trait TripleEquals extends TripleEqualsSupport

Provides === and !== operators that return Boolean, delegate the equality determination to an Equality type class, and require no relationship between the types of the two values compared.

Recommended Usage: Trait TripleEquals is useful (in both production and test code) when you need determine equality for a type of object differently than its equals method: either you can't change the equals method, or the equals method is sensible generally, but you are in a special situation where you need something else. You can use the SuperSafe Community Edition compiler plugin to get a compile-time safety check of types being compared with ===. In situations where you need a stricter type check, you can use TypeCheckedTripleEquals.

This trait will override or hide implicit methods defined by its sibling traits, ConversionCheckedTripleEquals or TypeCheckedTripleEquals, and can therefore be used to temporarily turn of type checking in a limited scope. Here's an example, in which TypeCheckedTripleEquals will cause a compiler error:

import org.scalactic._
import TypeCheckedTripleEquals._

object Example {

  def cmp(a: Int, b: Long): Int = {
    if (a === b) 0       // This line won't compile
    else if (a < b) -1
    else 1
  }

 def cmp(s: String, t: String): Int = {
   if (s === t) 0
   else if (s < t) -1
   else 1
 }
}

Because Int and Long are not in a subtype/supertype relationship, comparing 1 and 1L in the context of TypeCheckedTripleEquals will generate a compiler error:

Example.scala:9: error: types Int and Long do not adhere to the equality constraint selected for
the === and !== operators; they must either be in a subtype/supertype relationship, or, if
ConversionCheckedTripleEquals is in force, implicitly convertible in one direction or the other;
the missing implicit parameter is of type org.scalactic.Constraint[Int,Long]
    if (a === b) 0      // This line won't compile
          ^
one error found

You can “turn off” the type checking locally by importing the members of TripleEquals in a limited scope:

package org.scalactic.examples.tripleequals

import org.scalactic._
import TypeCheckedTripleEquals._

object Example {

  def cmp(a: Int, b: Long): Int = {
    import TripleEquals._
    if (a === b) 0
    else if (a < b) -1
    else 1
  }

 def cmp(s: String, t: String): Int = {
   if (s === t) 0
   else if (s < t) -1
   else 1
 }
}

With the above change, the Example.scala file compiles fine. Type checking is turned off only inside the first cmp method that takes an Int and a Long. TypeCheckedTripleEquals is still enforcing its type constraint, for example, for the s === t expression in the other overloaded cmp method that takes strings.

Because the methods in TripleEquals (and its siblings)override all the methods defined in supertype TripleEqualsSupport, you can achieve the same kind of nested tuning of equality constraints whether you mix in traits, import from companion objects, or use some combination of both.

In short, you should be able to select a primary constraint level via either a mixin or import, then change that in nested scopes however you want, again either through a mixin or import, without getting any implicit conversion ambiguity. The innermost constraint level in scope will always be in force.

Source
TripleEquals.scala
Linear Supertypes
TripleEqualsSupport, AnyRef, Any
Known Subclasses
TripleEquals
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Type Members

  1. class CheckingEqualizer[L] extends AnyRef

    Class used via an implicit conversion to enable two objects to be compared with === and !== with a Boolean result and an enforced type constraint between two object types.

    Class used via an implicit conversion to enable two objects to be compared with === and !== with a Boolean result and an enforced type constraint between two object types. For example:

    assert(a === b)
assert(c !== d)

    You can also check numeric values against another with a tolerance. Here are some examples:

    assert(a === (2.0 +- 0.1))
assert(c !== (2.0 +- 0.1))

    Definition Classes
    TripleEqualsSupport
  2. class Equalizer[L] extends AnyRef

    Class used via an implicit conversion to enable any two objects to be compared with === and !== with a Boolean result and no enforced type constraint between two object types.

    Class used via an implicit conversion to enable any two objects to be compared with === and !== with a Boolean result and no enforced type constraint between two object types. For example:

    assert(a === b)
assert(c !== d)

    You can also check numeric values against another with a tolerance. Here are some examples:

    assert(a === (2.0 +- 0.1))
assert(c !== (2.0 +- 0.1))

    Definition Classes
    TripleEqualsSupport

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. def !==[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]

    Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate the “<left> should !== (<pivot> +- <tolerance>)” syntax of Matchers.

    Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate the “<left> should !== (<pivot> +- <tolerance>)” syntax of Matchers.

    right

    the Spread[T] against which to compare the left-hand value

    returns

    a TripleEqualsInvocationOnSpread wrapping the passed Spread[T] value, with expectingEqual set to false.

    Definition Classes
    TripleEqualsSupport
  3. def !==(right: Null): TripleEqualsInvocation[Null]

    Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate the “<left> should !== null” syntax of Matchers.

    Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate the “<left> should !== null” syntax of Matchers.

    right

    a null reference

    returns

    a TripleEqualsInvocation wrapping the passed null value, with expectingEqual set to false.

    Definition Classes
    TripleEqualsSupport
  4. def !==[T](right: T): TripleEqualsInvocation[T]

    Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate the “<left> should !== <right>” syntax of Matchers.

    Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate the “<left> should !== <right>” syntax of Matchers.

    right

    the right-hand side value for an equality assertion

    returns

    a TripleEqualsInvocation wrapping the passed right value, with expectingEqual set to false.

    Definition Classes
    TripleEqualsSupport
  5. final def ##(): Int
    Definition Classes
    AnyRef → Any
  6. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  7. def ===[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]

    Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate the “<left> should === (<pivot> +- <tolerance>)” syntax of Matchers.

    Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate the “<left> should === (<pivot> +- <tolerance>)” syntax of Matchers.

    right

    the Spread[T] against which to compare the left-hand value

    returns

    a TripleEqualsInvocationOnSpread wrapping the passed Spread[T] value, with expectingEqual set to true.

    Definition Classes
    TripleEqualsSupport
  8. def ===(right: Null): TripleEqualsInvocation[Null]

    Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate the “<left> should === null” syntax of Matchers.

    Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate the “<left> should === null” syntax of Matchers.

    right

    a null reference

    returns

    a TripleEqualsInvocation wrapping the passed null value, with expectingEqual set to true.

    Definition Classes
    TripleEqualsSupport
  9. def ===[T](right: T): TripleEqualsInvocation[T]

    Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate the “<left> should === <right>” syntax of Matchers.

    Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate the “<left> should === <right>” syntax of Matchers.

    right

    the right-hand side value for an equality assertion

    returns

    a TripleEqualsInvocation wrapping the passed right value, with expectingEqual set to true.

    Definition Classes
    TripleEqualsSupport
  10. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  11. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )
  12. def conversionCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], cnv: (B) ⇒ A): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an implicit Equivalence[A].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an implicit Equivalence[A].

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits ConversionCheckedTripleEquals) and overriden as non-implicit by the other subtraits in this package.

    equivalenceOfA

    an Equivalence[A] type class to which the Constraint.areEqual method will delegate to determine equality.

    cnv

    an implicit conversion from B to A

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  13. def convertEquivalenceToAToBConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: <:<[A, B]): CanEqual[A, B]

    Provides a A CanEqual B for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an explicit Equivalence[B].

    Provides a A CanEqual B for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an explicit Equivalence[B].

    This method is used to enable the Explicitly DSL for TypeCheckedTripleEquals by requiring an explicit Equivalance[B], but taking an implicit function that provides evidence that A is a subtype of B.

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits LowPriorityTypeCheckedConstraint (extended by TypeCheckedTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    equivalenceOfB

    an Equivalence[B] type class to which the Constraint.areEqual method will delegate to determine equality.

    ev

    evidence that A is a subype of B

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  14. def convertEquivalenceToAToBConversionConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: (A) ⇒ B): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an explicit Equivalence[B].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an explicit Equivalence[B].

    This method is used to enable the Explicitly DSL for ConversionCheckedTripleEquals by requiring an explicit Equivalance[B], but taking an implicit function that converts from A to B.

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits LowPriorityConversionCheckedConstraint (extended by ConversionCheckedTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  15. def convertEquivalenceToBToAConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: <:<[B, A]): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an explicit Equivalence[A].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an explicit Equivalence[A].

    This method is used to enable the Explicitly DSL for TypeCheckedTripleEquals by requiring an explicit Equivalance[B], but taking an implicit function that provides evidence that A is a subtype of B. For example, under TypeCheckedTripleEquals, this method (as an implicit method), would be used to compile this statement:

    def closeEnoughTo1(num: Double): Boolean =
  (num === 1.0)(decided by forgivingEquality)

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits TypeCheckedTripleEquals) and overriden as non-implicit by the other subtraits in this package.

    ev

    evidence that B is a subype of A

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  16. def convertEquivalenceToBToAConversionConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: (B) ⇒ A): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an explicit Equivalence[A].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an explicit Equivalence[A].

    This method is used to enable the Explicitly DSL for ConversionCheckedTripleEquals by requiring an explicit Equivalance[A], but taking an implicit function that converts from B to A. For example, under ConversionCheckedTripleEquals, this method (as an implicit method), would be used to compile this statement:

    def closeEnoughTo1(num: Double): Boolean =
  (num === 1.0)(decided by forgivingEquality)

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits ConversionCheckedTripleEquals) and overriden as non-implicit by the other subtraits in this package.

    equivalenceOfA

    an Equivalence[A] type class to which the Constraint.areEqual method will delegate to determine equality.

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  17. def convertToCheckingEqualizer[T](left: T): CheckingEqualizer[T]

    Converts to an CheckingEqualizer that provides === and !== operators that result in Boolean and enforce a type constraint.

    Converts to an CheckingEqualizer that provides === and !== operators that result in Boolean and enforce a type constraint.

    This method is overridden and made implicit by subtraits TypeCheckedTripleEquals and ConversionCheckedTripleEquals, and overriden as non-implicit by the other subtraits in this package.

    left

    the object whose type to convert to CheckingEqualizer.

    Definition Classes
    TripleEquals → TripleEqualsSupport
    Exceptions thrown

    NullPointerException if left is null.

  18. implicit def convertToEqualizer[T](left: T): Equalizer[T]

    Converts to an Equalizer that provides === and !== operators that result in Boolean and enforce no type constraint.

    Converts to an Equalizer that provides === and !== operators that result in Boolean and enforce no type constraint.

    This method is overridden and made implicit by subtrait TripleEquals and overriden as non-implicit by the other subtraits in this package.

    left

    the object whose type to convert to Equalizer.

    Definition Classes
    TripleEquals → TripleEqualsSupport
    Exceptions thrown

    NullPointerException if left is null.

  19. def defaultEquality[A]: Equality[A]

    Returns an Equality[A] for any type A that determines equality by first calling .deep on any Array (on either the left or right side), then comparing the resulting objects with ==.

    Returns an Equality[A] for any type A that determines equality by first calling .deep on any Array (on either the left or right side), then comparing the resulting objects with ==.

    returns

    a default Equality for type A

    Definition Classes
    TripleEqualsSupport
  20. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  21. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  22. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  23. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  24. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  25. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  26. def lowPriorityConversionCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], cnv: (A) ⇒ B): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an implicit Equivalence[B].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an implicit Equivalence[B].

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits LowPriorityConversionCheckedConstraint (extended by ConversionCheckedTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    cnv

    an implicit conversion from A to B

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  27. def lowPriorityTypeCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], ev: <:<[A, B]): CanEqual[A, B]

    Provides an A CanEqual B for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an implicit Equivalence[B].

    Provides an A CanEqual B for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an implicit Equivalence[B].

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits LowPriorityTypeCheckedConstraint (extended by TypeCheckedTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    equivalenceOfB

    an Equivalence[B] type class to which the Constraint.areEqual method will delegate to determine equality.

    ev

    evidence that A is a subype of B

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  28. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  29. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  30. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  31. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  32. def toString(): String
    Definition Classes
    AnyRef → Any
  33. def typeCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], ev: <:<[B, A]): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an implicit Equivalence[A].

    Provides an A CanEqual B instance for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an implicit Equivalence[A].

    The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s areEquivalent method to determine equality.

    This method is overridden and made implicit by subtraits TypeCheckedTripleEquals) and overriden as non-implicit by the other subtraits in this package.

    ev

    evidence that B is a subype of A

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  34. implicit def unconstrainedEquality[A, B](implicit equalityOfA: Equality[A]): CanEqual[A, B]

    Provides an A CanEqual B instance for any two types A and B, with no type constraint enforced, given an implicit Equality[A].

    Provides an A CanEqual B instance for any two types A and B, with no type constraint enforced, given an implicit Equality[A].

    The returned Constraint's areEqual method uses the implicitly passed Equality[A]'s areEqual method to determine equality.

    This method is overridden and made implicit by subtraits TripleEquals and overriden as non-implicit by the other subtraits in this package.

    equalityOfA

    an Equality[A] type class to which the Constraint.areEqual method will delegate to determine equality.

    returns

    an A CanEqual B instance whose areEqual method delegates to the areEqual method of the passed Equality[A].

    Definition Classes
    TripleEquals → TripleEqualsSupport
  35. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  36. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  37. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @native() @throws( ... )

Inherited from TripleEqualsSupport

Inherited from AnyRef

Inherited from Any

Ungrouped