[26423] in Perl-Users-Digest
Perl-Users Digest, Issue: 8593 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Nov 1 09:05:23 2005
Date: Tue, 1 Nov 2005 06:05:04 -0800 (PST)
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, 1 Nov 2005 Volume: 10 Number: 8593
Today's topics:
Re: Bug in &= (bitwise or) <tassilo.von.parseval@rwth-aachen.de>
Re: Bug in &= (bitwise or) (Anno Siegel)
FAQ 7.20 How do I redefine a builtin function, operator <comdog@pair.com>
Re: List of references <kuujinbo@hotmail.com>
Re: List of references <tim@vegeta.ath.cx>
Re: List of references (Anno Siegel)
Re: PERL/CGI Programmer Wanted <dha@panix.com>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 1 Nov 2005 07:44:46 +0100
From: "Tassilo v. Parseval" <tassilo.von.parseval@rwth-aachen.de>
Subject: Re: Bug in &= (bitwise or)
Message-Id: <3soh74FoshcaU1@news.dfncis.de>
Also sprach Ilya Zakharevich:
> [A complimentary Cc of this posting was sent to
> Tassilo v. Parseval
><tassilo.von.parseval@rwth-aachen.de>], who wrote in article <3snf0uFotcprU1@news.dfncis.de>:
>> After the bitwise-and, the string appears not to be NULL-terminated any
>> longer, at least not at the offset where perl usually finds the NULL
>> termination. That might be confusing the regex engine.
>>
>> For testing what the raw string looks like after the bitwise-and, you
>> can use:
>
> perl -MDevel::Peek -wle "my $a = q(aa); $a &= q(a); print Dump $a"
>
> SV = PV(0x40c64) at 0x40a24
> REFCNT = 1
> FLAGS = (PADBUSY,PADMY,POK,pPOK)
> PV = 0x42020 "a"
> CUR = 1
> LEN = 3
>
> As you can see, PV is not null-terminated. Here is how
> null-terminated stuff is output:
Yes, well, I am aware of Dump() and how a NULL-termination is rendered.
It was after I saw the above output that I became curious and wanted to
see what characters actually were in the PV slot.
To me it seems that the perl core isn't quite sure whether it should
adhere to SvCUR or instead rather believe what is in PV. In any case,
perl obviously gets confused when
SvPVX(sv)[SvCUR(sv)] != '\0'
Did someone already file a bugreport?
Tassilo
--
use bigint;
$n=71423350343770280161397026330337371139054411854220053437565440;
$m=-8,;;$_=$n&(0xff)<<$m,,$_>>=$m,,print+chr,,while(($m+=8)<=200);
------------------------------
Date: 1 Nov 2005 10:09:03 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Bug in &= (bitwise or)
Message-Id: <dk7erv$99e$1@mamenchi.zrz.TU-Berlin.DE>
Tassilo v. Parseval <tassilo.von.parseval@rwth-aachen.de> wrote in comp.lang.perl.misc:
> Did someone already file a bugreport?
I will. Want to check against bleadperl first. I'll also at least go
through the motions of seeing if it has been reported before.
Anno
--
If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers.
------------------------------
Date: Tue, 1 Nov 2005 11:03:00 +0000 (UTC)
From: PerlFAQ Server <comdog@pair.com>
Subject: FAQ 7.20 How do I redefine a builtin function, operator, or method?
Message-Id: <dk7i14$d9s$1@reader2.panix.com>
This message is one of several periodic postings to comp.lang.perl.misc
intended to make it easier for perl programmers to find answers to
common questions. The core of this message represents an excerpt
from the documentation provided with Perl.
--------------------------------------------------------------------
7.20: How do I redefine a builtin function, operator, or method?
Why do you want to do that? :-)
If you want to override a predefined function, such as open(), then
you'll have to import the new definition from a different module. See
"Overriding Built-in Functions" in perlsub. There's also an example in
"Class::Template" in perltoot.
If you want to overload a Perl operator, such as "+" or "**", then
you'll want to use the "use overload" pragma, documented in overload.
If you're talking about obscuring method calls in parent classes, see
"Overridden Methods" in perltoot.
--------------------------------------------------------------------
Documents such as this have been called "Answers to Frequently
Asked Questions" or FAQ for short. They represent an important
part of the Usenet tradition. They serve to reduce the volume of
redundant traffic on a news group by providing quality answers to
questions that keep coming up.
If you are some how irritated by seeing these postings you are free
to ignore them or add the sender to your killfile. If you find
errors or other problems with these postings please send corrections
or comments to the posting email address or to the maintainers as
directed in the perlfaq manual page.
Note that the FAQ text posted by this server may have been modified
from that distributed in the stable Perl release. It may have been
edited to reflect the additions, changes and corrections provided
by respondents, reviewers, and critics to previous postings of
these FAQ. Complete text of these FAQ are available on request.
The perlfaq manual page contains the following copyright notice.
AUTHOR AND COPYRIGHT
Copyright (c) 1997-2002 Tom Christiansen and Nathan
Torkington, and other contributors as noted. All rights
reserved.
This posting is provided in the hope that it will be useful but
does not represent a commitment or contract of any kind on the part
of the contributers, authors or their agents.
------------------------------
Date: Tue, 01 Nov 2005 14:22:51 +0900
From: ko <kuujinbo@hotmail.com>
Subject: Re: List of references
Message-Id: <4366fb7f$1_3@x-privat.org>
ko wrote:
> I'm either missing something basic or haven't found where this is
> documented. (or both) Could someone please point me in the right direction?
>
> use strict;
> use warnings;
>
> # create list of references
> my @a = \my (
> %a, # print statement below => 0
> # %b, # uncomment & print statement below => 2
> );
> print scalar @a . "\n";
>
> keith
I posted this too quickly. Sorry for the noise, it's been a long day...
From perlref, 'Making References', item 2:
As a special case, \(@foo) returns a list of references to the contents
of @foo, not a reference to @foo itself.
------------------------------
Date: Tue, 01 Nov 2005 06:05:53 GMT
From: Tim Hammerquist <tim@vegeta.ath.cx>
Subject: Re: List of references
Message-Id: <slrndme1e0.mbe.tim@vegeta.saiyix>
ko <kuujinbo@hotmail.com> wrote:
> ko wrote:
> > I'm either missing something basic or haven't found where
> > this is documented. (or both) Could someone please point me
> > in the right direction?
> >
> > use strict;
> > use warnings;
> >
> > # create list of references
> > my @a = \my (
> > %a, # print statement below => 0
> > # %b, # uncomment & print statement below => 2
> > );
> > print scalar @a . "\n";
>
> I posted this too quickly. Sorry for the noise, it's been a long day...
>
> From perlref, 'Making References', item 2:
>
> As a special case, \(@foo) returns a list of references to the contents
> of @foo, not a reference to @foo itself.
This isn't what you did, however. You want this, like perlref
says.
my @a = \(%a, %b); # special case as describe in perlref
But you can't do:
my @a = \my (%a, %b); # NOT A SPECIAL CASE!
You're trying to both my() the %a and %b hashes, *and* invoke
the special case, but it won't happen. You'll have to my() the
hashes outside of the ref assignment:
my (%a, %b);
my @a = \(%a, %b);
HTH,
Tim Hammerquist
--
Show me something that beats a Natural Twenty,
and I'll show you hateful LIES!
-- Red Mage, 8-Bit Theater <http://nuklearpower.com/>
------------------------------
Date: 1 Nov 2005 08:45:01 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: List of references
Message-Id: <dk79ud$5ki$1@mamenchi.zrz.TU-Berlin.DE>
Tim Hammerquist <tim@vegeta.ath.cx> wrote in comp.lang.perl.misc:
> ko <kuujinbo@hotmail.com> wrote:
> > As a special case, \(@foo) returns a list of references to the contents
> > of @foo, not a reference to @foo itself.
>
> This isn't what you did, however. You want this, like perlref
> says.
>
> my @a = \(%a, %b); # special case as describe in perlref
>
> But you can't do:
>
> my @a = \my (%a, %b); # NOT A SPECIAL CASE!
>
> You're trying to both my() the %a and %b hashes, *and* invoke
> the special case, but it won't happen. You'll have to my() the
> hashes outside of the ref assignment:
>
> my (%a, %b);
> my @a = \(%a, %b);
That is not so.
my @a = \ my( %a, %b);
puts references to %a and %b in @a, just like
my ( %a, %b);
my @a = \ ( %a, %b);
Anno
--
If you want to post a followup via groups.google.com, don't use
the broken "Reply" link at the bottom of the article. Click on
"show options" at the top of the article, then click on the
"Reply" at the bottom of the article headers.
------------------------------
Date: Tue, 1 Nov 2005 05:55:49 +0000 (UTC)
From: "David H. Adler" <dha@panix.com>
Subject: Re: PERL/CGI Programmer Wanted
Message-Id: <slrndme0r5.d38.dha@panix2.panix.com>
On 2005-10-31, Greg <ggendel@shaw.ca> wrote:
> We're looking for CGI/PERL programmer
You have posted a job posting or a resume in a technical group.
Longstanding Usenet tradition dictates that such postings go into
groups with names that contain "jobs", like "misc.jobs.offered", not
technical discussion groups like the ones to which you posted.
Had you read and understood the Usenet user manual posted frequently to
"news.announce.newusers", you might have already known this. :) (If
n.a.n is quieter than it should be, the relevent FAQs are available at
http://www.faqs.org/faqs/by-newsgroup/news/news.announce.newusers.html)
Another good source of information on how Usenet functions is
news.newusers.questions (information from which is also available at
http://www.geocities.com/nnqweb/).
Please do not explain your posting by saying "but I saw other job
postings here". Just because one person jumps off a bridge, doesn't
mean everyone does. Those postings are also in error, and I've
probably already notified them as well.
If you have questions about this policy, take it up with the news
administrators in the newsgroup news.admin.misc.
http://jobs.perl.org may be of more use to you
Yours for a better usenet,
dha
--
David H. Adler - <dha@panix.com> - http://www.panix.com/~dha/
Riding around on a horse while wearing a loincloth with one's gut
flapping in the breeze for a rock & roll video may lead viewers to
believe said rider to be, if not Indian, merely insane. That confusion
is understandable too. - Rip Thrillby
------------------------------
Date: 01 Nov 2005 09:22:19 GMT
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
Message-Id: <436733ca$0$1764$8b463f8a@news.nationwide.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.5 $)
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://mail.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: 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:
#The Perl-Users Digest is a retransmission of the USENET newsgroup
#comp.lang.perl.misc. For subscription or unsubscription requests, send
#the single line:
#
# subscribe perl-users
#or:
# unsubscribe perl-users
#
#to almanac@ruby.oce.orst.edu.
NOTE: due to the current flood of worm email banging on ruby, the smtp
server on ruby has been shut off until further notice.
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
#To request back copies (available for a week or so), send your request
#to almanac@ruby.oce.orst.edu with the command "send perl-users x.y",
#where x is the volume number and y is the issue number.
#For other requests pertaining to the digest, send mail to
#perl-users-request@ruby.oce.orst.edu. Do not waste your time or mine
#sending perl questions to the -request address, I don't have time to
#answer them even if I did know the answer.
------------------------------
End of Perl-Users Digest V10 Issue 8593
***************************************
