TripleEquals

Companion object TripleEquals

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 trait, 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;
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

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
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

final def !=(arg0: Any): Boolean
Definition Classes
AnyRef → Any
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
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
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
final def ##: Int
Definition Classes
AnyRef → Any
final def ==(arg0: Any): Boolean
Definition Classes
AnyRef → Any
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
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
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
final def asInstanceOf[T0]: T0
Definition Classes
Any
def clone(): AnyRef
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.CloneNotSupportedException]) @native()
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
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
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.
left
the object whose type to convert to CheckingEqualizer.
Definition Classes
TripleEquals → TripleEqualsSupport
Exceptions thrown
NullPointerException if left is null.
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.
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
final def eq(arg0: AnyRef): Boolean
Definition Classes
AnyRef
def equals(arg0: AnyRef): Boolean
Definition Classes
AnyRef → Any
def finalize(): Unit
Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.Throwable])
final def getClass(): Class[_ <: AnyRef]
Definition Classes
AnyRef → Any
Annotations
@native()
def hashCode(): Int
Definition Classes
AnyRef → Any
Annotations
@native()
final def isInstanceOf[T0]: Boolean
Definition Classes
Any
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
final def ne(arg0: AnyRef): Boolean
Definition Classes
AnyRef
final def notify(): Unit
Definition Classes
AnyRef
Annotations
@native()
final def notifyAll(): Unit
Definition Classes
AnyRef
Annotations
@native()
final def synchronized[T0](arg0: => T0): T0
Definition Classes
AnyRef
def toString(): String
Definition Classes
AnyRef → Any
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
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
final def wait(): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException])
final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
@throws(classOf[java.lang.InterruptedException]) @native()

Deprecated Value Members

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.
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
Annotations
@deprecated
Deprecated
(Since version 3.1.0) The conversionCheckedConstraint method has been deprecated and will be removed in a future version of ScalaTest. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.
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.
returns
an A CanEqual B instance whose areEqual method delegates to the areEquivalent method of the passed Equivalence[B].
Definition Classes
TripleEquals → TripleEqualsSupport
Annotations
@deprecated
Deprecated
(Since version 3.1.0) The convertEquivalenceToAToBConversionConstraint method has been deprecated and will be removed in a future version of ScalaTest. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.
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.
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
Annotations
@deprecated
Deprecated
(Since version 3.1.0) The convertEquivalenceToBToAConversionConstraint method has been deprecated and will be removed in a future version of ScalaTest. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.
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.
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
Annotations
@deprecated
Deprecated
(Since version 3.1.0) The lowPriorityConversionCheckedConstraint method has been deprecated and will be removed in a future version of ScalaTest. It is no longer needed now that the deprecation period of ConversionCheckedTripleEquals has expired. It will not be replaced.

Packages

TripleEquals

Companion object TripleEquals

trait TripleEquals extends TripleEqualsSupport

Type Members

Value Members

Deprecated Value Members

Inherited from TripleEqualsSupport

Inherited from AnyRef

Inherited from Any

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Packages

TripleEquals

Companion object TripleEquals

trait TripleEquals extends TripleEqualsSupport

Type Members

Value Members

Deprecated Value Members

Inherited from TripleEqualsSupport

Inherited from AnyRef

Inherited from Any

Ungrouped

TripleEquals