[gentoo-dev] perl question

[gentoo-dev] perl question

[Chad M. Huneycutt]

Can anyone explain to me why this I can't see $dir inside the unless 
block in the code fragment below?

sub recurse {
   my $dir = shift;

   print "dir: $dir\n";
   unless ( defined($exceptions{$dir}) ) {
      print "$dir is not an exception
   }
}

basically, dir is correct in the first print statement, and then gone 
inside the unless block (even if I do a "unless (0)", the second print 
shows $dir as undefined).

I basically want to make sure that the problem is not that I am unaware 
of some scoping rule of perl. I believe that this code is just acting 
unexpectedly, but I want to make sure before I spend any more time 
debugging it.  And yes, this is a gentoo-related program.

Thanks,
   Chad

Re: [gentoo-dev] perl question

[Terje Kvernes]

"Chad M. Huneycutt" <chad.huneycutt@acm.org> writes:

> Can anyone explain to me why this I can't see $dir inside the unless 
> block in the code fragment below?
> 
> sub recurse {
>    my $dir = shift;
> 
>    print "dir: $dir\n";
>    unless ( defined($exceptions{$dir}) ) {
>       print "$dir is not an exception
>    }
> }

  I expect you've left out a " on the second print statement? :)
 
> basically, dir is correct in the first print statement, and then
> gone inside the unless block (even if I do a "unless (0)", the
> second print shows $dir as undefined).

  it shouldn't. unless you've tied %exception into something that
  resets the keys on read. 
 
  $ perl -le '$foo="foo"; print $foo; unless( 0 ) { print $foo }'                                               
  foo
  foo

-- 
Terje

Re: [gentoo-dev] perl question

[Chad M. Huneycutt]

Terje Kvernes wrote:

>"Chad M. Huneycutt" <chad.huneycutt@acm.org> writes:
>
>>Can anyone explain to me why this I can't see $dir inside the unless 
>>block in the code fragment below?
>>
>>sub recurse {
>>   my $dir = shift;
>>
>>   print "dir: $dir\n";
>>   unless ( defined($exceptions{$dir}) ) {
>>      print "$dir is not an exception
>>   }
>>}
>>
>
>  I expect you've left out a " on the second print statement? :)
>

Yeah, this was a typo in the e-mail only.

>
> 
>
>>basically, dir is correct in the first print statement, and then
>>gone inside the unless block (even if I do a "unless (0)", the
>>second print shows $dir as undefined).
>>
>
>  it shouldn't. unless you've tied %exception into something that
>  resets the keys on read. 
>
I don't know why I was seeing this behavior, but I downloaded the 
program again, and the problem I was seeing here went away.

The actual problem was that the @#$@#%@# configuration file for my 
program (the file where $dir gets its value) was in MS-DOS format 
(newline and carriage return), which was causing some very strange 
behavior.  Kudos to kabau for helping me diagnose it!

Chad

Re: [gentoo-dev] perl question

[Terje Kvernes]

"Chad M. Huneycutt" <chad.huneycutt@acm.org> writes:

> Terje Kvernes wrote:
> 
> > I expect you've left out a " on the second print statement? :)
> 
> Yeah, this was a typo in the e-mail only.

  manual copy-paste. scary.
 
> > it shouldn't. unless you've tied %exception into something that
> > resets the keys on read.
> 
> I don't know why I was seeing this behavior, but I downloaded the
> program again, and the problem I was seeing here went away.

  interesting.
 
> The actual problem was that the @#$@#%@# configuration file for my
> program (the file where $dir gets its value) was in MS-DOS format
> (newline and carriage return), which was causing some very strange
> behavior. 

  you shouldn't notice this from perl. how are you parsing the
  configuration file?

> Kudos to kabau for helping me diagnose it!

  :)
 

-- 
Terje

Re: [gentoo-dev] perl question

[Chad M. Huneycutt]

Terje Kvernes wrote:

>>The actual problem was that the @#$@#%@# configuration file for my
>>program (the file where $dir gets its value) was in MS-DOS format
>>(newline and carriage return), which was causing some very strange
>>behavior. 
>>
>
>  you shouldn't notice this from perl. how are you parsing the
>  configuration file?
>
I did not write the application.  I am not sure why the carriage return 
at the end of the line was causing a problem as an argument to opendir, 
but the most irritating part was that when I printed out $dir, strange 
things could happen, which inhibited my debugging. :-)

Chad

P.S. if you want to see the code, it is a package called petrovich 
(hosted at sourceforge), and I will be checking it into app-misc 
sometime this weekend.

Re: [gentoo-dev] perl question

[Terje Kvernes]

"Chad M. Huneycutt" <chad.huneycutt@acm.org> writes:

> I did not write the application. I am not sure why the carriage
> return at the end of the line was causing a problem as an argument
> to opendir, but the most irritating part was that when I printed out
> $dir, strange things could happen, which inhibited my debugging. :-)

  hm. maybe opendir didn't like getting a ^M as a part of its
  argument. :)

  of course, printing it just might show it as "\n". that would be the
  cute part.

> P.S. if you want to see the code, it is a package called petrovich
> (hosted at sourceforge), and I will be checking it into app-misc
> sometime this weekend.

  I'll see if I'll bother. honestly, perl _should_ be transparent when
  it comes to newline habits. 

-- 
Terje - just another perl hacker.