iyi

Standard library, 0.18.0

std/box

Box allows turning any object to a Void* and back.

import std/box to use it. Source: src/std/box.iyi at v0.18.0.

A Box's purpose is passing data to C as a Void* and then converting that back to the original data type.

For example, sending Procs or context to C callbacks.

Box(T)class

std/boxiyi doc src/std/box.iyi
pub class Box(T)
  # Turns object into a Void*.
  #
  # Copies object to the heap inside a Box container if needed.
  def self.box(object : T) : ::Pointer(Void)
  def initialize(object : T)
  def object : T
  # Unboxes a Void* into an object of type T.
  #
  # Specifying T is required: `Box(T).unbox(data)`. A null pointer is nil
  # when T admits nil, as the other library answers it for `String?` and
  # every other union of references and nil, and is refused otherwise. It
  # was refused for every T, so `Box(String?).unbox` of the null a C
  # callback is handed when there is no data panicked "Unboxing null
  # pointer" where nil is the answer the type has room for.
  def self.unbox(pointer : ::Pointer(Void)) : T
end