Ruby Ractor: pass an arbitrary block

Sat, 21 Jan 2023 10:51:53 +0000

Let’s say you have a piece of code:

class SomeThing
  def initialize(thing)
    @thing = thing
  end

  def call
    puts @thing.inspect
  end
end

You want to execute this in parallel in a ractor:

Ractor.new { SomeThing.new(1).call }

This works if you have the block written within the Ractor. But it will fail if the block is refferenced from the outside of a ractor.

element = proc { SomeThing.new(1).call }
Ractor.new { element.call }

# <internal:ractor>:267:in `new': can not isolate a Proc because it accesses
#   outer variables (element). (ArgumentError)

To do that you need to instance_eval from a shareable object:

Ractor on Codrut Constantin Gusoi

Ruby Ractor: pass an arbitrary block