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))
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))
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
.
the Spread[T]
against which to compare the left-hand value
a TripleEqualsInvocationOnSpread
wrapping the passed Spread[T]
value, with
expectingEqual
set to false
.
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
.
a null reference
a TripleEqualsInvocation
wrapping the passed null
value, with expectingEqual
set to false
.
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
.
the right-hand side value for an equality assertion
a TripleEqualsInvocation
wrapping the passed right value, with expectingEqual
set to false
.
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
.
the Spread[T]
against which to compare the left-hand value
a TripleEqualsInvocationOnSpread
wrapping the passed Spread[T]
value, with
expectingEqual
set to true
.
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
.
a null reference
a TripleEqualsInvocation
wrapping the passed null
value, with expectingEqual
set to true
.
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
.
the right-hand side value for an equality assertion
a TripleEqualsInvocation
wrapping the passed right value, with expectingEqual
set to true
.
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.
an Equivalence[A]
type class to which the Constraint.areEqual
method will delegate to determine equality.
an implicit conversion from B
to A
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed Equivalence[A]
.
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.
an Equivalence[B]
type class to which the Constraint.areEqual
method
will delegate to determine equality.
evidence that A
is a subype of B
an A CanEqual B
instance whose areEqual
method delegates to the
areEquivalent
method of the passed 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]
.
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.
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed Equivalence[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.
evidence that B
is a subype of A
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed 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]
.
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.
an Equivalence[A]
type class to which the Constraint.areEqual
method will delegate to determine equality.
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed Equivalence[A]
.
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.
the object whose type to convert to CheckingEqualizer
.
NullPointerException
if left
is null
.
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.
the object whose type to convert to Equalizer
.
NullPointerException
if left
is null
.
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 ==
.
a default Equality
for type A
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.
an implicit conversion from A
to B
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed 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]
.
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.
an Equivalence[B]
type class to which the Constraint.areEqual
method
will delegate to determine equality.
evidence that A
is a subype of B
an A CanEqual B
instance whose areEqual
method delegates to the
areEquivalent
method of the passed Equivalence[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.
evidence that B
is a subype of A
an A CanEqual B
instance whose areEqual
method delegates to the areEquivalent
method of
the passed Equivalence[A]
.
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.
an Equality[A]
type class to which the Constraint.areEqual
method will delegate to determine equality.
an A CanEqual B
instance whose areEqual
method delegates to the areEqual
method of
the passed Equality[A]
.
Provides
===
and!==
operators that returnBoolean
, delegate the equality determination to anEquality
type class, and require the types of the two values compared to be in a subtype/supertype relationship.TypeCheckedTripleEquals
is useful (in both production and test code) when you need a stricter type check than is provided by the SuperSafe Community Edition compiler plugin forTripleEquals
. For example, if you are developing a library that uses advanced features of Scala's type system, you may want to enforce in your tests that the types appearing in equality comparisons match exactly.By default under
TripleEquals
, any use of===
will compile, just like the==
operator:With SuperSafe Community Edition installed, the first two expressions above will be allowed to compile, but the third (which represents a likely bug) will not:
By contrast,
TypeCheckedTripleEquals
will prevent any of the above three expressions from compiling:Trait
TypeCheckedTripleEquals
rejects comparisons of typesInt
andLong
,List[Int]
andVector[Int]
, andString
andInt
, because none have a direct subtype/supertype relationship. To compare two types that are unrelated by inheritance underTypeCheckedTripleEquals
, you could convert one of them to the other type (because a type is both a subtype and supertype of itself). Here's an example:Nevertheless, a better (and the recommended) way to deal with this situation is to use a widening type ascription. A type ascription is simply a colon and a type placed next to a variable, usually surrounded by parentheses. For example, because
AnyVal
is a common supertype ofInt
andLong
, you could solve the type error by widening the type of one side or the other toAnyVal
. BecauseAnyVal
is a supertype of bothInt
andLong
, the type constraint will be satisfied:Similarly, since
Seq[Int]
is a common supertype of bothVector[Int]
andList[Int]
, the type constraint can be satisfied by widening either to their common supertype,Seq[Int]
:The primary intended use case for
TypeCheckedTripleEquals
is to enable tests to be very strict about which types can compared for equality, but it can also be used with production code where this level of strictness is desired.Forcing implicit conversions before equality checks
You can also use a type ascription to force an implicit conversion before a value participates in an equality comparison. For example, although
JavaConversions
provides an implicit conversion betweenjava.util.Set
andscala.collection.mutable.Set
, underTypeCheckedTripleEquals
an equality comparison between those two types will not be allowed:To force an implicit conversion of the Java
HashSet
to a Scalamutable.Set
, after which the type constraint will be satisfied, you can use a type ascription:Scoping equality policies
This trait will override or hide implicit methods defined by
TripleEquals
and can therefore be used to temporarily turn on or off type checking in a limited scope. Here's an example, in whichTypeCheckedTripleEquals
will cause a compiler error:Because
Int
andLong
are not in a subtype/supertype relationship, comparing1
and1L
in the context ofTypeCheckedTripleEquals
will generate a compiler error:You can “relax” the type checking locally by importing the members of
TripleEquals
in a limited scope:With the above change, the
Example.scala
file compiles fine. The strict checking is disabled only inside the firstcmp
method that takes anInt
and aLong
.TypeCheckedTripleEquals
is still enforcing its type constraint, for example, for thes === t
expression in the other overloadedcmp
method that takes strings.Because the methods
TripleEquals
andTypeCheckedTripleEquals
override all the methods defined in supertypeTripleEqualsSupport
, 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.