org.scalautils

DecidedByEquality

class DecidedByEquality [A] extends Equality[A]

Defines a custom way to determine equality for a type.

For example, here's how you could define equality between Doubles such that a tolerance of ± 0.01 is allowed:

class TolerantDoubleEquality extends Equality[Double] {

private val Tol = 0.01

def areEqual(a: Double, b: Any): Boolean = { b match { case bDouble: Double => (a <= bDouble + Tol) && (a >= bDouble - Tol) case _ => false } } }

If an implicit instance of TolerantDoubleEquality is in scope, it will be used by ScalaTest's === operators and its should equal and should === matcher syntax. Here's an example:

$ scala -cp target/jar_contents/
Welcome to Scala version 2.10.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.6.0_33).
Type in expressions to have them evaluated.
Type :help for more information.

scala> import org.scalautils._ import org.scalautils._

scala> class TolerantDoubleEquality extends Equality[Double] { | | private val Tol = 0.01 | | def areEqual(a: Double, b: Any): Boolean = { | b match { | case bDouble: Double => (a >= bDouble + Tol) && (a >= bDouble - Tol) | case _ => false | } | } | } defined class TolerantDoubleEquality

scala> import TripleEquals._ import TripleEquals._

scala> 2.0 === 2.001 res0: Boolean = false

scala> implicit val tolerantDoubleEquality = new TolerantDoubleEquality tolerantDoubleEquality: TolerantDoubleEquality = TolerantDoubleEquality@70c13c17

scala> 2.0 === 2.001 res1: Boolean = true

Note: The Equality type class was inspired in part by the Equal type class of the scalaz project.

A

the type whose equality is being customized

Linear Supertypes
Equality[A], AnyRef, Any
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  1. DecidedByEquality
  2. Equality
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Instance Constructors

  1. new DecidedByEquality (equality: Equality[A])

Value Members

  1. def != (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  2. def != (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any
  3. def ## (): Int

    Attributes
    final
    Definition Classes
    AnyRef → Any
  4. def == (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  5. def == (arg0: Any): Boolean

    Attributes
    final
    Definition Classes
    Any
  6. def afterBeing (normalization: Normalization[A]): NormalizingEquality[A]

  7. def areEqual (a: A, b: Any): Boolean

    Indicates whether the objects passed as a and b are equal.

    Indicates whether the objects passed as a and b are equal.

    a

    a left-hand-side object being compared with another (right-hand-side one) for equality (e.g., a == b)

    b

    a right-hand-side object being compared with another (left-hand-side one) for equality (e.g., a == b)

    returns

    true if the passed objects are "equal," as defined by this Equality instance

    Definition Classes
    DecidedByEqualityEquality
  8. def asInstanceOf [T0] : T0

    Attributes
    final
    Definition Classes
    Any
  9. def clone (): AnyRef

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  10. def eq (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  11. def equals (arg0: Any): Boolean

    Definition Classes
    AnyRef → Any
  12. def finalize (): Unit

    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws()
  13. def getClass (): java.lang.Class[_]

    Attributes
    final
    Definition Classes
    AnyRef → Any
  14. def hashCode (): Int

    Definition Classes
    AnyRef → Any
  15. def isInstanceOf [T0] : Boolean

    Attributes
    final
    Definition Classes
    Any
  16. def ne (arg0: AnyRef): Boolean

    Attributes
    final
    Definition Classes
    AnyRef
  17. def notify (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
  18. def notifyAll (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
  19. def synchronized [T0] (arg0: ⇒ T0): T0

    Attributes
    final
    Definition Classes
    AnyRef
  20. def toString (): String

    Definition Classes
    AnyRef → Any
  21. def wait (): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()
  22. def wait (arg0: Long, arg1: Int): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()
  23. def wait (arg0: Long): Unit

    Attributes
    final
    Definition Classes
    AnyRef
    Annotations
    @throws()

Inherited from Equality[A]

Inherited from AnyRef

Inherited from Any