freezing procs

ractor_shenanigans.rb

# frozen_string_literal: true
# requires ruby 3.1+

# Ractor.make_shareable(proc) only succeeds if everything on the proc's binding is shareable.
#
# This makes it difficult to create wrappers around Ractor.new that accept an arbitrary block.
# Even this would still require the block declare any outer variables as block-locals, even if
# they aren't used.
class ProcFreezer
  def initialize = freeze
  def call(&); Ractor.current.instance_exec(&) => Proc => p; p end # block must return a Proc
  def make_shareable(&) = Ractor.make_shareable(call(&))
  def self.ractor(*a, name: nil, &b)
    f = new
    b = f.make_shareable(&b)
    i = f.make_shareable {->(a;name){ puts "inner? => %p" % [Ractor.current]; b.call(*a) }}
    r = Ractor.new(a, i, name: name) do |a, i|
      puts "init Ractor => %p" % Ractor.current
      i.call(a)
    end
  end
end

ProcFreezer
  .ractor do puts "make_shareable => %p" % [Ractor.current]; -> {:bar} end
  .take
# >> make_shareable => #<Ractor:#1 running>
# >> init Ractor => #<Ractor:#11 (irb):218 running>                                                                 
# >> inner? => #<Ractor:#11 (irb):218 running>                                                                      
# => :bar

honestly though, I'm probably better off just using fiddle to FFI-cheat with rb_isolate_proc_bang