yes, it's still unclear for me if you want to step thru or run an automatic trace.

> Is there a way to provide this to the debugger via the $ENV{PERLDB_OPTS} variable?

Yes.

edit

At least in .perldb with afterinit

sub afterinit { push @DB::typeahead, "b 4", "b 6"; }

See perldebug#Debugger-Customization

you can also send debugger commands from inside the debugged Perl program ...

(though I don't recommend hard-coding linenumbers there, use $DB::single=1 to set a breakpoint in place)

use strict;
use warnings;

push @DB::typeahead,
  'b 19 $y==3',
  '{ X y'
  if exists &DB::DB;


$|=1;

my $a;
our $y;


for (0..10) {
   print;
   $a++;
   $y++;
}
[download]

runs as

  DB<22> c
0123auto(-3)  DB<22> X y
$y = 3
auto(-2)  DB<23> b 19 $y==3
auto(-1)  DB<24> { X y
  DB<25> c
45678910auto(-1)  DB<25> X y
  DB<26>
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}

> yes, it's still unclear for me if you want to step thru or run an automatic trace.

I think stepping thru the code would imply an interactive session. I am looking for an automatic trace, it would be nice to indicate which lines/variables should be printed, but having something that prints all of the variables modified and statements run would suffice. (huge output, but that isn't a problem!) There are some autotrace modules that may work, but I would like to accomplish this without additional modules. (lets make believe we are air gapped and getting to cpan is a problem)

> At least in .perldb with afterinit
sub afterinit { push @DB::typeahead, "b 4", "b 6"; }


So this isn't exactly thru the $ENV{PERLDB_OPTS} environment variable but using a file .perldb is easy enough to do. (though, @DB::typeahead is not a supported interface and is subject to change in future releases.)

I attempted the following:
echo "sub afterinit { push @DB::typeahead, \"a 119 p \$var\"; }" > .perldb

I see:


 29: main();
auto(-1) DB<1> a 199 p __DB<2> (some program output)
and then it shows 6556 segmentation fault  with exit code 139.
[download]

not sure what is causing the seg fault and I again lose the automatic printing of all the statements, but I see some of the program output. Hopefully the above typeahead gives you an idea of what I'm trying to accomplish.


Thanks again for all the thought and replies.

http://dave.thehorners.com/tech-talk/programming/94-perl-programming

There is already a whole trace infrastructure apart from the debugger.

Please note the debugger IS eventually for interaction.

And I've shown you already 3 approaches, with varying details and footprint

• print when you break back to prompt {
• print whenever you pass a certain point with a or b
• print whenever you execute any statement with w

> push @DB::typeahead, \"a 119 p \$var\";

Please note again that a , b and w only take real Perl code

but p is a debugger command

Commands accepting debugger commands are documented with db_cmd or db_command

  DB<27> h {
{ db_command    Define debugger command to run before each prompt.
{ ?            List debugger commands to run before each prompt.
{{ db_command    Add to the list of debugger commands to run before ea
+ch prompt.
{ *             Delete the list of debugger commands to run before eac
+h prompt.
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)
Je suis Charlie!}