Packages

c

scala.reflect.macros

Attachments

abstract class Attachments extends AnyRef

EXPERIMENTAL

Attachments provide a way to associate custom metadata with symbols and trees.

Along with symbol and tpe, which represent core metadata of trees, each tree carries the attachments field that can store other metadata: compiler-defined (e.g. positions) or user-defined. Same story is true for symbols, which also have extensible metadata by the virtue of the same attachments field.

Typically attachments just store a scala.reflect.api.Position, but they can be extended to encompass arbitrary payloads. Payloads are stored in type-indexed slots, which can be read with get[T] and written with update[T] and remove[T].

This API doesn't have much use in the runtime reflection API (the scala.reflect.api package), but it might be of help for macro writers, providing a way to coordinate multiple macros operating on the same code. Therefore the attachments field is only declared in trees and symbols belonging to scala.reflect.macros.Universe.

Self Type
Attachments
Source
Attachments.scala
Linear Supertypes
AnyRef, Any
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  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
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  1. Public
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Instance Constructors

  1. new Attachments()

Type Members

  1. abstract type Pos >: Null

    The position type of this attachment

Abstract Value Members

  1. abstract def pos: Pos

    The underlying position

  2. abstract def withPos(newPos: Pos): Attachments { type Pos = Attachments.this.Pos }

    Creates a copy of this attachment with the position replaced by newPos

Concrete Value Members

  1. def all: Set[Any]

    The underlying payload with the guarantee that no two elements have the same type.

  2. def contains[T](implicit arg0: ClassTag[T]): Boolean

    Check underlying payload contains an instance of type T.

  3. def get[T](implicit arg0: ClassTag[T]): Option[T]

    An underlying payload of the given class type T.

  4. def isEmpty: Boolean
  5. def remove[T](implicit arg0: ClassTag[T]): Attachments { type Pos = Attachments.this.Pos }

    Creates a copy of this attachment with the payload of the given class type T removed.

  6. def update[T](attachment: T)(implicit arg0: ClassTag[T]): Attachments { type Pos = Attachments.this.Pos }

    Creates a copy of this attachment with the payload slot of T added/updated with the provided value.

    Creates a copy of this attachment with the payload slot of T added/updated with the provided value. Replaces an existing payload of the same type, if exists.