Update: Didn't realize that Ruby's 'yield' did not involve 'real' coroutines. The OP has since been updated.

Here's my take on accomplishing "sort of" the same thing in a couple of different ways (w/regard to argument passing) w/Coro. I know it's not the same thing, but worth comparing and contrasting and thinking about:

use Coro::State;
use Coro::Channel;

{

my $new;
my $test = sub {
  my ($m, $f) = @_;
  print "In method\n";
  $f->(1);
  $new->transfer($m);
  print "In method again\n";
  $f->(2);
  $new->cancel();
  $new->transfer($m);
};

my $main = Coro::State->new();
my $f = sub { print "In block: $_[0]\n" };
$new = Coro::State->new($test, $main, $f);

while ( !$new->is_zombie() ) {
  $main->transfer($new);
}

print "Done!\n";

}

{

my $new;
my $test = sub {
  my ($m, $q) = @_;
  print "In method\n";
  $q->put(1);
  $new->transfer($m);
  print "In method again\n";
  $q->put(2);
  $new->cancel();
  $new->transfer($m);
};

my $main = Coro::State->new();
my $ch = Coro::Channel->new();
$new = Coro::State->new($test, $main, $ch);

while ( !$new->is_zombie() ) {
  $main->transfer($new);
  my $got = $ch->get();
  print "Inblock: $got\n";
}

print "Done!\n";
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