        }

        public X getFirst() {
            return first;
        }

        public Y getSecond() {
            return second;
        }

        @Override
        public String toString() {
            return "(" + first.toString() + ", " + second.toString() + ")";
        }

        @SuppressWarnings(value = "unchecked")
        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final T2<X, Y> other = (T2<X, Y>) obj;
            if (this.first != other.first && (this.first == null ||
!this.first.equals(other.first))) {
                return false;
            }
            if (this.second != other.second && (this.second == null ||
!this.second.equals(other.second))) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            int hash = 3;
            hash = 67 * hash + (this.first != null ? this.first.hashCode() :
0);
            hash = 67 * hash + (this.second != null ? this.second.hashCode()
: 0);
            return hash;
        }

        private void writeObject(java.io.ObjectOutputStream out) throws
IOException {
            out.writeObject(first);
            out.writeObject(second);
        }

        @SuppressWarnings(value = "unchecked")
        private void readObject(java.io.ObjectInputStream in) throws
IOException, ClassNotFoundException {
            first = (X) in.readObject();
            second = (Y) in.readObject();
        }
    }

    public static final class T3<X, Y, Z> implements Serializable {

        private static final long serialVersionUID = 162498830763481765L;
        private X first;
        private Y second;
        private Z third;

        //@java.beans.ConstructorProperties({"first","second","third"})
        private T3(X first, Y second, Z third) {
            this.first = first;
            this.second = second;
            this.third = third;
        }

        public X getFirst() {
            return first;
        }

        public Y getSecond() {
            return second;
        }

        public Z getThird() {
            return third;
        }

        @Override
        public String toString() {
            return "(" + first.toString() + ", " + second.toString() + ", "
+ third.toString() + ")";
        }

        @SuppressWarnings(value = "unchecked")
        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final T3<X, Y, Z> other = (T3<X, Y, Z>) obj;
            if (this.first != other.first && (this.first == null ||
!this.first.equals(other.first))) {
                return false;
            }
            if (this.second != other.second && (this.second == null ||
!this.second.equals(other.second))) {
                return false;
            }
            if (this.third != other.third && (this.third == null ||
!this.third.equals(other.third))) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            int hash = 7;
            hash = 71 * hash + (this.first != null ? this.first.hashCode() :
0);
            hash = 71 * hash + (this.second != null ? this.second.hashCode()
: 0);
            hash = 71 * hash + (this.third != null ? this.third.hashCode() :
0);
            return hash;
        }

        private void writeObject(java.io.ObjectOutputStream out) throws
IOException {
            out.writeObject(first);
            out.writeObject(second);
            out.writeObject(third);
        }

        @SuppressWarnings(value = "unchecked")
        private void readObject(java.io.ObjectInputStream in) throws
IOException, ClassNotFoundException {
            first = (X) in.readObject();
            second = (Y) in.readObject();
            third = (Z) in.readObject();
        }
    }

    public static final class T4<W, X, Y, Z> implements Serializable {

        private static final long serialVersionUID = 162498830763581765L;
        private W first;
        private X second;
        private Y third;
        private Z fourth;


//@java.beans.ConstructorProperties({"first","second","third","fourth"})
        private T4(W first, X second, Y third, Z fourth) {
            this.first = first;
            this.second = second;
            this.third = third;
            this.fourth = fourth;
        }

        public W getFirst() {
            return first;
        }

        public X getSecond() {
            return second;
        }

        public Y getThird() {
            return third;
        }

        public Z getFourth() {
            return fourth;
        }

        @Override
        public String toString() {
            return "(" + first.toString() + ", " + second.toString() + ", "
+ third.toString() + ", " + fourth.toString() + ")";
        }

        @SuppressWarnings(value = "unchecked")
        @Override
        public boolean equals(Object obj) {
            if (obj == null) {
                return false;
            }
            if (getClass() != obj.getClass()) {
                return false;
            }
            final T4<W, X, Y, Z> other = (T4<W, X, Y, Z>) obj;
            if (this.first != other.first && (this.first == null ||
!this.first.equals(other.first))) {
                return false;
            }
            if (this.second != other.second && (this.second == null ||
!this.second.equals(other.second))) {
                return false;
            }
            if (this.third != other.third && (this.third == null ||
!this.third.equals(other.third))) {
                return false;
            }
            if (this.fourth != other.fourth && (this.fourth == null ||
!this.fourth.equals(other.fourth))) {
                return false;
            }
            return true;
        }

        @Override
        public int hashCode() {
            int hash = 5;
            hash = 29 * hash + (this.first != null ? this.first.hashCode() :
0);
            hash = 29 * hash + (this.second != null ? this.second.hashCode()
: 0);
            hash = 29 * hash + (this.third != null ? this.third.hashCode() :
0);
            hash = 29 * hash + (this.fourth != null ? this.fourth.hashCode()
: 0);
            return hash;
        }

        private void writeObject(java.io.ObjectOutputStream out) throws
IOException {
            out.writeObject(first);
            out.writeObject(second);
            out.writeObject(third);
            out.writeObject(fourth);
        }

        @SuppressWarnings(value = "unchecked")
        private void readObject(java.io.ObjectInputStream in) throws
IOException, ClassNotFoundException {
            first = (W) in.readObject();
            second = (X) in.readObject();
            third = (Y) in.readObject();
            fourth = (Z) in.readObject();
        }
    }
}