Scalactic 3.2.17/org.scalactic/LowPriorityTypeCheckedConstraint

LowPriorityTypeCheckedConstraint

trait LowPriorityTypeCheckedConstraint 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 subtype relationship exists in either direction. For example, in the following expression, the left hand side is a subtype of the right hand side:

List(1, 2, 3) === Seq(1, 2, 3)

But in the next expression, it the right hand side is a subtype of the left hand side

Seq(1, 2, 3) === List(1, 2, 3)

The first expression above is enabled by the implicit conversion typeCheckedConstraint in trait TypeCheckedTripleEquals. The second expression above is enabled by the implicit conversion lowPriorityTypeCheckedConstraint in this trait.

The reason these two implicit methods aren't both declared in the subtraits is that if the subtype relationship existed in both directions, they would conflict. This can happen when the exact same type is on both the left and right hand sides, because a type is a subtype of itself. By placing one of them in this supertrait, the higher priority conversion will be selected.

Source:
LowPriorityTypeCheckedConstraint.scala
class Object
trait Matchable
class Any

Type members

Inherited classlikes

class CheckingEqualizer[L](val leftSide: L)

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:

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))
Value parameters:
leftSide

An object to convert to Equalizer, which represents the value on the left side of a === or !== invocation.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
class Equalizer[L](val leftSide: L)

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:

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))
Value parameters:
leftSide

An object to convert to Equalizer, which represents the value on the left side of a === or !== invocation.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala

Value members

Inherited methods

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.

Value parameters:
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.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
right

a null reference

Returns:

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

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
right

the right-hand side value for an equality assertion

Returns:

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

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
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.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
right

a null reference

Returns:

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

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
right

the right-hand side value for an equality assertion

Returns:

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

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
equalityOfA

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

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].

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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 subtrait TypeCheckedTripleEquals, and overriden as non-implicit by the other subtraits in this package.

Value parameters:
left

the object whose type to convert to CheckingEqualizer.

Throws:
NullPointerException

if left is null.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
left

the object whose type to convert to Equalizer.

Throws:
NullPointerException

if left is null.

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
equalityOfA

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

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].

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
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.

Value parameters:
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].

Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala

Deprecated and Inherited methods

@deprecated("The conversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.", "3.1.0")
def conversionCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], cnv: B => A): CanEqual[A, B]

The conversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

The conversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

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.

Value parameters:
cnv

an implicit conversion from B to A

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].

Deprecated
Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
@deprecated("The convertEquivalenceToAToBConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.", "3.1.0")
def convertEquivalenceToAToBConversionConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: A => B): CanEqual[A, B]

The convertEquivalenceToAToBConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

The convertEquivalenceToAToBConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

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.

Value parameters:
cnv

an implicit conversion from A to B

equalityOfB

an Equivalence[B] 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[B].

Deprecated
Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
@deprecated("The convertEquivalenceToBToAConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.", "3.1.0")
def convertEquivalenceToBToAConversionConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: B => A): CanEqual[A, B]

The convertEquivalenceToBToAConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

The convertEquivalenceToBToAConversionConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

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.

Value parameters:
cnv

an implicit conversion from B to A

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].

Deprecated
Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala
@deprecated("The lowPriorityConversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.", "3.1.0")
def lowPriorityConversionCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], cnv: A => B): CanEqual[A, B]

The lowPriorityConversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

The lowPriorityConversionCheckedConstraint method has been deprecated and will be removed in a future version of Scalactic. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

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.

Value parameters:
cnv

an implicit conversion from A to B

equalityOfB

an Equivalence[B] 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[B].

Deprecated
Inherited from:
TripleEqualsSupport
Source:
TripleEqualsSupport.scala

Implicits

Implicits

implicit override def convertEquivalenceToAToBConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: A <:< B): CanEqual[A, B]
implicit override def lowPriorityTypeCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], ev: A <:< B): CanEqual[A, B]