single_fiber_access.cr

struct SingleFiberAccess(T)
  @object : T
  {% if flag? :debug %}
    @fiber = Fiber.current
  {% end %}

  def initialize(@object)
  end

  macro method_missing(call)
    wrapped.{{ call.method }}({{ call.args }})
  end

  @[AlwaysInline]
  def wrapped
    {% if flag? :debug %}
      if @fiber != Fiber.current
        raise "wrong thread"
      end
    {% end %}
    @object
  end

  delegate to_s, inspect, to: wrapped
end

thing = SingleFiberAccess(Array(Int32)).new [1, 2, 3]

spawn do
  puts thing
end

Fiber.yield