Factory

A factory to create new instances, especially dynamic mix-ins.

Author:

Source

Examples:

Given a trait that has abstract members.

trait Foo {
  val bar: Int
  var baz: Long
}

When creating a factory for the trait.

val factory = Factory[Foo]

Then the newInstance method of the factory should accept named arguments according to abstract members.

val createdFromNamedArguments: Foo = factory.newInstance(bar = 1, baz = 2L)
createdFromNamedArguments.bar should be(1)
createdFromNamedArguments.baz should be(2L)

When using unnamed parameters, the parameters should be passed in alphabetical order

val createdFromUnnamedArguments: Foo = factory.newInstance(1, 2L)
createdFromUnnamedArguments.bar should be(1)
createdFromUnnamedArguments.baz should be(2L)

Given two traits that have no abstract member.
```
trait Foo
trait Bar
```
When creating a factory for mix-in type of the two types.
```
val factory = Factory[Foo with Bar]
```
Then the newInstance method of the factory should accept no parameters.
```
val fooBar: Foo with Bar = factory.newInstance()
fooBar should be(a[Foo])
fooBar should be(a[Bar])
```
Given a trait that contains an abstract method annotated as @inject.
```
import com.thoughtworks.feature.Factory.inject
trait Foo[A] {
  @inject def orderingA: Ordering[A]
}
```
When creating a factory for the trait
```
val factory = Factory[Foo[Int]]
```
Then the @inject method will be replaced to an implicit value.
```
val foo = factory.newInstance()
foo.orderingA should be(implicitly[Ordering[Int]])
```
It will not compile if no implicit value found. For example, Foo[Symbol] requires an implicit value of type Ordering[Symbol], which is not availble.
```
"Factory[Foo[Symbol]]" shouldNot compile
```
If the trait does not contain abstract methods other than @inject methods, then the factory type class is a Factory.Nullary, which can be summoned by Predef.implicitly,
```
val nullaryFactory = implicitly[Factory.Nullary[Foo[Int]]]
```
and newInstance method is available on the Factory.Nullary as well.
```
nullaryFactory.newInstance().orderingA should be(implicitly[Ordering[Int]])
```

Note

However, if the nested type is an alias to another type outside of the type to create, then it is allowed

trait Outer {
  type Inner = String
  val inner: Option[Inner]
}
val outer: Outer = Factory[Outer].newInstance(inner = Some("my value"))
outer.inner should be(Some("my value"))

This Factory disallows creating types that has an abstract member whose type depends on nested types

trait Outer {
  trait Inner
  val inner: Option[Inner]
}
"Factory.newInstance[Outer](inner = None)" shouldNot typeCheck

@inject works on implicit abstract methods as well.

import com.thoughtworks.feature.Factory.inject
trait Foo[A] {
  @inject implicit def orderingA: Ordering[A]
}
Factory[Foo[Int]].newInstance().orderingA should be(implicitly[Ordering[Int]])

Factories may be nested

import com.thoughtworks.feature.Factory.inject
trait Outer {
  trait AbstractParameterApi
  type AbstractParameter <: AbstractParameterApi
  trait InnerApi {
    def foo: AbstractParameter
  }
  type Inner <: InnerApi
  @inject val innerFactory: Factory.UnaryByName[AbstractParameter, Inner]
}
Factory[Outer]

Linear Supertypes

Serializable, Serializable, AnyRef, Any

Type Hierarchy

Type Members

abstract type Constructor

A function type that returns Output.
A function type that returns Output.
The parameter types are all abstract members in Output

Abstract Value Members

abstract val newInstance: Constructor

Returns an instance of Output, which overrides abstract members in Output according to parameters pass to this newInstance method.

Concrete Value Members

final def !=(arg0: Any): Boolean

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

Definition Classes
AnyRef → Any
def +(other: String): String

Implicit information
This member is added by an implicit conversion from Factory[Output] to any2stringadd[Factory[Output]] performed by method any2stringadd in scala.Predef.
Definition Classes
any2stringadd
def ->[B](y: B): (Factory[Output], B)

Implicit information
This member is added by an implicit conversion from Factory[Output] to ArrowAssoc[Factory[Output]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
@inline()
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( ... )
def ensuring(cond: (Factory[Output]) ⇒ Boolean, msg: ⇒ Any): Factory[Output]

Implicit information
This member is added by an implicit conversion from Factory[Output] to Ensuring[Factory[Output]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: (Factory[Output]) ⇒ Boolean): Factory[Output]

Implicit information
This member is added by an implicit conversion from Factory[Output] to Ensuring[Factory[Output]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean, msg: ⇒ Any): Factory[Output]

Implicit information
This member is added by an implicit conversion from Factory[Output] to Ensuring[Factory[Output]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
def ensuring(cond: Boolean): Factory[Output]

Implicit information
This member is added by an implicit conversion from Factory[Output] to Ensuring[Factory[Output]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
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] )
def formatted(fmtstr: String): String

Implicit information
This member is added by an implicit conversion from Factory[Output] to StringFormat[Factory[Output]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
@inline()
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( ... )
def →[B](y: B): (Factory[Output], B)

Implicit information
This member is added by an implicit conversion from Factory[Output] to ArrowAssoc[Factory[Output]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc

Related Docs: object Factory | package feature

trait Factory[Output] extends Serializable

Author:

Type Members

abstract type Constructor

Abstract Value Members

abstract val newInstance: Constructor

Concrete Value Members

final def !=(arg0: Any): Boolean

final def ##(): Int

def +(other: String): String

def ->[B](y: B): (Factory[Output], B)

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

def ensuring(cond: (Factory[Output]) ⇒ Boolean, msg: ⇒ Any): Factory[Output]

def ensuring(cond: (Factory[Output]) ⇒ Boolean): Factory[Output]

def ensuring(cond: Boolean, msg: ⇒ Any): Factory[Output]

def ensuring(cond: Boolean): Factory[Output]

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

def formatted(fmtstr: String): String

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

def →[B](y: B): (Factory[Output], B)

Inherited from Serializable

Inherited from Serializable

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from Factory[Output] to any2stringadd[Factory[Output]]

Inherited by implicit conversion StringFormat from Factory[Output] to StringFormat[Factory[Output]]

Inherited by implicit conversion Ensuring from Factory[Output] to Ensuring[Factory[Output]]

Inherited by implicit conversion ArrowAssoc from Factory[Output] to ArrowAssoc[Factory[Output]]

Ungrouped