dwickern / scala-nameof Edit

Get the name of an variable, function, class member, or type as a string--at compile-time!

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"nameOf" macro for scala

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Get the name of an variable, function, class member, or type as a string--at compile-time!

Inspired by the nameof operator in C#

Used to obtain the simple (unqualified) string name of a variable, type, or member. When reporting errors in code, hooking up model-view-controller (MVC) links, firing property changed events, etc., you often want to capture the string name of a method. Using nameof helps keep your code valid when renaming definitions. Before you had to use string literals to refer to definitions, which is brittle when renaming code elements because tools do not know to check these string literals.

Usage

Add the library as "provided", because it's only needed during compilation and not at runtime:

libraryDependencies += "com.github.dwickern" %% "scala-nameof" % "4.0.0" % "provided"

And import the package:

import com.github.dwickern.macros.NameOf._

Now you can use nameOf to get the name of a variable or class member:

case class Person(name: String, age: Int)

def toMap(person: Person) = Map(
  nameOf(person.name) -> person.name,
  nameOf(person.age) -> person.age
)
// compiles to:

def toMap(person: Person) = Map(
  "name" -> person.name,
  "age" -> person.age
)

To get the name of a function:

def startCalculation(value: Int): Unit = {
  println("Entered " + nameOf(startCalculation _))
}
// compiles to:

def startCalculation(value: Int): Unit = {
  println("Entered startCalculation")
}

Without having an instance of the type:

case class Person(name: String, age: Int) {
  def sayHello(other: Person) = s"Hello ${other.name}!"
}

println(nameOf[Person](_.age))
println(nameOf[Person](_.sayHello(???)))
// compiles to:

println("age")
println("sayHello")

You can also use nameOfType to get the unqualified name of a type:

println(nameOfType[java.lang.String])
// compiles to:

println("String")

And qualifiedNameOfType to get the qualified name:

println(qualifiedNameOfType[java.lang.String])
// compiles to:

println("java.lang.String")

Development

To run tests for all compilation targets:

sbt +test

To publish to your local ivy repository:

sbt +publishLocal

To publish to maven central (requires authorization):

sbt release

License

See LICENSE (MIT).