[28270] in Perl-Users-Digest
Perl-Users Digest, Issue: 9634 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Aug 22 06:06:17 2006
Date: Tue, 22 Aug 2006 03:05:05 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 22 Aug 2006 Volume: 10 Number: 9634
Today's topics:
Re: constructing a scalar reference <josef.moellers@fujitsu-siemens.com>
Re: constructing a scalar reference (Heinrich Mislik)
Re: constructing a scalar reference anno4000@radom.zrz.tu-berlin.de
Re: constructing a scalar reference <mumia.w.18.spam+nospam.usenet@earthlink.net>
Re: constructing a scalar reference anno4000@radom.zrz.tu-berlin.de
extracst the first 8 bits with pack <betterdie@gmail.com>
Re: extracst the first 8 bits with pack anno4000@radom.zrz.tu-berlin.de
Re: HOW to rename a NPH script ? <umu@hrz.tu-chemnitz.de>
Re: ioctl TIOCSCTTY errno -1 <vivekm1234@cyberspace.org>
Re: ioctl TIOCSCTTY errno -1 <vivekm1234@cyberspace.org>
new CPAN modules on Tue Aug 22 2006 (Randal Schwartz)
OO Perl - How to maintain class state when using inheri jeff_nokes@yahoo.com
Re: OO Perl - How to maintain class state when using in <mumia.w.18.spam+nospam.usenet@earthlink.net>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Question about UNIVERSAL <bol@adv.magwien.gv.at>
Re: Use of uninitialized value in string eq at ./xml_si <Brett.R.Davis@gmail.com>
Re: Use of uninitialized value in string eq at ./xml_si <Brett.R.Davis@gmail.com>
Re: Use of uninitialized value in string eq at ./xml_si <Brett.R.Davis@gmail.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 22 Aug 2006 08:37:13 +0200
From: Josef Moellers <josef.moellers@fujitsu-siemens.com>
Subject: Re: constructing a scalar reference
Message-Id: <ece8pp$un2$1@nntp.fujitsu-siemens.com>
Dibosia wrote:
> $r =3D {}; # a hashref
> $r =3D []; # an arrayref
These are _anonymous_ references (i.e. the thingy referred to (the=20
"referent"?) has no name of its own).
> $r =3D ?; # a scalar ref
AFAIK no _anonymous_ scalar references exist.
--=20
Josef M=F6llers (Pinguinpfleger bei FSC)
If failure had no penalty success would not be a prize
-- T. Pratchett
------------------------------
Date: 22 Aug 2006 08:44:48 GMT
From: Heinrich.Mislik@univie.ac.at (Heinrich Mislik)
Subject: Re: constructing a scalar reference
Message-Id: <44eac400$0$12384$3b214f66@usenet.univie.ac.at>
In article <1156193008.889984.212180@75g2000cwc.googlegroups.com>, skunktrunk@gmail.com says...
>
>
>$r = {}; # a hashref
>$r = []; # an arrayref
>$r = ?; # a scalar ref
>
>What is ? ? I want to pass a ref to a scalar (pass by reference)
>without resorting to
Anything wrong with
$r = \undef;
Cheers
Heinrich
--
Heinrich Mislik
Zentraler Informatikdienst der Universitaet Wien
A-1010 Wien, Universitaetsstrasse 7
Tel.: (+43 1) 4277-14056, Fax: (+43 1) 4277-9140
------------------------------
Date: 22 Aug 2006 08:48:06 GMT
From: anno4000@radom.zrz.tu-berlin.de
Subject: Re: constructing a scalar reference
Message-Id: <4kvum5Fbo9f0U1@news.dfncis.de>
Heinrich Mislik <Heinrich.Mislik@univie.ac.at> wrote in comp.lang.perl.misc:
> In article <1156193008.889984.212180@75g2000cwc.googlegroups.com>,
> skunktrunk@gmail.com says...
> >
> >
> >$r = {}; # a hashref
> >$r = []; # an arrayref
> >$r = ?; # a scalar ref
> >
> >What is ? ? I want to pass a ref to a scalar (pass by reference)
> >without resorting to
>
> Anything wrong with
>
> $r = \undef;
Yes, it's read-only. You won't be able to say "$$r = 123" later. For
that matter, you can't even bless it.
Anno
------------------------------
Date: Tue, 22 Aug 2006 08:57:09 GMT
From: "Mumia W." <mumia.w.18.spam+nospam.usenet@earthlink.net>
Subject: Re: constructing a scalar reference
Message-Id: <FFzGg.92$bM.78@newsread4.news.pas.earthlink.net>
On 08/21/2006 03:43 PM, Dibosia wrote:
> $r = {}; # a hashref
> $r = []; # an arrayref
> $r = ?; # a scalar ref
>
> What is ? ? [...]
$r = \"This is a string.";
------------------------------
Date: 22 Aug 2006 09:28:10 GMT
From: anno4000@radom.zrz.tu-berlin.de
Subject: Re: constructing a scalar reference
Message-Id: <4l011aFe62mhU2@news.dfncis.de>
Mumia W. <mumia.w.18.spam+nospam.usenet@earthlink.net> wrote in comp.lang.perl.misc:
> On 08/21/2006 03:43 PM, Dibosia wrote:
> > $r = {}; # a hashref
> > $r = []; # an arrayref
> > $r = ?; # a scalar ref
> >
> > What is ? ? [...]
>
> $r = \"This is a string.";
Like Heinrich Mislik's "\ undef" approach that results in a reference
to a read-only value. You can't assign to it and you can't bless it.
That makes it rather useless for most purposes.
Anno
------------------------------
Date: 22 Aug 2006 01:08:27 -0700
From: "perlistpaul" <betterdie@gmail.com>
Subject: extracst the first 8 bits with pack
Message-Id: <1156234107.858521.196940@74g2000cwt.googlegroups.com>
Hello everyone,
my purpose of the code is to do the following, put number into array,
and extracts the first 8bits from each stored number, interprets there
8bits chunks as characters.
Isn't it correct?
--------------------------------------
for(@bitplay)
{
$count++;
print pack("A6x5A1x1A1x3 s","Number","#",$count,$_),"\n";
}
my $str=pack("lll",@bitplay);
print "String is ". $str."\n";
----------------
Thank you
paul
------------------------------
Date: 22 Aug 2006 09:24:42 GMT
From: anno4000@radom.zrz.tu-berlin.de
Subject: Re: extracst the first 8 bits with pack
Message-Id: <4l00qqFe62mhU1@news.dfncis.de>
perlistpaul <betterdie@gmail.com> wrote in comp.lang.perl.misc:
> Hello everyone,
>
> my purpose of the code is to do the following, put number into array,
There is only one array, @bitplay, in your code. Nothing puts a
number in there, your code assumes it is already set. That is
unfortunate because we don't know what you assume it is set to.
> and extracts the first 8bits from each stored number, interprets there
> 8bits chunks as characters.
By the "first" eight bits you presumably mean the lowest-numbered byte
in the four byte sequence that make up the number. You are aware that
the content of that byte will depend on the architecture (little/big
endian) the program runs on.
> Isn't it correct?
Is what correct? Your code shows two different ways of extracting
things from @bitplay and prints them. Both show no relationship
to what you described above.
> --------------------------------------
> for(@bitplay)
> {
> $count++;
> print pack("A6x5A1x1A1x3 s","Number","#",$count,$_),"\n";
>
> }
>
> my $str=pack("lll",@bitplay);
>
> print "String is ". $str."\n";
This may get you started:
my $n = 0x61626364; # "abcd"
my $first_byte = substr pack( 'l', $n), 0, 1;
print "$first_byte\n"; # "d" on little endian, "a" on big endian
Anno
------------------------------
Date: Tue, 22 Aug 2006 07:41:13 +0200
From: Ulrich Mueller <umu@hrz.tu-chemnitz.de>
Subject: Re: HOW to rename a NPH script ?
Message-Id: <Pine.LNX.4.64.0608220716290.21794@herein.hrz.tu-chemnitz.de>
On Mon, 21 Aug 2006, anno4000@radom.zrz.tu-berlin.de wrote:
> What's to consider about 3? The fact that you got no replies elsewhere
> doesn't make it topical here. When the baker is closed, do you go to the
> butcher next door to get your breakfast rolls?
>
> Anno
>
yes, I wanted a sandwich with bacon,
and usually get it from either the baker or the butcher,
as long as there's no war...
------------------------------
Date: Tue, 22 Aug 2006 09:44:13 +0530
From: Vivek.M <vivekm1234@cyberspace.org>
Subject: Re: ioctl TIOCSCTTY errno -1
Message-Id: <s4vke2hkftppamjp9qaculcm4dcg4cmnfj@4ax.com>
> On 21 Aug 2006 20:24:38 GMT, xhoster@gmail.com wrote:
>The first thing I'd do to debug it would either be strace -f the perl, or
>to re-write your example code into the analogous C code, which shouldn't be
>too hard, and see what happens there.
Yup, you were right :( :) I did it in C and i get Input/Output error.
Error no 5 in errno.h. So what do i do now? What the heck is a IO
error on /dev/tty imply? I've googled and can't seem to figure it out!
#include <signal.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
int main(void) {
pid_t pid;
int fd;
fd = open("/dev/tty",O_RDWR, 0);
if(fd == -1)
fprintf(stderr,"can't acquire terminal");
if( (pid = fork() ) < 0) {
fprintf(stderr, "Unable to fork process \n");
}
if(pid == 0) {
sleep(5);
if(setsid() < 0)
fprintf(stderr, "setsid error \n");
if( (ioctl(fd, TIOCSCTTY, NULL)) < 0)
printf("Error number: %d\n", errno);
}
return 0;
------------------------------
Date: Tue, 22 Aug 2006 11:47:09 +0530
From: Vivek.M <vivekm1234@cyberspace.org>
Subject: Re: ioctl TIOCSCTTY errno -1
Message-Id: <248le2l19fbd5q8ee9s7jp6l34mffjs036@4ax.com>
> On Tue, 22 Aug 2006 09:44:13 +0530, Vivek.M <vivekm1234@cyberspace.org> wrote:
Okay figured it out but am not any closer to getting this to work :).
when i call setsid i create a new session with the child being session
leader of this new session unfortunately it looses it's old
controlling terminal association which is why ioctl bombs. The old
session still exists and still retains control over /dev/tty *sigh*
So what i need to do is kill off the old session and then call ioctl.
------------------------------
Date: Tue, 22 Aug 2006 04:42:08 GMT
From: merlyn@stonehenge.com (Randal Schwartz)
Subject: new CPAN modules on Tue Aug 22 2006
Message-Id: <J4DuE8.uCo@zorch.sf-bay.org>
The following modules have recently been added to or updated in the
Comprehensive Perl Archive Network (CPAN). You can install them using the
instructions in the 'perlmodinstall' page included with your Perl
distribution.
Acme-Note-0.1
http://search.cpan.org/~ferreira/Acme-Note-0.1/
Make a mental note for programming style
----
Apache-DBI-1.03
http://search.cpan.org/~pgollucci/Apache-DBI-1.03/
Initiate a persistent database connection
----
Apache-Session-Generate-UUID-0.1
http://search.cpan.org/~sock/Apache-Session-Generate-UUID-0.1/
UUID for session ID generation
----
App-SimpleScan-1.19
http://search.cpan.org/~mcmahon/App-SimpleScan-1.19/
simple_scan's core code
----
CGI-Wiki-Store-Mediawiki-0.01
http://search.cpan.org/~dprice/CGI-Wiki-Store-Mediawiki-0.01/
Mediawiki (MySQL) storage backend for CGI::Wiki
----
CGI.pm-3.21
http://search.cpan.org/~lds/CGI.pm-3.21/
----
Class-Std-Slots-v0.0.3
http://search.cpan.org/~andya/Class-Std-Slots-v0.0.3/
Provide signals and slots for standard classes.
----
Config-LotusNotes-0.21
http://search.cpan.org/~albers/Config-LotusNotes-0.21/
Access Lotus Notes configuration
----
DBIx-Romani-0.0.14
http://search.cpan.org/~dsnopek/DBIx-Romani-0.0.14/
----
Data-FormValidator-4.40
http://search.cpan.org/~markstos/Data-FormValidator-4.40/
Validates user input (usually from an HTML form) based on input profile.
----
DateTime-TimeZone-0.47
http://search.cpan.org/~drolsky/DateTime-TimeZone-0.47/
Time zone object base class and factory
----
Genezzo-0.64
http://search.cpan.org/~jcohen/Genezzo-0.64/
an extensible database with SQL and DBI
----
HTTP-Async-0.01
http://search.cpan.org/~evdb/HTTP-Async-0.01/
process multiple HTTP requests in parallel without blocking.
----
LWPx-ParanoidAgent-1.03
http://search.cpan.org/~bradfitz/LWPx-ParanoidAgent-1.03/
subclass of LWP::UserAgent that protects you from harm
----
MDV-Distribconf-3.00
http://search.cpan.org/~nanardon/MDV-Distribconf-3.00/
Read and write config of a Mandriva Linux distribution tree
----
MDV-Distribconf-3.01
http://search.cpan.org/~nanardon/MDV-Distribconf-3.01/
Read and write config of a Mandriva Linux distribution tree
----
MDV-Distribconf-3.02
http://search.cpan.org/~nanardon/MDV-Distribconf-3.02/
Read and write config of a Mandriva Linux distribution tree
----
Mail-SpamCannibal-0.70
http://search.cpan.org/~miker/Mail-SpamCannibal-0.70/
A tool to stop SPAM
----
Net-Flickr-API-1.4
http://search.cpan.org/~ascope/Net-Flickr-API-1.4/
base API class for Net::Flickr::* libraries
----
Net-Flickr-Backup-2.9
http://search.cpan.org/~ascope/Net-Flickr-Backup-2.9/
OOP for backing up your Flickr photos locally
----
Net-Flickr-RDF-1.9
http://search.cpan.org/~ascope/Net-Flickr-RDF-1.9/
a.k.a RDF::Describes::Flickr
----
Net-SFTP-Foreign-0.90_12
http://search.cpan.org/~salva/Net-SFTP-Foreign-0.90_12/
Secure File Transfer Protocol client
----
Net-Whois-Raw-1.13
http://search.cpan.org/~despair/Net-Whois-Raw-1.13/
Get Whois information for domains
----
POE-Component-AI-MegaHAL-1.01
http://search.cpan.org/~bingos/POE-Component-AI-MegaHAL-1.01/
A non-blocking wrapper around AI::MegaHAL.
----
POE-Component-Win32-ChangeNotify-1.01
http://search.cpan.org/~bingos/POE-Component-Win32-ChangeNotify-1.01/
A POE wrapper around Win32::ChangeNotify.
----
POE-Component-Win32-EventLog-1.05
http://search.cpan.org/~bingos/POE-Component-Win32-EventLog-1.05/
A POE component that provides non-blocking access to Win32::EventLog.
----
POE-Component-Win32-Service-1.02
http://search.cpan.org/~bingos/POE-Component-Win32-Service-1.02/
A POE component that provides non-blocking access to Win32::Service.
----
PPM-Make-0.79
http://search.cpan.org/~rkobes/PPM-Make-0.79/
Make a ppm package from a CPAN distribution
----
Pugs-Compiler-Rule-0.16
http://search.cpan.org/~fglock/Pugs-Compiler-Rule-0.16/
Compiler for Perl 6 Rules
----
Text-Smart-1.0.1
http://search.cpan.org/~danberr/Text-Smart-1.0.1/
Processor for 'smart text' markup
----
Text-Smart-Plugin-1.0.1
http://search.cpan.org/~danberr/Text-Smart-Plugin-1.0.1/
Template Toolkit plugin for Text::Smart
----
Time-HiRes-1.88
http://search.cpan.org/~jhi/Time-HiRes-1.88/
High resolution alarm, sleep, gettimeofday, interval timers
----
Time-Piece-Adaptive-0.01
http://search.cpan.org/~dprice/Time-Piece-Adaptive-0.01/
subclass of Time::Piece which allows the default stringification function to be set.
----
Xmldoom-0.0.14
http://search.cpan.org/~dsnopek/Xmldoom-0.0.14/
The XML Document Object-Oriented Model
----
v6-alpha-0.014
http://search.cpan.org/~fglock/v6-alpha-0.014/
If you're an author of one of these modules, please submit a detailed
announcement to comp.lang.perl.announce, and we'll pass it along.
This message was generated by a Perl program described in my Linux
Magazine column, which can be found on-line (along with more than
200 other freely available past column articles) at
http://www.stonehenge.com/merlyn/LinuxMag/col82.html
print "Just another Perl hacker," # the original
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@stonehenge.com> <URL:http://www.stonehenge.com/merlyn/>
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!
------------------------------
Date: 22 Aug 2006 00:53:08 -0700
From: jeff_nokes@yahoo.com
Subject: OO Perl - How to maintain class state when using inherited methods?
Message-Id: <1156233188.677194.22430@h48g2000cwc.googlegroups.com>
Hi,
Here are a couple example class files:
#Collection.pm
package Collection;
our $ClassType = 'Collection_type'; # Class variable
sub new ($;) {
my($class_name) = @_;
my $self = {};
$self->{class_name} = __PACKAGE__;
$self->{property_1} = 'foo';
bless($self, $class_name);
return($self);
}# end new()
sub serializeObject($;) {
my($self) = @_;
my $serialized_object = $ClassType . ',' .
$self->{class_name} . ',' .
$self->{property_1};
return($serialized_object);
}# end serializeObject()
sub getClassType($;) {
return($ClassType);
}# end getClassType()
1;
----------------------------------
#Addresses.pm
package Addresses;
use Collection;
our @ISA = (
'Collection',
);
our $ClassType = 'Addresses_type'; # Class variable.
1;
-------------------------------
Test script:
perl -e 'use Data::Dumper; use Collection; use Addresses;'\
-e 'my $obj_addr = Addresses->new();'\
-e 'print("\n" . Dumper($obj_addr) . "\n" . '\
-e ' "Serialized Object = " . $obj_addr->serializeObject() .
"\n" . '\
-e ' "getClassTtype = " . $obj_addr->getClassType() . "\n"'\
-e ');'
--------------------------------
Output:
$VAR1 = bless( {
'class_name' => 'Collection',
'property_1' => 'foo'
}, 'Addresses' );
Serialized Object = Collection_type,Collection,foo
getClassTtype = Collection_type
---------------------------------------
Questions:
(1) Referencing the dumped object in the above output, I can see that
the namespace of the object is 'Addresses', but all of the internal
properties are that of the parent class Collection.pm. Is it that the
namespace was set to 'Addresses' simply due to the arrow notation
implicitly invoking the parent class' new() method? And the object
really has Collection properties because Perl already walked up the ISA
tree into the Collection namespace?
(2) Both classes have the same class level variable $ClassType. Even
though the namespace of the $obj_addr is 'Addresses', when invoking the
inherited method getClassType(), the output still reflects that of the
parent class' $ClassType? Why? Again, has Perl already walked up the
ISA tree to execute this inherited method, and therefore it sees the
namespace 'Collection' vice 'Addresses'?
(3) If I want to keep Addresses level stateful data inside the object,
is the proper way to do so to pass the data into the inherited
constuctor as arguments?
example:
$obj_addr = Addresses->new($Addresses::ClassType);
Collection.pm: new()
------------
sub new ($;$) {
my($class_name, $stateful_data) = @_;
my $self = {};
$self->{data_type} = $stateful_data;
bless($self, $class_name);
return($self);
}# end new()
I feel like I'm missing some basic premis, that this should be able to
be done without the explicit need to pass the data into the inherited
constructor. Does anyone have any suggestions on how to achieve this
differenlty then my example above?
Thanks in advance for any advice you can offer.
- J.
------------------------------
Date: Tue, 22 Aug 2006 09:27:28 GMT
From: "Mumia W." <mumia.w.18.spam+nospam.usenet@earthlink.net>
Subject: Re: OO Perl - How to maintain class state when using inherited methods?
Message-Id: <46AGg.7231$Sn3.1044@newsread3.news.pas.earthlink.net>
On 08/22/2006 02:53 AM, jeff_nokes@yahoo.com wrote:
> Hi,
> Here are a couple example class files:
>
> #Collection.pm
>
> package Collection;
>
> our $ClassType = 'Collection_type'; # Class variable
>
> sub new ($;) {
> my($class_name) = @_;
> my $self = {};
> $self->{class_name} = __PACKAGE__;
> $self->{property_1} = 'foo';
> bless($self, $class_name);
> return($self);
> }# end new()
>
>
> sub serializeObject($;) {
> my($self) = @_;
> my $serialized_object = $ClassType . ',' .
> $self->{class_name} . ',' .
> $self->{property_1};
> return($serialized_object);
> }# end serializeObject()
>
>
> sub getClassType($;) {
> return($ClassType);
> }# end getClassType()
>
> 1;
>
> ----------------------------------
>
> #Addresses.pm
>
> package Addresses;
>
> use Collection;
>
> our @ISA = (
> 'Collection',
> );
>
> our $ClassType = 'Addresses_type'; # Class variable.
>
> 1;
>
> -------------------------------
>
> Test script:
>
> perl -e 'use Data::Dumper; use Collection; use Addresses;'\
> -e 'my $obj_addr = Addresses->new();'\
> -e 'print("\n" . Dumper($obj_addr) . "\n" . '\
> -e ' "Serialized Object = " . $obj_addr->serializeObject() .
> "\n" . '\
> -e ' "getClassTtype = " . $obj_addr->getClassType() . "\n"'\
> -e ');'
>
> --------------------------------
>
> Output:
>
> $VAR1 = bless( {
> 'class_name' => 'Collection',
> 'property_1' => 'foo'
> }, 'Addresses' );
>
> Serialized Object = Collection_type,Collection,foo
> getClassTtype = Collection_type
>
> ---------------------------------------
>
> Questions:
>
> (1) Referencing the dumped object in the above output, I can see that
> the namespace of the object is 'Addresses', but all of the internal
> properties are that of the parent class Collection.pm. Is it that the
> namespace was set to 'Addresses' simply due to the arrow notation
> implicitly invoking the parent class' new() method? And the object
> really has Collection properties because Perl already walked up the ISA
> tree into the Collection namespace?
>
Yes
> (2) Both classes have the same class level variable $ClassType. Even
> though the namespace of the $obj_addr is 'Addresses', when invoking the
> inherited method getClassType(), the output still reflects that of the
> parent class' $ClassType? Why? Again, has Perl already walked up the
> ISA tree to execute this inherited method, and therefore it sees the
> namespace 'Collection' vice 'Addresses'?
>
Yes
> (3) If I want to keep Addresses level stateful data inside the object,
> is the proper way to do so to pass the data into the inherited
> constuctor as arguments?
>
No
> example:
>
> $obj_addr = Addresses->new($Addresses::ClassType);
>
> Collection.pm: new()
> ------------
> sub new ($;$) {
> my($class_name, $stateful_data) = @_;
> my $self = {};
> $self->{data_type} = $stateful_data;
This is better:
$self->{data_type} = __PACKAGE__;
> bless($self, $class_name);
> return($self);
> }# end new()
>
>
> I feel like I'm missing some basic premis, that this should be able to
> be done without the explicit need to pass the data into the inherited
> constructor. Does anyone have any suggestions on how to achieve this
> differenlty then my example above?
>
> Thanks in advance for any advice you can offer.
>
> - J.
>
Read "perldoc perltooc" and possibly use Class::Data::Inheritable.
------------------------------
Date: 22 Aug 2006 07:22:03 GMT
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.6 $)
Message-Id: <44eab09a$0$47258$ae4e5890@news.nationwide.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.6 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
intended to be used for discussion of Perl related issues (except job
postings), whether it be comments or questions.
As you would expect, clpmisc discussions are usually very technical in
nature and there are conventions for conduct in technical newsgroups
going somewhat beyond those in non-technical newsgroups.
The article at:
http://www.catb.org/~esr/faqs/smart-questions.html
describes how to get answers from technical people in general.
This article describes things that you should, and should not, do to
increase your chances of getting an answer to your Perl question. It is
available in POD, HTML and plain text formats at:
http://www.augustmail.com/~tadmc/clpmisc.shtml
For more information about netiquette in general, see the "Netiquette
Guidelines" at:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
A note to newsgroup "regulars":
Do not use these guidelines as a "license to flame" or other
meanness. It is possible that a poster is unaware of things
discussed here. Give them the benefit of the doubt, and just
help them learn how to post, rather than assume
A note about technical terms used here:
In this document, we use words like "must" and "should" as
they're used in technical conversation (such as you will
encounter in this newsgroup). When we say that you *must* do
something, we mean that if you don't do that something, then
it's unlikely that you will benefit much from this group.
We're not bossing you around; we're making the point without
lots of words.
Do *NOT* send email to the maintainer of these guidelines. It will be
discarded unread. The guidelines belong to the newsgroup so all
discussion should appear in the newsgroup. I am just the secretary that
writes down the consensus of the group.
Before posting to comp.lang.perl.misc
Must
This section describes things that you *must* do before posting to
clpmisc, in order to maximize your chances of getting meaningful replies
to your inquiry and to avoid getting flamed for being lazy and trying to
have others do your work.
The perl distribution includes documentation that is copied to your hard
drive when you install perl. Also installed is a program for looking
things up in that (and other) documentation named 'perldoc'.
You should either find out where the docs got installed on your system,
or use perldoc to find them for you. Type "perldoc perldoc" to learn how
to use perldoc itself. Type "perldoc perl" to start reading Perl's
standard documentation.
Check the Perl Frequently Asked Questions (FAQ)
Checking the FAQ before posting is required in Big 8 newsgroups in
general, there is nothing clpmisc-specific about this requirement.
You are expected to do this in nearly all newsgroups.
You can use the "-q" switch with perldoc to do a word search of the
questions in the Perl FAQs.
Check the other standard Perl docs (*.pod)
The perl distribution comes with much more documentation than is
available for most other newsgroups, so in clpmisc you should also
see if you can find an answer in the other (non-FAQ) standard docs
before posting.
It is *not* required, or even expected, that you actually *read* all of
Perl's standard docs, only that you spend a few minutes searching them
before posting.
Try doing a word-search in the standard docs for some words/phrases
taken from your problem statement or from your very carefully worded
"Subject:" header.
Really Really Should
This section describes things that you *really should* do before posting
to clpmisc.
Lurk for a while before posting
This is very important and expected in all newsgroups. Lurking means
to monitor a newsgroup for a period to become familiar with local
customs. Each newsgroup has specific customs and rituals. Knowing
these before you participate will help avoid embarrassing social
situations. Consider yourself to be a foreigner at first!
Search a Usenet archive
There are tens of thousands of Perl programmers. It is very likely
that your question has already been asked (and answered). See if you
can find where it has already been answered.
One such searchable archive is:
http://groups.google.com/advanced_group_search
If You Like
This section describes things that you *can* do before posting to
clpmisc.
Check Other Resources
You may want to check in books or on web sites to see if you can
find the answer to your question.
But you need to consider the source of such information: there are a
lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.cpan.org/authors/id/D/DM/DMR/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* each section of quoted text to
which they relate. Unappreciated followup styles are referred to as
"top-posting", "Jeopardy" (because the answer comes before the
question), or "TOFU" (Text Over, Fullquote Under).
Reversing the chronology of the dialog makes it much harder to
understand (some folks won't even read it if written in that style).
For more information on quoting style, see:
http://web.presby.edu/~nnqadmin/nnq/nquote.html
Speak Perl rather than English, when possible
Perl is much more precise than natural language. Saying it in Perl
instead will avoid misunderstanding your question or problem.
Do not say: I have variable with "foo\tbar" in it.
Instead say: I have $var = "foo\tbar", or I have $var = 'foo\tbar',
or I have $var = <DATA> (and show the data line).
Ask perl to help you
You can ask perl itself to help you find common programming mistakes
by doing two things: enable warnings (perldoc warnings) and enable
"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
newsgroup without first seeing if a machine can help you find your
problem. It is demeaning to be asked to do the work of a machine. It
will annoy the readers of your article.
You can look up any of the messages that perl might issue to find
out what the message means and how to resolve the potential mistake
(perldoc perldiag). If you would like perl to look them up for you,
you can put "use diagnostics;" near the top of your program.
Do not re-type Perl code
Use copy/paste or your editor's "import" function rather than
attempting to type in your code. If you make a typo you will get
followups about your typos instead of about the question you are
trying to get answered.
Provide enough information
If you do the things in this item, you will have an Extremely Good
chance of getting people to try and help you with your problem!
These features are a really big bonus toward your question winning
out over all of the other posts that you are competing with.
First make a short (less than 20-30 lines) and *complete* program
that illustrates the problem you are having. People should be able
to run your program by copy/pasting the code from your article. (You
will find that doing this step very often reveals your problem
directly. Leading to an answer much more quickly and reliably than
posting to Usenet.)
Describe *precisely* the input to your program. Also provide example
input data for your program. If you need to show file input, use the
__DATA__ token (perldata.pod) to provide the file contents inside of
your Perl program.
Show the output (including the verbatim text of any messages) of
your program.
Describe how you want the output to be different from what you are
getting.
If you have no idea at all of how to code up your situation, be sure
to at least describe the 2 things that you *do* know: input and
desired output.
Do not provide too much information
Do not just post your entire program for debugging. Most especially
do not post someone *else's* entire program.
Do not post binaries, HTML, or MIME
clpmisc is a text only newsgroup. If you have images or binaries
that explain your question, put them in a publically accessible
place (like a Web server) and provide a pointer to that location. If
you include code, cut and paste it directly in the message body.
Don't attach anything to the message. Don't post vcards or HTML.
Many people (and even some Usenet servers) will automatically filter
out such messages. Many people will not be able to easily read your
post. Plain text is something everyone can read.
Social faux pas to avoid
The first two below are symptoms of lots of FAQ asking here in clpmisc.
It happens so often that folks will assume that it is happening yet
again. If you have looked but not found, or found but didn't understand
the docs, say so in your article.
Asking a Frequently Asked Question
It should be understood that you may have missed the applicable FAQ
when you checked, which is not a big deal. But if the Frequently
Asked Question is worded similar to your question, folks will assume
that you did not look at all. Don't become indignant at pointers to
the FAQ, particularly if it solves your problem.
Asking a question easily answered by a cursory doc search
If folks think you have not even tried the obvious step of reading
the docs applicable to your problem, they are likely to become
annoyed.
If you are flamed for not checking when you *did* check, then just
shrug it off (and take the answer that you got).
Asking for emailed answers
Emailed answers benefit one person. Posted answers benefit the
entire community. If folks can take the time to answer your
question, then you can take the time to go get the answer in the
same place where you asked the question.
It is OK to ask for a *copy* of the answer to be emailed, but many
will ignore such requests anyway. If you munge your address, you
should never expect (or ask) to get email in response to a Usenet
post.
Ask the question here, get the answer here (maybe).
Beware of saying "doesn't work"
This is a "red flag" phrase. If you find yourself writing that,
pause and see if you can't describe what is not working without
saying "doesn't work". That is, describe how it is not what you
want.
Sending a "stealth" Cc copy
A "stealth Cc" is when you both email and post a reply without
indicating *in the body* that you are doing so.
Be extra cautious when you get upset
Count to ten before composing a followup when you are upset
This is recommended in all Usenet newsgroups. Here in clpmisc, most
flaming sub-threads are not about any feature of Perl at all! They
are most often for what was seen as a breach of netiquette. If you
have lurked for a bit, then you will know what is expected and won't
make such posts in the first place.
But if you get upset, wait a while before writing your followup. I
recommend waiting at least 30 minutes.
Count to ten after composing and before posting when you are upset
After you have written your followup, wait *another* 30 minutes
before committing yourself by posting it. You cannot take it back
once it has been said.
AUTHOR
Tad McClellan <tadmc@augustmail.com> and many others on the
comp.lang.perl.misc newsgroup.
------------------------------
Date: Tue, 22 Aug 2006 10:41:22 +0200
From: "Ferry Bolhar" <bol@adv.magwien.gv.at>
Subject: Question about UNIVERSAL
Message-Id: <1156236083.245104@proxy.dienste.wien.at>
Hi,
while looking at the code of 'Attribute::Handlers' (just for couriosity),
I encountered this code fragment:
*{"Attribute::Handlers::UNIVERSAL::MODIFY_${_}_ATTRIBUTES"} =
_gen_handler_AH_ foreach @{$validtype{ANY}};
IIRC, this will create named subroutines "MODIFY_xxx_ATTRIBUTES"
(where "xxx" is "SCALAR, "ARRAY", "HASH" and "CODE") in package
"Attribute::Handlers::UNIVERSAL". These wiil be "attribute handlers" for
the particular value types.
In the next line, I saw this code:
push @UNIVERSAL::ISA, 'Attribute::Handlers::UNIVERSAL'
unless grep /^Attribute::Handlers::UNIVERSAL$/, @UNIVERSAL::ISA;
This will push class "Attribute::Handlers::UNIVERSAL" (and so the methods
defined above) into UNIVERSAL's @ISA array.
Until now, I thought that, if Perl cannot find a method, it will look as
last chance
in package UNIVERSAL. Therefore, if one writes
package UNIVERSAL;
sub MySub {...};
"MySub" will be used if a method named "MySub" cannot be found in a class
or all inherited classes.
But I thought there is one and only one class named "UNIVERSAL"! What
about class "Attribute::Handlers::UNIVERSAL"? Will this be a different
UNIVERSAL class? Another "last chance" to look up for methods?
And does the ISA-mechanism apply to UNIVERSAL as well? If one writes
push @UNIVERSAL::ISA, "AnotherClass";
does Perl look in "UNIVERSAL" and then in "AnotherClass" as well as
last chance? Couldn't cause this cyclic endless lookups?
Can someone explain the purpose of these commands?
Many thanks for all answers, and kind greetings
Ferry
--
Ing. Ferry Bolhar
Municipality of Vienna, Department 14
A-1010 Vienna / AUSTRIA
E-mail: bol@adv.magwien.gv.at
------------------------------
Date: 21 Aug 2006 19:23:22 -0700
From: "Brett.R.Davis@gmail.com" <Brett.R.Davis@gmail.com>
Subject: Re: Use of uninitialized value in string eq at ./xml_simple line 154.
Message-Id: <1156213402.327651.116840@75g2000cwc.googlegroups.com>
thanks - I wouldn't have put this on the board had i not tried that....
Matt Garrish wrote:
> Brett.R.Davis@gmail.com wrote:
>
> > I can't seem to get rid of this message :
> >
> > Use of uninitialized value in string eq at ./xml_simple line 154.
> >
> > Please see code below.
> >
> > The message isn't helpful, and i have tried to understand it using
> > "diagnostics, strict, and warnings".
> >
>
> It means what it says, which is that you're attempting to compare
> values using the eq operator and one or both of the scalars is
> undefined. That it's reported at the beginning of the block means you
> have to figure out which of the comparisons inside has the undefined
> value and either give it a default value before using it, or if you
> really don't care, turn of the warnings for that block.
>
> Matt
------------------------------
Date: 21 Aug 2006 19:39:40 -0700
From: "Brett.R.Davis@gmail.com" <Brett.R.Davis@gmail.com>
Subject: Re: Use of uninitialized value in string eq at ./xml_simple line 154.
Message-Id: <1156214380.056926.52190@74g2000cwt.googlegroups.com>
Thanks - the information is helpful
Paul Lalli wrote:
> Brett.R.Davis@gmail.com wrote:
> > I can't seem to get rid of this message :
> >
> > Use of uninitialized value in string eq at ./xml_simple line 154.
> >
> > Please see code below.
> >
> > The message isn't helpful, and i have tried to understand it using
> > "diagnostics, strict, and warnings".
>
> It's telling you that one of the two values that you are comparing with
> the eq operator on line 154 is undefined.
>
> > #initialized here
> > my $device_id_found=0;
> > for ($index = $cdef_row; $index <= $ib_matrix_max_rows;
> > $index = $index + 1) {
> > if ($device_id_found == 3) { $index =
> > $ib_matrix_max_rows; }
> > line 154 -> if ($device_id_found > 0) {
> > if (($ib_matrix_copy[$index][0] eq "regf")) {
> > if
> > ($ib_matrix_copy[$index][$column_headings{'IC'}] eq "VER") {
> > $device_ib_version =
> > $ib_matrix_copy[$index][$part_column];
> > print "INFO : IB Version Found
> > $device_ib_version\n";
> > $device_id_found =
> > $device_id_found + 1;
> > }
> > elsif
> > ($ib_matrix_copy[$index][$column_headings{'IC'}] eq "FAM") {
> > $device_family =
> > $ib_matrix_copy[$index][$part_column];
> > print "INFO : Device Family Found
> > : $device_family\n";
> > $device_id_found =
> > $device_id_found + 1;
>
> Well, which one of these lines is line 154? I count three separate eq
> comparison in this code, two of which use the same variable. So one of
> these variables is undefined:
> $ib_matrix_copy[$index][0]
> $ib_matrix_copy[$index][$column_headings{'IC'}]
>
> Figure out which line Perl is complaining about, and then debug until
> you figure out why that variable is undefined.
>
> Paul Lalli
------------------------------
Date: 21 Aug 2006 19:40:51 -0700
From: "Brett.R.Davis@gmail.com" <Brett.R.Davis@gmail.com>
Subject: Re: Use of uninitialized value in string eq at ./xml_simple line 154.
Message-Id: <1156214451.240538.25130@m79g2000cwm.googlegroups.com>
OK - it can be any code inside the "block"
That makes more sense - I kept trying to narrow it down to line 154.
I'll try and let you know.
Brett.R.Davis@gmail.com wrote:
> thanks - I wouldn't have put this on the board had i not tried that....
>
>
> Matt Garrish wrote:
> > Brett.R.Davis@gmail.com wrote:
> >
> > > I can't seem to get rid of this message :
> > >
> > > Use of uninitialized value in string eq at ./xml_simple line 154.
> > >
> > > Please see code below.
> > >
> > > The message isn't helpful, and i have tried to understand it using
> > > "diagnostics, strict, and warnings".
> > >
> >
> > It means what it says, which is that you're attempting to compare
> > values using the eq operator and one or both of the scalars is
> > undefined. That it's reported at the beginning of the block means you
> > have to figure out which of the comparisons inside has the undefined
> > value and either give it a default value before using it, or if you
> > really don't care, turn of the warnings for that block.
> >
> > Matt
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
Administrivia:
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------------------------------
End of Perl-Users Digest V10 Issue 9634
***************************************
