ValueEnum

Base trait for val-based enums, i.e. enums implemented as a single class with companion object keeping enum values as instances of the enum class in final val fields. This is an alternative way of implementing enums as compared to traditional Scala approach of using a sealed hierarchy with objects representing enum values.

Advantages of value based enums over object based enums include:

Much less classes generated, which in particular contributes to much less JavaScript output in ScalaJS. This may also speed up compilation.
No need to explicitly implement values in enum's companion object as it is necessary when using SealedEnumCompanion and NamedEnumCompanion
It is possible to define all enum values in a single line of code (assuming they don't take parameters)

Disadvantages of value based enums over object based enums include:

Every object can have its own separate public API, values cannot (although you can have a separate anonymous class for every value)
Scala compiler does not perform exhaustive checking for pattern matching enum values - this is however provided separately by commons-analyzer compiler plugin.

Enum classes must have a companion object which extends ValueEnumCompanion (prefer using AbstractValueEnumCompanion where possible). Every enum constant must be declared as a final val in the companion object and must have the Value type explicitly ascribed. The enum class itself must take an implicit EnumCtx argument which provides information about enum ordinal and name as well as makes sure that enum value is registered in the companion object. If possible, you should always extend AbstractValueEnum instead of mixing in this trait. ValueEnum trait should only be mixed in directly when your enum class already has another superclass, incompatible with AbstractValueEnum.

Example:

final class Weekday(implicit enumCtx: EnumCtx) extends AbstractValueEnum
object Weekday extends AbstractValueEnumCompanion[Weekday] {
  final val Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday: Value = new Weekday
}

Value based enums can take parameters:

final class Status(val description: String)(implicit enumCtx: EnumCtx) extends AbstractValueEnum
object Status extends AbstractValueEnumCompanion[Status] {
  final val Enabled: Value = new Status("Something is enabled and working")
  final val Disabled: Value = new Status("Something is disabled and not working")
}

Linear Supertypes

NamedEnum, Serializable, Serializable, AnyRef, Any

Known Subclasses

AbstractValueEnum

Abstract Value Members

abstract def enumCtx: EnumCtx

Attributes
protected

Concrete 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
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
def name: String

Name of the final val in enum companion object that this enum value is assigned to.
Name of the final val in enum companion object that this enum value is assigned to.

Definition Classes
ValueEnum → NamedEnum
final def ne(arg0: AnyRef): Boolean

Definition Classes
AnyRef
final def notify(): Unit

Definition Classes
AnyRef
final def notifyAll(): Unit

Definition Classes
AnyRef
def ordinal: Int

Enum value index, starting from 0.
Enum value index, starting from 0. Reflects the order in which enum constants are declared in the companion object of the enum class.
final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
def toString(): String

Definition Classes
NamedEnum → 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 Docs: object ValueEnum | package misc

trait ValueEnum extends NamedEnum

Abstract Value Members

abstract def enumCtx: EnumCtx

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

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

def name: String

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

def ordinal: Int

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 NamedEnum

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

Ungrouped