Length

Supertrait for Length typeclasses.

Trait Length is a typeclass trait for objects that can be queried for length. Objects of type T for which an implicit Length[T] is available can be used with the should have length syntax. In other words, this trait enables you to use the length checking syntax with arbitrary objects. As an example, the following Bridge class:

scala> import org.scalatest._
import org.scalatest._

scala> import enablers.Length
import enablers.Length

scala> import Matchers._
import Matchers._

scala> case class Bridge(span: Int)
defined class Bridge

Out of the box you can't use the should have length syntax with Bridge, because ScalaTest doesn't know that a bridge's span means its length:

scala> val bridge = new Bridge(2000)
bridge: Bridge = Bridge(2000)

scala> bridge should have length 2000
<console>:34: error: could not find implicit value for
    parameter len: org.scalatest.enablers.Length[Bridge]
      bridge should have length 2000
                         ^

You can teach this to ScalaTest, however, by defining an implicit Length[Bridge].

scala> implicit val lengthOfBridge: Length[Bridge] =
     |   new Length[Bridge] {
     |     def lengthOf(b: Bridge): Long = b.span
     |   }
lengthOfBridge: org.scalatest.enablers.Length[Bridge] = $anon$1@3fa27a4a

With the implicit Length[Bridge] in scope, you can now use ScalaTest's should have length syntax with Bridge instances:

scala> bridge should have length 2000
res4: org.scalatest.Assertion = Succeeded

scala> bridge should have length 2001
org.scalatest.exceptions.TestFailedException: Bridge(2000) had length 2000 instead of expected length 2001
  at org.scalatest.MatchersHelper$.newTestFailedException(MatchersHelper.scala:148)
  at org.scalatest.MatchersHelper$.indicateFailure(MatchersHelper.scala:366)
  at org.scalatest.Matchers$ResultOfHaveWordForExtent.length(Matchers.scala:2720)
  ... 43 elided

Source: Length.scala

Linear Supertypes

AnyRef, Any

Abstract Value Members

abstract def lengthOf(obj: T): Long

Returns the length of the passed object.
Returns the length of the passed object.
obj
the object whose length to return
returns
the length of the passed object

Concrete Value Members

final def !=(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def !=(arg0: Any): Boolean

Definition Classes
Any
final def ##(): Int

Definition Classes
AnyRef → Any
final def ==(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def ==(arg0: Any): Boolean

Definition Classes
Any
final def asInstanceOf[T0]: T0

Definition Classes
Any
def clone(): AnyRef

Attributes
protected[java.lang]
Definition Classes
AnyRef
Annotations
@throws( ... )
final def eq(arg0: AnyRef): Boolean

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

Definition Classes
AnyRef → Any
def finalize(): Unit

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

Definition Classes
AnyRef → Any
def hashCode(): Int

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

Definition Classes
Any
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

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

Definition Classes
AnyRef
def toString(): String

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

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

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

Definition Classes
AnyRef
Annotations
@throws( ... )

trait Length[T] extends AnyRef

Abstract Value Members

abstract def lengthOf(obj: T): Long

Concrete Value Members

final def !=(arg0: AnyRef): Boolean

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: AnyRef): Boolean

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

Inherited from AnyRef

Inherited from Any

Ungrouped