How to set breakpoint on a particular file in Perl program?

Question

My Perl program looks like:

foo/ foo/bar/ for/bar/test.pm foo.pm foo/bar.pm test.pl 

and use perl test.pl to start the program. I want to debug a sub in foo/bar/test.pm. How to set a breakpoint on that sub?

How can I do this?

Thanks.

Answer 1

To debug a perl script, use the -d switch to invoke the debugger.

perl -d test.pl 

Within the debugger you can use b <line no> to set a breakpoint in the current file. Sometimes it is a hassle to set a breakpoint in a file that hasn't been loaded yet or that was loaded a long time ago, so you can also put the line

$DB::single = 1; 

anywhere in any perl program, and the debugger will break immediately after it executes that line. This is also a good way (the only way?) to set a breakpoint in code that will be run at compile time.