pointerof

The pointerof expression returns a Pointer that points to the contents of a variable or instance variable.

An example with a variable:

  1. a = 1
  3. ptr = pointerof(a)
  4. ptr.value = 2
  6. a #=> 2

An example with an instance variable:

  1. class Point
  2.   def initialize(@x : Int32, @y : Int32)
  3.   end
  5.   def x
  6.     @x
  7.   end
  9.   def x_ptr
  10.     pointerof(@x)
  11.   end
  12. end
  14. point = Point.new 1, 2
  16. ptr = point.x_ptr
  17. ptr.value = 10
  19. point.x #=> 10

Because pointerof involves pointers, it is considered unsafe.