LazyArg

Transforms a given object's toString with a given function lazily.

This class is intended to be used with the mapResult method of MatcherProducers, which you can use to modify error messages when composing matchers. This class exists to enable those error messages to be modified lazily, so that toString is invoked on the given arg, and its result transformed by the given function f, only when and if the toString method is invoked on the LazyArg. As a performance optimization, ScalaTest's MatchResult avoids invoking toString on objects until and unless an error message is actually needed, to minimize unecessary creation and concatenation of strings. The LazyArg class enables this same performance optimization when composing matchers.

The other design goal of LazyArg is to make the internal arg available for inspection in an IDE. In a future version of ScalaTest, the args of MatchResult that were used to create the error message will be included in the TestFailedException, so they can be inspected in IDEs. This is why the arg field of LazyArg is public.

For an example of using LazyArg, see the Composing matchers section in the main documentation for trait Matcher.

arg: the argument
f: a function that given the arg will produce a String

Source: LazyArg.scala

Linear Supertypes

Serializable, Serializable, Product, Equals, AnyRef, Any

Instance Constructors

new LazyArg(arg: Any)(f: (Any) ⇒ String)

arg
the argument
f
a function that given the arg will produce a String

Value Members

final def !=(arg0: Any): Boolean

Definition Classes
AnyRef → Any
final def ##(): Int

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

Definition Classes
AnyRef → Any
val arg: Any

the argument
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 finalize(): Unit

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

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

Returns the result of invoking the function f, passed to the LazyArg constructor, on field arg.
Returns the result of invoking the function f, passed to the LazyArg constructor, on field arg.

Definition Classes
LazyArg → 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( ... )

Related Doc: package matchers

final case class LazyArg(arg: Any)(f: (Any) ⇒ String) extends Product with Serializable

Instance Constructors

new LazyArg(arg: Any)(f: (Any) ⇒ String)

Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: Any): Boolean

val arg: Any

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def finalize(): Unit

final def getClass(): Class[_]

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 Serializable

Inherited from Serializable

Inherited from Product

Inherited from Equals

Inherited from AnyRef

Inherited from Any

Ungrouped