use warnings;
use strict;
use B::Deparse;
use Data::Dump;


use constant DEBUG =>1;

BEGIN {
   unless (DEBUG) {
      *dmp = sub() {
         1;
      }
   } else {
      *dmp = sub($;@){
         shift;
         dd \@_;
      }
   }
}



sub test {
   #$_="#";
   my @a=1..3;
   dmp/#/,
     @a;
}

test();

warn "DEBUG = ",DEBUG,"\n";

print B::Deparse->new()->coderef2text(\&test);
[download]

OUTPUT

DEBUG = 0
{
    use warnings;
    use strict;
    my(@a) = 1..3;
    1 / @a;
}
[download]

Use of uninitialized value $_ in pattern match (m//) at ... line 27.
DEBUG = 1
[1, 2, 3]
{
    use warnings;
    use strict;
    my(@a) = 1..3;
    dmp /#/, @a;
}
[download]