Packages

  • package root
    Definition Classes
    root
  • package scala
    Definition Classes
    root
  • package reflect
    Definition Classes
    scala
  • package macros

    EXPERIMENTAL

    EXPERIMENTAL

    The base package for Scala macros.

    Macros are functions that are called by the compiler during compilation. Within these functions the programmer has access to compiler APIs. For example, it is possible to generate, analyze and typecheck code.

    See the Macros Guide on how to get started with Scala macros.

    Definition Classes
    reflect
  • package whitebox
    Definition Classes
    macros
  • trait Context extends blackbox.Context

    EXPERIMENTAL

    EXPERIMENTAL

    The whitebox Scala macros context.

    See the overview page for a description of how macros work. This documentation entry provides information on the API available to macro writers.

    A macro context wraps a compiler universe exposed in universe and having type scala.reflect.macros.Universe. This type is a refinement over the generic reflection API provided in scala.reflect.api.Universe. The extended Universe provides mutability for reflection artifacts (e.g. macros can change types of compiler trees, add annotation to symbols representing definitions, etc) and exposes some internal compiler functionality such as Symbol.deSkolemize or Tree.attachments.

    Another fundamental part of a macro context is macroApplication, which provides access to the tree undergoing macro expansion. Parts of this tree can be found in arguments of the corresponding macro implementations and in prefix, but macroApplication gives the full picture.

    Other than that, macro contexts provide facilities for typechecking, exploring the compiler's symbol table and enclosing trees and compilation units, evaluating trees, logging warnings/errors and much more. Refer to the documentation of top-level traits in this package to learn the details.

    If a macro def refers to a macro impl that uses whitebox.Context, then this macro def becomes a whitebox macro, gaining the ability to refine the type of its expansion beyond its official return type, which enables a number of important use cases. Blackbox macros, i.e. the ones defined with blackbox.Context, can't do that, so they are less powerful. However blackbox macros are also going to enjoy better support than whitebox macros, so choose wisely. See the Macros Guide for more information.

    Definition Classes
    whitebox
    See also

    scala.reflect.macros.blackbox.Context

  • ContextInternalApi
  • EnclosureException
  • ImplicitCandidate
  • PrefixType
  • TypecheckMode

case class ImplicitCandidate(pre: Context.Type, sym: Context.Symbol, pt: Context.Type, tree: Context.Tree) extends Product with Serializable

Information about one of the currently considered implicit candidates. Candidates are used in plural form, because implicit parameters may themselves have implicit parameters, hence implicit searches can recursively trigger other implicit searches.

pre and sym provide information about the candidate itself. pt and tree store the parameters of the implicit search the candidate is participating in.

Source
Context.scala
Linear Supertypes
Serializable, java.io.Serializable, Product, Equals, AnyRef, Any
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Inherited
  1. ImplicitCandidate
  2. Serializable
  3. Serializable
  4. Product
  5. Equals
  6. AnyRef
  7. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
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Visibility
  1. Public
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Instance Constructors

  1. new ImplicitCandidate(pre: Context.Type, sym: Context.Symbol, pt: Context.Type, tree: Context.Tree)

Value Members

  1. val pre: Context.Type
  2. val pt: Context.Type
  3. val sym: Context.Symbol
  4. val tree: Context.Tree