[Israel.pm] Perl and Debugging question

[Gaal Yahas]

I disagree on both counts. :-)

Simplicity isn't one of the best descriptions of the debugger code.
(By which I mean
the actual debugger, perl5db.pl.) I mean sure, you could tweak around lines:
2434
654
5547

But you'd still have to bang your head against dumpvar.pl.

And how to make the interface for it? Just hardcode some arbitrary
limit? Yet another config option? What happens when your members are
actually tied scalars that when read do some expensive operation like
compute a value or read from the network? Maybe you want to skip those
fields too... How?

If what guides you is a sense that debuggability features don't seem
clean to leave in production code, I hear you, but consider that they
would be implemented in a separate unit of modularity (a Role, in the
case of Perl 6) and have declarative, thus uncluttering,
configuration. Incidentally, in Perl 6 Roles can be composed at
runtime, so your production program has absolutely no trace of this
filterable dumpage, until you drop into the debugger and add it to a
particular instance. Then you also have a consistent interface to mess
around with its properties.

On 5/14/07, Peter Gordon <peter at pg-consultants.com> wrote:
> It might be simpler and more consistent to add an option to the debugger
> itself.
>
> On Sun, 2007-05-13 at 21:50 +0300, Gaal Yahas wrote:
> > On 5/13/07, Peter Gordon <peter at pg-consultants.com> wrote:
> > > On this occasion, one of the elements is a string a few megabytes long,
> > > and I don't really want to dump the whole string.
> > >
> > > What would be the nicest way to suppress printing of this particular
> > > element.
> > >
> > > I could print each element in turn, but that is inelegant.
> >
> > I'm afraid I don't have an elegant solution to offer. (A related
> > problem that does
> > have debugger support is deeply recursive structures. Saying "x 3
> > $that" limits to
> > depth 3 print.)
> >
> > What you might do -- and I'm not saying this is significantly
> > different from printing each element in turn -- is add a to_debug
> > method to the object. This copies the object but only leaves a digest
> > version of the long string, say with the first 100 characters.
> >
> > Not that I've searched CPAN for prior art, but you might want to make
> > this into a reusable module. (With Moose.pm or Perl 6, it would more
> > properly be a Role.) Something like:
> >
> > package MyModuleWithLongMember;
> >
> > use Debug::Dump::Digest qw(long_memb1 huge_memb2);
> >
> > And then in the debugger:
> >
> > x $self->to_debug;
> >
>
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-- 
Gaal Yahas <gaal at forum2.org>
http://gaal.livejournal.com/