use warnings; use strict; three(5); sub three { return two(shift); } sub two { return one(_helper(shift)); } sub one { my $num = calc(shift); display($num); } sub calc { my $num = shift; return $num ** 3; } sub display { my $num = shift; print "$num\n"; } sub _helper { my $num = shift; return ++$num; } #### use warnings; use Devel::Trace::Subs qw(trace trace_dump); # injected by Devel::Trace::Subs use strict; three(5); sub three { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs return two(shift); } sub two { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs return one(_helper(shift)); } sub one { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs my $num = calc(shift); display($num); } sub calc { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs my $num = shift; return $num ** 3; } sub display { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs my $num = shift; print "$num\n"; } sub _helper { trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs my $num = shift; return ++$num; } #### $ENV{DTS_ENABLE} = 1; three(5); # this is the original call stack you're running trace_dump(); #### 216 Code flow: 1: main::three 2: main::two 3: main::_helper 4: main::one 5: main::calc 6: main::display Stack trace: in: main::three sub: - file: test.pl line: 7 package: main in: main::two sub: main::three file: test.pl line: 13 package: main in: main::_helper sub: main::two file: test.pl line: 17 package: main in: main::one sub: main::two file: test.pl line: 17 package: main in: main::calc sub: main::one file: test.pl line: 21 package: main in: main::display sub: main::one file: test.pl line: 22 package: main #### $ENV{DTS_ENABLE} = 1; trace_dump();