in reply to Debugging a module?

Put $DB::single = 1; just before the first line you want to stop at in the module. I rarely use breakpoints with the perl debugger anymore, since that trick works just as well in BEGIN blocks as in regular code, and it works well as a conditional breakpoint too:

$DB::single = 1 if $name eq 'mark';

which I prefer for no apparent reason to

$DB::single = ($name eq 'mark');

Alternatively, you could put BEGIN { $DB::single = 1; } just before you use the module, but there's a good chance you'll end up stepping through a bunch of other modules you don't care about that way.

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Re^2: Debugging a module?
by dstar (Scribe) on Apr 06, 2006 at 13:49 UTC
    If I do the $DB::single = 1 with a use statement, it breaks on the last line of the module -- which is '1;'. With a require statement, I get the results I mentioned easily. I haven't tried wrapping it in a BEGIN statement -- that's a good idea.
[reply]
      Either your perl behaves very differently from mine, or I didn't describe it very well. If I use these two files:

      driver.pl 

      use TestModule;

print "I am exiting now.\n";

      [download]

      TestModule.pm 

      package TestModule;

our $x = 0;
$DB::single = 1;
our $y = $x + 1;
our $z = $y ** 3;

sub blah { "blah!" }

1;

      [download]

      ...and run perl -d driver.pl, the debugger immediately stops at the line our $y = $x + 1. Do you get different results?

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