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.
Attributes
- Companion
- object
- Source
- TripleEquals.scala
- Graph
-
- Supertypes
- Known subtypes
-
object TripleEquals.type
Members list
Type members
Inherited classlikes
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.
Attributes
- Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
- Supertypes
-
class Objecttrait Matchableclass Any
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.
Attributes
- Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
- Supertypes
-
class Objecttrait Matchableclass Any
Value members
Concrete methods
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.
Value parameters
- equivalenceOfB
-
an
Equivalence[B]
type class to which theConstraint.areEqual
method will delegate to determine equality. - ev
-
evidence that
A
is a subype of B
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[B]
. - Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality. - ev
-
evidence that
B
is a subype of A
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[A]
. - Definition Classes
- Source
- TripleEquals.scala
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
.
Attributes
- Throws
-
NullPointerException
if
left
isnull
. - Definition Classes
- Source
- TripleEquals.scala
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.
Value parameters
- equivalenceOfB
-
an
Equivalence[B]
type class to which theConstraint.areEqual
method will delegate to determine equality. - ev
-
evidence that
A
is a subype of B
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[B]
. - Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality. - ev
-
evidence that
B
is a subype of A
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[A]
. - Definition Classes
- Source
- TripleEquals.scala
Deprecated methods
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 theConstraint.areEqual
method will delegate to determine equality.
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[A]
. - Deprecated
- true
- Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality.
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[B]
. - Deprecated
- true
- Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality.
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[A]
. - Deprecated
- true
- Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality.
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEquivalent
method of the passedEquivalence[B]
. - Deprecated
- true
- Definition Classes
- Source
- TripleEquals.scala
Inherited methods
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
Attributes
- Returns
-
a
TripleEqualsInvocationOnSpread
wrapping the passedSpread[T]
value, withexpectingEqual
set tofalse
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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
Attributes
- Returns
-
a
TripleEqualsInvocation
wrapping the passednull
value, withexpectingEqual
set tofalse
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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
Attributes
- Returns
-
a
TripleEqualsInvocation
wrapping the passed right value, withexpectingEqual
set tofalse
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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
Attributes
- Returns
-
a
TripleEqualsInvocationOnSpread
wrapping the passedSpread[T]
value, withexpectingEqual
set totrue
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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
Attributes
- Returns
-
a
TripleEqualsInvocation
wrapping the passednull
value, withexpectingEqual
set totrue
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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
Attributes
- Returns
-
a
TripleEqualsInvocation
wrapping the passed right value, withexpectingEqual
set totrue
. - Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
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 ==
.
Attributes
- Returns
-
a default
Equality
for typeA
- Inherited from:
- TripleEqualsSupport
- Source
- TripleEqualsSupport.scala
Implicits
Implicits
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
.
Attributes
- Throws
-
NullPointerException
if
left
isnull
. - Definition Classes
- Source
- TripleEquals.scala
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 theConstraint.areEqual
method will delegate to determine equality.
Attributes
- Returns
-
an
A CanEqual B
instance whoseareEqual
method delegates to theareEqual
method of the passedEquality[A]
. - Definition Classes
- Source
- TripleEquals.scala