org.scalactic

LowPriorityConversionCheckedConstraint

trait LowPriorityConversionCheckedConstraint extends TripleEqualsSupport

Provides an implicit conversion that will be applied only if a higher-priority implicit conversion declared a subtrait is not applicable.

The purpose of this trait is to make the === operator symetric. In other words, a === invocation will be allowed if an implicit conversion exists in either direction. For example, the implicit widening conversion from Int to Long will be applied on the left hand side in this expression:

1 === 1L

But in the next expression, it will be applied on the right hand side:

1L === 1

The first expression above is enabled by the implicit conversion conversionCheckedConstraint in traits ConversionCheckedTripleEquals and ConversionCheckedLegacyTripleEquals. The second expression above is enabled by the implicit conversion lowPriorityConversionCheckedConstraint in this trait.

The reason these two implicit methods aren't both declared in the subtraits is that if implicit conversions were available in both directions, they would conflict. By placing one of them in this supertrait, the higher priority conversion will be selected.

Source
LowPriorityConversionCheckedConstraint.scala
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TripleEqualsSupport, AnyRef, Any
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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
  3. class LegacyCheckingEqualizer[L] extends AnyRef

    Class used via an implicit conversion to enable any two objects to be compared with === and !== with an Option[String] result and an enforced type constraint between two object types.

    Class used via an implicit conversion to enable any two objects to be compared with === and !== with an Option[String] 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))
    

    The benefit of using assert(a === b) rather than assert(a == b) in ScalaTest code is that a TestFailedException produced by the former will include the values of a and b in its detail message.

    Note: This class has "Legacy" in its name because its approach to error messages will eventually be replaced by macros. Once ScalaTest no longer supports Scala 2.9, this class will be deprecated in favor of class Equalizer. Instead of obtaining nice error messages via the Option[String] returned by the methods of this class, the error messages will be obtained by a macro. The "legacy" approach to good error messages will continue to be used, however, until ScalaTest no longer supports Scala 2.9, since macros were introduced to Scala (in experimental form) in 2.10.

    The primary constructor takes one object, left, whose type is being converted to Equalizer. The left value may be a null reference, because this is allowed by Scala's == operator.

    Definition Classes
    TripleEqualsSupport
  4. class LegacyEqualizer[L] extends AnyRef

    Class used via an implicit conversion to enable any two objects to be compared with === and !== with an Option[String] 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 an Option[String] 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))
    

    The benefit of using assert(a === b) rather than assert(a == b) in ScalaTest code is that a TestFailedException produced by the former will include the values of a and b in its detail message.

    Note: This class has "Legacy" in its name because its approach to error messages will eventually be replaced by macros. Once ScalaTest no longer supports Scala 2.9, this class will be deprecated in favor of class Equalizer. Instead of obtaining nice error messages via the Option[String] returned by the methods of this class, the error messages will be obtained by a macro. The "legacy" approach to good error messages will continue to be used, however, until ScalaTest no longer supports Scala 2.9, since macros were introduced to Scala (in experimental form) in 2.10.

    The primary constructor takes one object, left, whose type is being converted to Equalizer. The left value may be a null reference, because this is allowed by Scala's == operator.

    Definition Classes
    TripleEqualsSupport

Abstract Value Members

  1. abstract def conversionCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], cnv: (B) ⇒ A): Constraint[A, B]

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

    Provides a Constraint[A, B] class 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 ConversionCheckedLegacyTripleEquals, 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

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEqualsSupport
  2. abstract def convertEquivalenceToAToBConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: <:<[A, B]): Constraint[A, B]

    Provides a Constraint[A, 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 Constraint[A, 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 LowPriorityTypeCheckedLegacyConstraint (extended by TypeCheckedLegacyTripleEquals), 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

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEqualsSupport
  3. abstract def convertEquivalenceToBToAConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: <:<[B, A]): Constraint[A, B]

    Provides a Constraint[A, B] 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 a Constraint[A, B] 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 TypeCheckedLegacyTripleEquals, and overriden as non-implicit by the other subtraits in this package.

    ev

    evidence that B is a subype of A

    returns

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEqualsSupport
  4. abstract def convertEquivalenceToBToAConversionConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: (B) ⇒ A): Constraint[A, B]

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

    Provides a Constraint[A, B] class 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 ConversionCheckedLegacyTripleEquals, 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

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEqualsSupport
  5. abstract 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
    TripleEqualsSupport
    Exceptions thrown
    NullPointerException

    if left is null.

  6. abstract 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
    TripleEqualsSupport
    Exceptions thrown
    NullPointerException

    if left is null.

  7. abstract def convertToLegacyCheckingEqualizer[T](left: T): LegacyCheckingEqualizer[T]

    Converts to a LegacyCheckingEqualizer that provides === and !== operators that result in Option[String] and enforce a type constraint.

    Converts to a LegacyCheckingEqualizer that provides === and !== operators that result in Option[String] and enforce a type constraint.

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

    left

    the object whose type to convert to LegacyCheckingEqualizer.

    Definition Classes
    TripleEqualsSupport
    Exceptions thrown
    NullPointerException

    if left is null.

  8. abstract def convertToLegacyEqualizer[T](left: T): LegacyEqualizer[T]

    Converts to a LegacyEqualizer that provides === and !== operators that result in Option[String] and enforce no type constraint.

    Converts to a LegacyEqualizer that provides === and !== operators that result in Option[String] and enforce no type constraint.

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

    left

    the object whose type to convert to LegacyEqualizer.

    Definition Classes
    TripleEqualsSupport
    Exceptions thrown
    NullPointerException

    if left is null.

  9. abstract def lowPriorityTypeCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], ev: <:<[A, B]): Constraint[A, B]

    Provides a Constraint[A, 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 a Constraint[A, 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 LowPriorityTypeCheckedLegacyConstraint (extended by TypeCheckedLegacyTripleEquals), 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

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    TripleEqualsSupport
  10. abstract def typeCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], ev: <:<[B, A]): Constraint[A, B]

    Provides a Constraint[A, B] 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 a Constraint[A, B] 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 TypeCheckedLegacyTripleEquals, and overriden as non-implicit by the other subtraits in this package.

    ev

    evidence that B is a subype of A

    returns

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[A].

    Definition Classes
    TripleEqualsSupport
  11. abstract def unconstrainedEquality[A, B](implicit equalityOfA: Equality[A]): Constraint[A, B]

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

    Provides a Constraint[A, B] class 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 LegacyTripleEquals, 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

    a Constraint[A, B] whose areEqual method delegates to the areEqual method of the passed Equality[A].

    Definition Classes
    TripleEqualsSupport

Concrete 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
    @throws( ... )
  12. implicit def convertEquivalenceToAToBConversionConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: (A) ⇒ B): Constraint[A, B]

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

    Provides a Constraint[A, B] class 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 LowPriorityConversionCheckedLegacyConstraint (extended by ConversionCheckedLegacyTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    returns

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    LowPriorityConversionCheckedConstraintTripleEqualsSupport
  13. 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
  14. final def eq(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  15. def equals(arg0: Any): Boolean

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

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

    Definition Classes
    AnyRef → Any
  18. def hashCode(): Int

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

    Definition Classes
    Any
  20. implicit def lowPriorityConversionCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], cnv: (A) ⇒ B): Constraint[A, B]

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

    Provides a Constraint[A, B] class 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 LowPriorityConversionCheckedLegacyConstraint (extended by ConversionCheckedLegacyTripleEquals), and overriden as non-implicit by the other subtraits in this package.

    cnv

    an implicit conversion from A to B

    returns

    a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].

    Definition Classes
    LowPriorityConversionCheckedConstraintTripleEqualsSupport
  21. final def ne(arg0: AnyRef): Boolean

    Definition Classes
    AnyRef
  22. final def notify(): Unit

    Definition Classes
    AnyRef
  23. final def notifyAll(): Unit

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

    Definition Classes
    AnyRef
  25. def toString(): String

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

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

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

    Definition Classes
    AnyRef
    Annotations
    @throws( ... )

Inherited from TripleEqualsSupport

Inherited from AnyRef

Inherited from Any

Ungrouped