[23539] in Perl-Users-Digest
Perl-Users Digest, Issue: 5747 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Nov 4 06:05:54 2003
Date: Tue, 4 Nov 2003 03:05:08 -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, 4 Nov 2003 Volume: 10 Number: 5747
Today's topics:
Re: derefing a nested table full of refs <member41443@dbforums.com>
grab the last few itmes of an array <tomorro@yesterday.org>
Re: grab the last few itmes of an array <tomorro@yesterday.org>
Re: grab the last few itmes of an array (Anno Siegel)
Making a range from numbers <goth1938@hotmail.com>
Re: Making a range from numbers (Jay Tilton)
Re: Making a range from numbers <goth1938@hotmail.com>
Re: Making a range from numbers <usenet@morrow.me.uk>
Re: Newbie to perl, need help <wizdum.unspam@no-spam.hotmail.com>
Parsing Large Files (Jose Yimpho)
Re: Parsing Large Files (Tad McClellan)
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Re: Rounding a float in Perl? <nospam-abuse@ilyaz.org>
Re: Rounding a float in Perl? (Anno Siegel)
testing for 'undefined subroutine' <tmangner@alphaone.de>
Re: Verbose warnings <invalid-email@rochester.rr.com>
Re: Verbose warnings (Seebs)
Re: Verbose warnings (Seebs)
Re: Verbose warnings (Sam Holden)
Re: Verbose warnings <tassilo.parseval@rwth-aachen.de>
Re: Verbose warnings <tassilo.parseval@rwth-aachen.de>
Re: Verbose warnings (Tad McClellan)
Windows binary with debugging support (JW)
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 4 Nov 2003 02:10:07 GMT
From: AVataRR <member41443@dbforums.com>
Subject: Re: derefing a nested table full of refs
Message-Id: <3555879.1067912200@dbforums.com>
gleh, I feel exactly the same way as you guys. unfortunatley this is for
a little assignment and I have no say in the matter. :( I wonder if I
can get some sort of exemption for that little part, using some sort of
official protest. :D
may oracle and plsql/sql die.
--
Posted via http://dbforums.com
------------------------------
Date: Tue, 04 Nov 2003 19:22:36 +1100
From: asaik <tomorro@yesterday.org>
Subject: grab the last few itmes of an array
Message-Id: <3FA761CC.8000202@yesterday.org>
hello
is there a way I can make an arrayA from the last 3 items of arrayB
where arrayB changes inside a loop?
e.g.
foreach my $i ( @arrB ) {
@arrA = the last 3 items of arrB
$total = total the itmes in arrA
thaks
------------------------------
Date: Tue, 04 Nov 2003 19:40:03 +1100
From: asaik <tomorro@yesterday.org>
Subject: Re: grab the last few itmes of an array
Message-Id: <3FA765E3.1040208@yesterday.org>
asaik wrote:
> hello
> is there a way I can make an arrayA from the last 3 items of arrayB
> where arrayB changes inside a loop?
> e.g.
>
> foreach my $i ( @arrB ) {
> @arrA = the last 3 items of arrB
> $total = total the itmes in arrA
>
> thaks
>
could I
push @arrA for (0..2) @arrB if @arrB > 2;
------------------------------
Date: 4 Nov 2003 09:14:30 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: grab the last few itmes of an array
Message-Id: <bo7qlm$5tr$1@mamenchi.zrz.TU-Berlin.DE>
asaik <news@group.com> wrote in comp.lang.perl.misc:
> asaik wrote:
> > hello
> > is there a way I can make an arrayA from the last 3 items of arrayB
> > where arrayB changes inside a loop?
> > e.g.
> >
> > foreach my $i ( @arrB ) {
> > @arrA = the last 3 items of arrB
> > $total = total the itmes in arrA
That doesn't make much sense. You are trying to take the last three
elements of @arrB as many times as there are elements in @arrB.
If you want to loop over groups of three elements, beginning at the end
of the array, this will do:
while ( @arrB ) {
my @arrA = splice( @arrB, -3, 3);
# do something with @arrA
}
It will only run smoothly if @arrB has a multiple of three elements.
Anno
------------------------------
Date: Tue, 4 Nov 2003 11:55:07 +0800
From: "Just in" <goth1938@hotmail.com>
Subject: Making a range from numbers
Message-Id: <bo77ut$us9$1@news01.intel.com>
Need some peer guidance here, please correct and suggest as necessary.
I have code that generates a hash of arrays through auto vivification. Each
array for each key gets vivified from a file with a range of numbers that
matches a specific condition - for this example lets pick 1-15 (typically it
will be 1-3000).
What I need is to express all numbers in one array as a range if they
increment by 1 per element.
Heres my code:
use strict;
use warnings;
my @Numbers = qw(1 2 3 5 6 8 11 12 13 14);
my @Numbers2 = qw(4 7 9 10 15);
print &FormatNumbers(@Numbers2); # Read that this is deprecated as of perl5,
but still cant find a good reason why
sub FormatNumbers
{
my @In = @_;
my $Return;
my $Str = $In[0];
foreach my $i(1..$#In)
{
unless($In[$i] - $In[$i - 1] == 1)
{
$Str .= "-$In[$i - 1] $In[$i]";
}
$Str .= "-$In[$#In]" if $i == $#In;
}
my @Check = split /\s+/, $Str;
foreach my $i(1..$#Check)
{
if($Check[$i] =~ /^(\d+)-(\d+)/)
{
if($1 == $2) # ? : doesnt seem to work here
{
$Return = "@In";
}
else
{
$Return = "@Check";
}
}
}
return $Return;
}
First thing that seems dumb is that I have to do a check on the output, I'm
sure theres a nifty one line regexp that will suffice for the whole sub.
Next thing you'll note is that for the above the output for both arrays is:
1-3 5-6 8-8 11-14
4 7 9 10 15
8-8 obviously pollutes the desired result. And I'm sure there are other
variations that will mess it up even further, as there is no limitation on
the amount of generated arrays and their respective contents, (except that
each number in the range can be in any of the arrays only once).
Dont really mind what you guys suggest - be it a module, a patch for the
code, or a complete rewrite.
Just in
------------------------------
Date: Tue, 04 Nov 2003 05:21:17 GMT
From: tiltonj@erols.com (Jay Tilton)
Subject: Re: Making a range from numbers
Message-Id: <3fa73607.549893878@news.erols.com>
"Just in" <goth1938@hotmail.com> wrote:
: What I need is to express all numbers in one array as a range if they
: increment by 1 per element.
Check out the Set::IntSpan module.
: Heres my code:
:
: use strict;
: use warnings;
:
: my @Numbers = qw(1 2 3 5 6 8 11 12 13 14);
: my @Numbers2 = qw(4 7 9 10 15);
use Set::IntSpan;
(my $str =
Set::IntSpan
->new( join ',' => @Numbers )
->run_list
) =~ y/,/ /;
print $str;
: print &FormatNumbers(@Numbers2); # Read that this is deprecated as of perl5,
: but still cant find a good reason why
The "&foo()" form of subroutine call is certainly not deprecated, but
the "foo()" form should be preferred unless you know what effects the
leading "&" has and you need those effects.
------------------------------
Date: Tue, 4 Nov 2003 16:38:54 +0800
From: "Just in" <goth1938@hotmail.com>
Subject: Re: Making a range from numbers
Message-Id: <bo7oj3$6b8$1@news01.intel.com>
Thanks for the code and the pointer to the module. I installed it to my
local directory on my Unix box, and it runs like a charm.
-----8<--------------------
> ->new( join ',' => @Numbers )
-----8<--------------------
Had to change the => to a , in order to get it to work though.
-----8<--------------------
> The "&foo()" form of subroutine call is certainly not deprecated, but
> the "foo()" form should be preferred unless you know what effects the
> leading "&" has and you need those effects.
-----8<--------------------
Care to expand on what the effects are?
Cheers
Just in
------------------------------
Date: Tue, 4 Nov 2003 09:30:16 +0000 (UTC)
From: Ben Morrow <usenet@morrow.me.uk>
Subject: Re: Making a range from numbers
Message-Id: <bo7rj8$b3k$1@wisteria.csv.warwick.ac.uk>
"Just in" <goth1938@hotmail.com> wrote:
> Thanks for the code and the pointer to the module. I installed it to my
> local directory on my Unix box, and it runs like a charm.
> > ->new( join ',' => @Numbers )
> Had to change the => to a , in order to get it to work though.
Huh? Which version of perl are you running?
'=>' should be the same as ',', except that if its left argument is a
bareword it will be stringified.
> > The "&foo()" form of subroutine call is certainly not deprecated, but
> > the "foo()" form should be preferred unless you know what effects the
> > leading "&" has and you need those effects.
> Care to expand on what the effects are?
Read perldoc perlsub, the paragraph starting 'A subroutine may be
called using an explicit "&" prefix.'.
Ben
--
The cosmos, at best, is like a rubbish heap scattered at random.
- Heraclitus
ben@morrow.me.uk
------------------------------
Date: Mon, 3 Nov 2003 23:00:25 -0500
From: "Samurai Jesus" <wizdum.unspam@no-spam.hotmail.com>
Subject: Re: Newbie to perl, need help
Message-Id: <bo788u$5ov4$1@netnews.upenn.edu>
Stuart,
Thanks for the pointers. I was able to figure out the procedure, and I will
post my results when I've got it completely figured out. Again, thanks for
all your help.
-SJ
"Stuart Moore" <stjm2@cam.ac.uk.remove> wrote in message
news:bo5egs$qai$1@pegasus.csx.cam.ac.uk...
>
> Samurai Jesus wrote:
>
> > Hi. I was hoping that someone with more experience in perl could help
me
> > out.
> >
> > I'm trying to come up with a perl script that will reside on one of my
> > systems to change the names of directories on a NetApp Filer. I connect
to
> > the filer using rsh.
> >
> > I have to be able to change the names of directories on the filer.
> >
> > Currently the directories have names that are totally useless, and I
have to
> > change them to something useful, using the access time stamp as the name
of
> > the directory. As it is, I know that the $atime component of
> > stat($filename) should give me the access time of the directory, and the
> > command to change the directory name is "snap rename <volume name>
> > <directory name> <new directory name>"
> >
> > I'm hoping that someone can help point me in the correct direction.
>
> Build up the new directory name using stat (and possibly looking at
> localtime) - see the documentation for both in perlfunc.
>
> Then use system to call the "snap" command - again, see perlfunc.
>
> HTH
>
> Stuart
>
------------------------------
Date: 3 Nov 2003 22:16:06 -0800
From: swimmar@hotmail.com (Jose Yimpho)
Subject: Parsing Large Files
Message-Id: <756e20ad.0311032216.5593b504@posting.google.com>
Perl newbie here.. I'm experienced with other languages, but this is
my first grapple with Perl + Regular Expressions, and I could use some
help or a starting point on this problem.
I have a text file that contains lines like what's at the bottom of
this message. I would like to create a new file that contained
comma-separated values that contains the info from the file. Possible
entries are company name, street address, city, state, zip, phone,
fax, email, url, rep, membership type, business type, and major
products.
Thanks for your help,
Joe Laughlin
----------------------------------------
A Street Games
489 Park Ave
Idaho Idaho Falls ID 83402
Phone: 208-542-2824 Fax: 208-542-2824
manton00@aol.com
Business Representative: Mike Antonson
Membership Type: C - Ret
Business type: Accessories, Board games, Collectable card games,
Family
games, Magazines, Miniatures, Retailer, Roleplaying games, Video
games,
Wargames, Comic Books
Major products: Role-Playing Games, Games Workshop Products, CCGs
2 Big Guyz
15901 Indian Head Hwy
Accokeek MD 20607
Phone: 240-210-0302
andy@2bigguyz.com
www.2bigguyz.com
Business Representative: Andrew Turlington
Membership Type: C - Ret
Business type: Accessories, Board games, Books, Collectable card
games,
Magazines, Miniatures, Retailer, Wargames, Comic Books
21st Century Comics
1531 S Harbor Blvd
Fullerton CA 92832
Phone: 714-992-6649 Fax: 714-992-6604
21stccomics@prodigy.net
www.21stcenturycomics.com
Business Representative: Barry Short
Membership Type: C - Ret
Business type: Accessories, Books, Collectable card games, Other card
games,
Miniatures, Retailer, Roleplaying games, Wargames
Major products: Wizards of the Coast Products; Wizkids Products
-------------------------------------
------------------------------
Date: Tue, 4 Nov 2003 01:13:05 -0600
From: tadmc@augustmail.com (Tad McClellan)
Subject: Re: Parsing Large Files
Message-Id: <slrnbqekc1.inp.tadmc@magna.augustmail.com>
Jose Yimpho <swimmar@hotmail.com> wrote:
> Subject: Parsing Large Files
I see nothing relating to large files in your post, so why
did you say that there would be something relating to large
files in your Subject?
> Perl newbie here.. I'm experienced with other languages, but this is
> my first grapple with Perl + Regular Expressions, and I could use some
> help or a starting point on this problem.
You haven't told us enough to be of much help...
> I have a text file that contains lines like what's at the bottom of
> this message.
To parse a file we need to know the rules that the file will follow.
What rules will the file follow?
> Possible
Which ones are optional?
Which ones are required?
> entries are company name,
Is that always the 1st line?
> street address,
Is that always the 2nd line?
> phone,
Does that one always start with "Phone:" ?
> email,
Is that always the 5th line?
> url,
(you know those aren't really URLs, right?)
> rep, membership type, business type, and major
> products.
Do those ones always have the something-ending-with-colon headings?
> Business type: Accessories, Board games, Collectable card games,
> Family
> games, Magazines, Miniatures, Retailer, Roleplaying games, Video
> games,
> Wargames, Comic Books
Even worse than the sample-with-no-spec approach to getting help
is letting your newsreader break the data for you.
Is that all on one line in your Real Data?
Maybe this will get you started:
---------------------------
#!/usr/bin/perl
use strict;
use warnings;
{ local $/ = ''; # enable paragraph mode
while ( <DATA> ) {
my($name, $street, $addr, $phone, $email) = /(.*)\n/g;
my($city, $state, $zip) = $addr =~ /(.*?)\s+([A-Z][A-Z])\s+(\d+)$/;
my($rep) = /^Business Representative:\s+(.*)/m;
print "$name\n$street\n$city - $state - $zip\n$rep\n";
print "-----\n";
}
}
__DATA__
# your data here
---------------------------
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Tue, 04 Nov 2003 02:22:08 -0600
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.4 $)
Message-Id: <Q8mdncYtlYEt_DqiRVn-vg@august.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.4 $)
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.
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
"Jeopardy" (because the answer comes before the question), or
"TOFU".
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, 4 Nov 2003 05:01:30 +0000 (UTC)
From: Ilya Zakharevich <nospam-abuse@ilyaz.org>
Subject: Re: Rounding a float in Perl?
Message-Id: <bo7bra$1av1$1@agate.berkeley.edu>
[A complimentary Cc of this posting was sent to
Anno Siegel
<anno4000@lublin.zrz.tu-berlin.de>], who wrote in article <bnivfs$i76$1@mamenchi.zrz.TU-Berlin.DE>:
> The FAQ answer is "use sprintf()", which is fine in most cases. It
> must be said, however, that sprintf() is a slow function, and if a
> lot of rounding is going on it can easily dominate the calculation.
> Even a pure Perl rounding function, along the lines of
>
> sub round {
> my $x = shift;
> my $y = 0.5 + abs $x;
> my $abs = int $y;
> $abs -= $abs % 2 if $y == $abs;
> ($x <=> 0) * $abs;
> }
Today I sent a patch which sped up sprint "%.0f" 15x.
Hope this slightly compensates my goof with having a constant-folded
benchmark ;-),
Ilya
------------------------------
Date: 4 Nov 2003 08:23:34 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: Rounding a float in Perl?
Message-Id: <bo7nm6$3qn$1@mamenchi.zrz.TU-Berlin.DE>
Ilya Zakharevich <nospam-abuse@ilyaz.org> wrote in comp.lang.perl.misc:
> [A complimentary Cc of this posting was sent to
> Anno Siegel
> <anno4000@lublin.zrz.tu-berlin.de>], who wrote in article
> <bnivfs$i76$1@mamenchi.zrz.TU-Berlin.DE>:
> > The FAQ answer is "use sprintf()", which is fine in most cases. It
> > must be said, however, that sprintf() is a slow function, and if a
> > lot of rounding is going on it can easily dominate the calculation.
> > Even a pure Perl rounding function, along the lines of
> >
> > sub round {
> > my $x = shift;
> > my $y = 0.5 + abs $x;
> > my $abs = int $y;
> > $abs -= $abs % 2 if $y == $abs;
> > ($x <=> 0) * $abs;
> > }
>
> Today I sent a patch which sped up sprint "%.0f" 15x.
Ah... that's about as fast as it gets. Now we can promote the FAQ answer
to rounding in good conscience.
> Hope this slightly compensates my goof with having a constant-folded
> benchmark ;-),
Well, it happens. When Perl 5 was new, I presented a benchmark to p5p,
proving that an extensive patch to the % operator didn't cost any time
at all. Both sides of the benchmark where constant-folded. Larry had
to set me straight.
Anno
------------------------------
Date: Tue, 04 Nov 2003 12:00:45 +0100
From: Torsten Mangner <tmangner@alphaone.de>
Subject: testing for 'undefined subroutine'
Message-Id: <bo80su$19t758$2@ID-107673.news.uni-berlin.de>
Hi group,
i need a capability (via a skript or something) to test my skripts (at
compile time), if all subroutines that are called in the programm are
really defined or 'use'd.
thanks,
Torsten
--
Torsten Mangner
http://www.alphaone.de
I'm not lost, I'm directionally challenged.
------------------------------
Date: Tue, 04 Nov 2003 02:16:16 GMT
From: Bob Walton <invalid-email@rochester.rr.com>
Subject: Re: Verbose warnings
Message-Id: <3FA70A7E.8060900@rochester.rr.com>
Seebs wrote:
> Is there any way to find out WHICH variable is uninitialized, short of
> breaking a line up into bunches of single lines?
>
> I inherited a HUGE script full of lines that look roughly like
>
> $value = "$value1$value2$value3<a href="$value4"
> fgcolor="$value5">$value6</a><font size="$value7">..."
> which are trying to build HTML from *HORDES* of values.
>
> I probably have, say, five hundred of these little buggers to catch.
>
> I would be *deleriously* happy to discover a warning switch that would
> cause perl to say "Use of uninitialized value (variable $value3)" or
> something similar.
>
> Perl is 5.6.1; I could probably use 5.8 without much trouble, but I don't
> want to switch right now if I don't have to.
>
> -s
>
You don't say if your variables are package variables or lexicals. If
they are all package variables, you could peruse the symbol table, maybe
something like:
for(sort keys %main::){
no strict 'refs'; #probably not needed if package variables :-(
print "$_ is uninitialized\n" unless defined $$_;
}
You will have to skip the extraneous stuff in the listing which isn't
your variables, such as all the builtin variables that default to undef,
filehandles, etc, but once those are ignored, it should give you a
listing of your uninitialized scalar variables (but it will include any
that were initialized to the undef value :-)). It won't give you any
lexicals, though. Or any anonymous scalars.
If your variable names are as structured as your example shows, you
could test for names like that in the above loop, like:
next unless /^value\d+$/;
ahead of the print.
If your variables are all lexicals, you could temporarily comment the
"my" or "our" definitions and the use strict;, and do the same thing.
HTH.
--
Bob Walton
Email: http://bwalton.com/cgi-bin/emailbob.pl
------------------------------
Date: 04 Nov 2003 02:20:30 GMT
From: seebs@plethora.net (Seebs)
Subject: Re: Verbose warnings
Message-Id: <3fa70cee$0$1102$3c090ad1@news.plethora.net>
In article <Xns9428D2C97DE58sdn.comcast@216.196.97.136>,
Eric J. Roode <REMOVEsdnCAPS@comcast.net> wrote:
>And then every place there was a
>
> my $foo;
>
>replace it with
>
> tie my $foo, 'MoreWarnings', 'foo';
Oh, if there were declarations for the variables, I'd be set.
The problem is that they're set from a variety of sources, ranging from
evals of configuration files, to other CGI scripts, and so on...
Actually, it turns out that the biggest culprit was a couple of loops that
did
$output .= "$a[$x]";
in a loop to about 10 more than there were elements of a... "harmless", but
it cluttered up my log files something fierce.
I promise you that any perl code I ever try to deliver, to anyone, whether
commercial or off-the-cuff, will be built and tested with "perl -w".
I think I've done a good 20 hours of work on this program just trying to get
the undefined variable references cleaned up so I can read the rest of the
warnings and errors.
-s
--
Copyright 2003, all wrongs reversed. Peter Seebach / seebs@plethora.net
http://www.seebs.net/log/ - YA blog. http://www.seebs.net/ - homepage.
C/Unix wizard, pro-commerce radical, spam fighter. Boycott Spamazon!
Consulting, computers, web hosting, and shell access: http://www.plethora.net/
------------------------------
Date: 04 Nov 2003 02:52:34 GMT
From: seebs@plethora.net (Seebs)
Subject: Re: Verbose warnings
Message-Id: <3fa71472$0$96347$3c090ad1@news.plethora.net>
In article <3FA70A7E.8060900@rochester.rr.com>,
Bob Walton <totally@bogus.email.invalid> wrote:
>You don't say if your variables are package variables or lexicals. If
>they are all package variables, you could peruse the symbol table, maybe
>something like:
Yup.
But what I really *want* is an option to have perl emit any kind of
information at all about what the expression that yielded undef *looked*
like. I guess, my goal was, if possible, to find a way to do this that
could be used on arbitrary new code, preferably by sending perl a flag,
rather than modifying the code.
I recognize that it's not always a variable, but it seems like it would
be cheap to, when producing that warning, see whether it *is* a variable.
-s
--
Copyright 2003, all wrongs reversed. Peter Seebach / seebs@plethora.net
http://www.seebs.net/log/ - YA blog. http://www.seebs.net/ - homepage.
C/Unix wizard, pro-commerce radical, spam fighter. Boycott Spamazon!
Consulting, computers, web hosting, and shell access: http://www.plethora.net/
------------------------------
Date: 4 Nov 2003 03:24:46 GMT
From: sholden@flexal.cs.usyd.edu.au (Sam Holden)
Subject: Re: Verbose warnings
Message-Id: <slrnbqe6vn.t1q.sholden@flexal.cs.usyd.edu.au>
On 04 Nov 2003 02:52:34 GMT, Seebs <seebs@plethora.net> wrote:
> In article <3FA70A7E.8060900@rochester.rr.com>,
> Bob Walton <totally@bogus.email.invalid> wrote:
>>You don't say if your variables are package variables or lexicals. If
>>they are all package variables, you could peruse the symbol table, maybe
>>something like:
>
> Yup.
>
> But what I really *want* is an option to have perl emit any kind of
> information at all about what the expression that yielded undef *looked*
> like. I guess, my goal was, if possible, to find a way to do this that
> could be used on arbitrary new code, preferably by sending perl a flag,
> rather than modifying the code.
>
> I recognize that it's not always a variable, but it seems like it would
> be cheap to, when producing that warning, see whether it *is* a variable.
The debugger will at least allow you to break at the line indicated by
a warning and examine the state of the variables used in the expression.
I'm not sure if there is a standard way of getting it to act as
if it hit a breakpoint on a warning, but if you know the line number
you can break at that line and check the variables used before the
warning occurs.
If it's in a loop then you could do something like:
---test.pl---
my ($x,$y) = (1);
print "$x\n";
print "$y\n";
print "$x\n";
---test.pl---
; perl -w test.pl
1
Use of uninitialized value in concatenation (.) or string at test.pl line 3.
1
; perl -dw test.pl
; perl -dw test.pl
Loading DB routines from perl5db.pl version 1.22
Editor support available.
Enter h or `h h' for help, or `man perldebug' for more help.
main::(test.pl:1): my ($x,$y) = (1);
DB<1> $SIG{__WARN__} = sub {$::WARNING = 1;warn @_}
DB<2> b 4 $::WARNING
DB<3> c
1
Use of uninitialized value in concatenation (.) or string at test.pl line 3.
main::(test.pl:4): print "$x\n";
DB<4> v 3
1: my ($x,$y) = (1);
2: print "$x\n";
3: print "$y\n";
4==>b print "$x\n";
5
DB<5> x $y
0 undef
It's annoying to have to break after the line causing the warning, but I
don't know the debugger well enough to now if you can make it break
after a warning.
--
Sam Holden
------------------------------
Date: 4 Nov 2003 06:29:56 GMT
From: "Tassilo v. Parseval" <tassilo.parseval@rwth-aachen.de>
Subject: Re: Verbose warnings
Message-Id: <bo7h14$rr7$1@nets3.rz.RWTH-Aachen.DE>
Also sprach Tad McClellan:
> Tassilo v. Parseval <tassilo.parseval@rwth-aachen.de> wrote:
>> Also sprach Tad McClellan:
>>
>>> Seebs <seebs@plethora.net> wrote:
>>>> Is there any way to find out WHICH variable is uninitialized, short of
>>>> breaking a line up into bunches of single lines?
>>>
>>>
>>> Yes, if they are package (dynamic) variables.
>>
>> How so?
>
>
> I think you were thinking that I was answering the question
> that I trimmed, rather than the question that I quoted?
Guilty as charged, I still had the original posting as a whole in my
short-term memory.
>> ethan@ethan:~$ perl -w
>> use vars qw/$c $d $e $f/;
>> $e = 1;
>> print "$c;$d;$e;$f\n";
>> __END__
>> Use of uninitialized value in concatenation (.) or string at - line 3.
>> Use of uninitialized value in concatenation (.) or string at - line 3.
>> Use of uninitialized value in concatenation (.) or string at - line 3.
>> ;;1;
>
>
>> At least up to (and including) 5.8.1, the behaviour seems to be
>> independent from using lexicals or dynamic variables.
>
>
> Yes, but if they are dynamic variables, then we can use symrefs
> and stay "short of breaking a line up into bunches of single lines".
Oh. The chance that you'd suggest symrefs is so marginal that I never
even considered it. :-) Kind of explains why you didn't provide the code
in the first place.
Tassilo
--
$_=q#",}])!JAPH!qq(tsuJ[{@"tnirp}3..0}_$;//::niam/s~=)]3[))_$-3(rellac(=_$({
pam{rekcahbus})(rekcah{lrePbus})(lreP{rehtonabus})!JAPH!qq(rehtona{tsuJbus#;
$_=reverse,s+(?<=sub).+q#q!'"qq.\t$&."'!#+sexisexiixesixeseg;y~\n~~dddd;eval
------------------------------
Date: 4 Nov 2003 07:05:45 GMT
From: "Tassilo v. Parseval" <tassilo.parseval@rwth-aachen.de>
Subject: Re: Verbose warnings
Message-Id: <bo7j49$t4t$1@nets3.rz.RWTH-Aachen.DE>
Also sprach Eric J. Roode:
> seebs@plethora.net (Seebs) wrote in news:3fa6ba78$0$1100$3c090ad1
> @news.plethora.net:
>
>> Is there any way to find out WHICH variable is uninitialized, short of
>> breaking a line up into bunches of single lines?
>>
>> I inherited a HUGE script full of lines that look roughly like
>>
>> $value = "$value1$value2$value3<a href="$value4"
>> fgcolor="$value5">$value6</a><font size="$value7">..."
>> which are trying to build HTML from *HORDES* of values.
>>
>> I probably have, say, five hundred of these little buggers to catch.
>
> 500 statements? or 500 variables?
>
> The solution that occurs to me is to tie each variable to a class that
> gives more information when its (undefined) value is fetched. Something
> like:
[...]
For many variables that will require quite a bit of changes to the code.
I was just experimenting with changing the value of PL_sv_undef and
indeed, this seems to be possible using XS. It's a little dangerous
and flaky really, but at least temporarily it can be done:
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "ppport.h"
SV old;
int defined;
MODULE = undef PACKAGE = undef
void
restore_undef()
CODE:
if (defined) {
memcpy(&PL_sv_undef, &old, sizeof(old));
defined = 0;
}
void
define_undef()
CODE:
/* save original undef */
memcpy(&old, &PL_sv_undef, sizeof(PL_sv_undef));
SvREADONLY_off(&PL_sv_undef);
SvUPGRADE(&PL_sv_undef, SVt_PV);
sv_setpvn(&PL_sv_undef, "<undef>", 7);
defined = 1;
ethan@ethan:/tmp/undef$ perl -w -Mblib -Mundef
undef::define_undef();
print "*", undef, "\n";
undef::restore_undef();
print "*", undef, "\n";
__END__
*<undef>
Use of uninitialized value in print at - line 4.
*
This doesn't quite solve the problem of getting the name of the variable
that holds an undefined value. But it makes the undefinedness visible
and only requires minimal additions to the code.
Tassilo
--
$_=q#",}])!JAPH!qq(tsuJ[{@"tnirp}3..0}_$;//::niam/s~=)]3[))_$-3(rellac(=_$({
pam{rekcahbus})(rekcah{lrePbus})(lreP{rehtonabus})!JAPH!qq(rehtona{tsuJbus#;
$_=reverse,s+(?<=sub).+q#q!'"qq.\t$&."'!#+sexisexiixesixeseg;y~\n~~dddd;eval
------------------------------
Date: Tue, 4 Nov 2003 00:52:58 -0600
From: tadmc@augustmail.com (Tad McClellan)
Subject: Re: Verbose warnings
Message-Id: <slrnbqej6a.inp.tadmc@magna.augustmail.com>
Tassilo v. Parseval <tassilo.parseval@rwth-aachen.de> wrote:
> The chance that you'd suggest symrefs is so marginal that I never
> even considered it. :-) Kind of explains why you didn't provide the code
> in the first place.
I knew it would make me feel dirty, and wanted to avoid that if possible.
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: 3 Nov 2003 21:11:02 -0800
From: jweed@justicepoetic.net (JW)
Subject: Windows binary with debugging support
Message-Id: <ad5599ed.0311032111.20d69da4@posting.google.com>
Hello,
Because I have had many problems trying to compile perl on my WinME
box, I was wondering if anyone knew of a good binary distro for
windows which was compiled with Debugging support. 5.8.1 preferred.
Thank you for your time,
JW
------------------------------
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>
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------------------------------
End of Perl-Users Digest V10 Issue 5747
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