Re^4: How can I print variable contents from the debugger non-interactively? (@DB::typeahead)

[davehorner]

> 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.

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.

[LanX]

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.

[davehorner]

> I've shown you already 3 approaches, with varying details and footprint
I very much appreciate your responses!

> There is already a whole trace infrastructure apart from the debugger. the debugger IS eventually for interaction.
I've seen Devel::Trace but that also seems to only print the statements and not the data. If there is a whole trace infrastructure (/w data printing capabilities) outside of the debugger I am not aware of it and would appreciate a pointer if so.

[LanX]

Sorry I'm not really a user of debugger, tracer or profiler ....

... but you might want to have a look here

http://search.cpan.org/search?query=trace&mode=all

HTH! :)