
Scala example source code file (Ordered.scala)
The Ordered.scala Scala example source code/* __ *\ ** ________ ___ / / ___ Scala API ** ** / __/ __// _  / / / _  (c) 20032013, LAMP/EPFL ** ** __\ \/ /__/ __ / /__/ __  http://scalalang.org/ ** ** /____/\___/_/ _/____/_/   ** ** / ** \* */ package scala package math import scala.language.implicitConversions /** A trait for data that have a single, natural ordering. See * [[scala.math.Ordering]] before using this trait for * more information about whether to use [[scala.math.Ordering]] instead. * * Classes that implement this trait can be sorted with * [[scala.util.Sorting]] and can be compared with standard comparison operators * (e.g. > and <). * * Ordered should be used for data with a single, natural ordering (like * integers) while Ordering allows for multiple ordering implementations. * An Ordering instance will be implicitly created if necessary. * * [[scala.math.Ordering]] is an alternative to this trait that allows multiple orderings to be * defined for the same type. * * [[scala.math.PartiallyOrdered]] is an alternative to this trait for partially ordered data. * * For example, create a simple class that implements `Ordered` and then sort it with [[scala.util.Sorting]]: * {{{ * case class OrderedClass(n:Int) extends Ordered[OrderedClass] { * def compare(that: OrderedClass) = this.n  that.n * } * * val x = Array(OrderedClass(1), OrderedClass(5), OrderedClass(3)) * scala.util.Sorting.quickSort(x) * x * }}} * * It is important that the `equals` method for an instance of `Ordered[A]` be consistent with the * compare method. However, due to limitations inherent in the type erasure semantics, there is no * reasonable way to provide a default implementation of equality for instances of `Ordered[A]`. * Therefore, if you need to be able to use equality on an instance of `Ordered[A]` you must * provide it yourself either when inheriting or instantiating. * * It is important that the `hashCode` method for an instance of `Ordered[A]` be consistent with * the `compare` method. However, it is not possible to provide a sensible default implementation. * Therefore, if you need to be able compute the hash of an instance of `Ordered[A]` you must * provide it yourself either when inheriting or instantiating. * * @see [[scala.math.Ordering]], [[scala.math.PartiallyOrdered]] * @author Martin Odersky * @version 1.1, 20060724 */ trait Ordered[A] extends Any with java.lang.Comparable[A] { /** Result of comparing `this` with operand `that`. * * Implement this method to determine how instances of A will be sorted. * * Returns `x` where: * *  `x < 0` when `this < that` * *  `x == 0` when `this == that` * *  `x > 0` when `this > that` * */ def compare(that: A): Int /** Returns true if `this` is less than `that` */ def < (that: A): Boolean = (this compare that) < 0 /** Returns true if `this` is greater than `that`. */ def > (that: A): Boolean = (this compare that) > 0 /** Returns true if `this` is less than or equal to `that`. */ def <= (that: A): Boolean = (this compare that) <= 0 /** Returns true if `this` is greater than or equal to `that`. */ def >= (that: A): Boolean = (this compare that) >= 0 /** Result of comparing `this` with operand `that`. */ def compareTo(that: A): Int = compare(that) } object Ordered { /** Lens from `Ordering[T]` to `Ordered[T]` */ implicit def orderingToOrdered[T](x: T)(implicit ord: Ordering[T]): Ordered[T] = new Ordered[T] { def compare(that: T): Int = ord.compare(x, that) } } Other Scala source code examplesHere is a short list of links related to this Scala Ordered.scala source code file: 
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