[22306] in Perl-Users-Digest
Perl-Users Digest, Issue: 4527 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Feb 7 00:13:34 2003
Date: Thu, 6 Feb 2003 21:11:51 -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 Thu, 6 Feb 2003 Volume: 10 Number: 4527
Today's topics:
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
Re: ppm install GD (on windows) <randy@theoryx5.uwinnipeg.ca>
Re: sharing variables <cyberjeff@sprintmail.com>
Re: Simple regexp gots me stuck... (OJ)
Re: Simple regexp gots me stuck... <mbudash@sonic.net>
Re: The suicide sin (was Re: reference to abc.pl?a=b do Andrew Lee
Re: threaded perl in rh 8.0 <goldbb2@earthlink.net>
Re: Why no perl function to detect numeric or string? <mgjv@tradingpost.com.au>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 06 Feb 2003 22:53:09 -0600
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.3 $)
Message-Id: <KR2dnUXXWq4opt6jXTWcoA@august.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.3 $)
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.perl.com/CPAN-local/authors/Dean_Roehrich/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: Thu, 6 Feb 2003 22:14:15 -0600
From: "Randy Kobes" <randy@theoryx5.uwinnipeg.ca>
Subject: Re: ppm install GD (on windows)
Message-Id: <loG0a.38170$7_.162268@news1.mts.net>
"Tamas" <antal.3(---)@osu.edu> wrote in message
news:b1um4h$ekn$1@charm.magnus.acs.ohio-state.edu...
> I've installed ActiveState perl 5.8.0 (Build 804) along with PPM 3.0 and I
> am not able to install GD nor Tk::PNG with ppm.
We have GD suitable for ActivePerl 8xx in our repository at
http://theoryx5.uwinnipeg.ca/ppms/, which you can access by
setting the repository within the ppm shell to
http://theoryx5.uwinnipeg.ca/cgi-bin/ppmserver?urn:/PPMServer58
I've tried making up Tk::PNG, but although it can compile, the
tests fail.
best regards,
randy kobes
------------------------------
Date: Fri, 07 Feb 2003 02:23:12 GMT
From: Jeff Thies <cyberjeff@sprintmail.com>
Subject: Re: sharing variables
Message-Id: <3E431915.32F441F3@sprintmail.com>
> > I have a configuration file with site variables in it, I call it from
> > my script:
> >
> > require 'variables.var';
>
> Where is this line appearing in your main package? Above or below 'use
> someModule;'?
I've tried it both ways...
>
> >
> > # I also have a module that also needs these variables
> >
> > use someModule;
> > package someModule; # works without this line
>
> Do you have the two above lines of code in the same file?
Nope. someModule looks like:
package someModule;
require variables.var
I'll look through the scoping, I'm rather confused at the moment!
Jeff
------------------------------
Date: 6 Feb 2003 18:59:34 -0800
From: orljustin@aol.com (OJ)
Subject: Re: Simple regexp gots me stuck...
Message-Id: <77d3a68b.0302061859.2977ed3@posting.google.com>
anno4000@lublin.zrz.tu-berlin.de (Anno Siegel) wrote in message news:<b1ui9j$bbg$3@mamenchi.zrz.TU-Berlin.DE>...
> OJ <orljustin@aol.com> wrote in comp.lang.perl.misc:
> > Heya,
> >
> > Can't figure out why this does not return the image path only in $1. Any clue?
> >
> > #!/usr/local/bin/perl
> >
> > $t = "img SRC=\"/Images/tmp.gif\" ALT=\"avast ye scurvy dogs\"";
> > $t=~/src.*?=.*?"(.*)[^ ]?"/i;
> ^^^^
> The underlined part captures everything after '"' up to the last '"' in
> a greedy way, since the following "[^ ]?" is optional.
Hey again,
Why is it optional? I was just going for "the first quote with no
white space before it. Actually, I tried your suggestion below
initially, but got the same result.
oj
>
> > print "\n $1 \n";
> >
> >
> > result:
> > /Images/tmp.gif" ALT="avast ye scurvy dogs
>
> ...as it should. This should work, and is in line with the use of
> non-greedy matching elsewhere:
>
> $t=~/src.*?=.*?"(.*)?"/i;
>
> Not that it's anything like robust...
>
> Anno
------------------------------
Date: Fri, 07 Feb 2003 03:27:36 GMT
From: Michael Budash <mbudash@sonic.net>
Subject: Re: Simple regexp gots me stuck...
Message-Id: <mbudash-590282.19273506022003@typhoon.sonic.net>
In article <77d3a68b.0302061859.2977ed3@posting.google.com>,
orljustin@aol.com (OJ) wrote:
> anno4000@lublin.zrz.tu-berlin.de (Anno Siegel) wrote in message
> news:<b1ui9j$bbg$3@mamenchi.zrz.TU-Berlin.DE>...
> > OJ <orljustin@aol.com> wrote in comp.lang.perl.misc:
> > > Heya,
> > >
> > > Can't figure out why this does not return the image path only in $1. Any
> > > clue?
> > >
> > > #!/usr/local/bin/perl
> > >
> > > $t = "img SRC=\"/Images/tmp.gif\" ALT=\"avast ye scurvy dogs\"";
> > > $t=~/src.*?=.*?"(.*)[^ ]?"/i;
> > ^^^^
> > The underlined part captures everything after '"' up to the last '"' in
> > a greedy way, since the following "[^ ]?" is optional.
>
> Hey again,
>
> Why is it optional?
the question mark specifies it as optional
perldoc perlre
hth-
------------------------------
Date: Thu, 06 Feb 2003 21:53:38 -0500
From: Andrew Lee
Subject: Re: The suicide sin (was Re: reference to abc.pl?a=b does not display as html in N6)
Message-Id: <gd764v8ingtbbkp37vc1i9mlqdirht4b13@4ax.com>
On Wed, 5 Feb 2003 15:36:57 -0600, tadmc@augustmail.com (Tad McClellan)
wrote:
>G.G. Campbell <campbell@cira.colostate.edu> wrote:
>
>> please reply to campbell@cira.colostate.edu
>> as I do not visit here often.
>
>
>So long then.
>
>*plonk*
Did you see my post ... (I have been having trouble with news server and
I'm not sure anyone saw it.)
>please reply to campbell@cira.colostate.edu
>as I do not visit here often.
I assure you, I email you even less often that you visit here.
------------------------------
Date: Thu, 06 Feb 2003 21:36:39 -0500
From: Benjamin Goldberg <goldbb2@earthlink.net>
Subject: Re: threaded perl in rh 8.0
Message-Id: <3E431BB7.EABA1420@earthlink.net>
joe dekk wrote:
>
> When I tried to install DBI on redhat 8.0
> it complains that perl 5.8.0 is compiled with threading
> enabled and gave me warnings about not using threads
> on production environment.
>
> Should I ignore the warnings since none of my perl programs will use
> thread? Is there any bad consequences for using this perl
> even if I won't write any threaded perl? I can compile
> perl and overwrite red hat version but I prefer not doing it.
There *should* be no harm in uses a threaded perl, and not using
threads. Emphasis on "should."
--
"So, who beat the clueless idiot today?"
"Well, we flipped for it, but when Kuno
landed, he wasn't in any shape to fight."
"Next time, try flipping a *coin.*"
------------------------------
Date: Fri, 07 Feb 2003 02:58:07 GMT
From: Martien Verbruggen <mgjv@tradingpost.com.au>
Subject: Re: Why no perl function to detect numeric or string?
Message-Id: <slrnb4685u.se5.mgjv@verbruggen.comdyn.com.au>
[Please, in the future, put your reply _after_ the suitably trimmed
text you reply to]
On Thu, 06 Feb 2003 17:27:07 -0800,
Ed Kulis <ekulis@apple.com> wrote:
> Hi,
>
> I'm curious philosophically, why is perl missing a way to find out if a
> variable is numeric or string?
It isn't missing a way; see the answer to the FAQ. If you're asking
why it doesn't have a builtin operator or function for that; it
doesn't really need one. The Perl data type is a scalar, not an
integer or a string. Perl generally does the right thing depending on
the context you use the scalar in.
> Perl must do it internally to find out if a "==" or an "eq" operation is
> valid.
Yes, but you're certainly not suggesting that Perl exposes all of its
internals to the programmer, are you? As a Perl programmer, the idea
is that you don't worry about it, and you let Perl worry. if you use a
scalar with ==, then Perl will make sure that from then onwards, the
scalar has a numeric component (IV or NV). If you use it with eq, then
perl will make sure that it has a string component (PV).
> Is the type in the symbol table?
No, but if you insist on knowing about it, you can use one of the
modules in the Devel:: name space, for example. However you need to
understand that a Perl scalar does not _have_ a type. It is a bit more
complicated than that. See http://gisle.aas.no/perl/illguts/ and the
perlguts documentation.
In short: A Perl scalar is an SV. An SV can be a SvIV, in which case
it can hold a, possibly unsigned, integer, a SvNV, in which case it
can hold a numeric (double) or SvPV in which case it can hold a
string. As long as an SV is one of these, you can still say that it
has a certain type".
Apart from these, it can also be a SvRV, in which case it holds a
reference. Then, it can also be a SvPVIV or a SvPVNV, which can hold
more than one type of value at the same time, or a SvPVMG, which
attaches magic to the SV. If an SV is one of these, it no longer has a
simple type, and in fact, it can have multiple valid types at the same
time, depending on its history.
Perl automatically converts between these SV types, and upgrades them,
when necessary. it also maintains a state on the individual values in
the structures to see which are valid or not.
> If perl can't do something there's usually some fundamental reason.
The fundamental reason is that it is the wrong question. From Perl's
point of view there is no such thing as a "numeric" scalar. Internally
in Perl, scalars can have numeric fields, which are currently valid or
not, but that is an implementation detail that should not be exposed
to the Perl programmer.
[snip of TOFU quote on FAQ question about subject]
Martien
--
|
Martien Verbruggen | You can't have everything, where would you
Trading Post Australia | put it?
|
------------------------------
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 4527
***************************************
