use strict;
use warnings;

use feature qw/say/;


=pod

Block sub is basically syntactic sugar for taking an anonymous sub {}
and returning it. Blessing it with "Block" facilitates syntax checks.

=cut

sub b(&) {
  my $c_block=shift;
  bless $c_block, "Block";
  return $c_block;
}

=pod

"yield" uses a little know trick to access the @_ of the caller.  It
checks the last argument of the caller, if its a ref blessed to
"Block" and calls it with the own arguments.

Note:
Ruby allows mixing normal arguments and blocks, as long as the
block is in the last position.  When using & prototypes in Perl like
in C<test(&&)> only the first block can be passed w/o leading sub.

=cut

sub yield {
  package DB;
  my ($package, $filename, $line, $subroutine)=caller(1);
  no warnings;
  my $c_block = $DB::args[-1];
  package main;
  return $c_block->(@_)
    if ref $c_block eq "Block";
  die "$subroutine called w/o block in $filename line $line";
}  

=pod

simulating the ruby test-code

=cut

sub test {
  say "You are in the method";
  yield 1;
  say "You are again back to the method";
  yield 2;
}


test b{ say "You are in the block $_[0]" };