[Mastering-perl] Debugging chapter comments

[Derek B. Smith]

--- brian d foy <brian.d.foy at gmail.com> wrote:

> I've been busy lately. I think I've finished the
> first pass on two
> more chapters. Let me know if I left out any major
> topics I should
> have discussed. I'd especially like everyone to look
> at these chapters
> and ask themselves "Would my co-worker learn
> everything I want him to
> know about this subject by reading this chapter?" If
> your answer is
> "No", let me know what else you want!
> 
> I've added a bunch of stuff to the Debugging
> chapter:

Hi Brian, 

In YoUr DeBuGgiNg CHapTEr, (oops sorry about the case
mix...still thinking I am on myspace :) under "Doing
whatever I want" you mention modifying the %SIG hash
which is good but I think you fail to clearly state
the benefits of this.  For example I use this code in
my header template as a centralized die routine
instead of having a bunch of dies with prints:

my $overide = $SIG{__DIE__};   ## get error handler
currently assigned 2 die
$SIG{__DIE__} = sub {
 my $error = shift;      ## error now holds the mesg
passed to die
 $overide->($error) if ( ref $overide );
 print LOG ($error);
};

It looks like croak is a more informed version of DIE
so I will make the switch. thank you.

UNder Program tracing you state: Each subroutine call
put a frame with all of its information onto the
stack[4]. 

It should read Each subroutine call can place a frame
with all of its information onto the stack[4]. 

Please define frame here!?

In your final block of code explaining debugging do
you intend this code to be a substitute for a
centralized die/croak routine?  Or do you intend this
to serve as routine that will give the most detail
that can be used in any situation b/c I notice you are
checking if its a reference?  I guess I was
overwhelmed, but impressed so maybe "put it all
together" in a final example.

BEGIN {
use Carp::Heavy;

no warnings 'redefine';
*Carp::format_arg = sub {
    package Carp;
    my $arg = shift;

    if( not defined $arg ) 
        { $arg = 'undef' }
    elsif( ref $arg ) 
...
...
   $arg =~
s/([[:cntrl:]]|[[:^ascii:]])/sprintf("\\x{%x}",ord($1))/eg;
    return $arg;
    };
}

Finally, 

I use Eclipse IDE and I love it.  It offers spell
checker, an integrated debugger with the padwalker
module that runs perl5db under the covers and nicely
displays all the information one needs to debug. 
Maybe pick your top 3 and go more in depth.  My top 3
would be Esclipe, Komodo and perl5db command line.

thank you
derek

derek



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