[32179] in Perl-Users-Digest
Perl-Users Digest, Issue: 3444 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Jul 15 06:09:35 2011
Date: Fri, 15 Jul 2011 03:09:17 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Fri, 15 Jul 2011 Volume: 11 Number: 3444
Today's topics:
Re: How do I know I am running on Windows command line <mickey@perusion.net>
Re: How do I know I am running on Windows command line <marc.girod@gmail.com>
Re: How do I know I am running on Windows command line <justin.1104@purestblue.com>
Re: How do I know I am running on Windows command line <tzz@lifelogs.com>
Re: How do I know I am running on Windows command line <RedGrittyBrick@spamweary.invalid>
Re: How do I know I am running on Windows command line <justin.1104@purestblue.com>
Re: Perl hashes and structs question <tzz@lifelogs.com>
Re: Perl hashes and structs question <cartercc@gmail.com>
Re: Perl hashes and structs question <rweikusat@mssgmbh.com>
Re: Perl hashes and structs question <tzz@lifelogs.com>
Perl Multitasking Question <edgrsprj@ix.netcom.com>
Re: Perl Multitasking Question <RedGrittyBrick@spamweary.invalid>
Pod::Parser vs Pod::Simple <ralph@happydays.com>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@seesig.invalid
Re: remove undefined values witout warnings <marc.girod@gmail.com>
Re: remove undefined values witout warnings <tzz@lifelogs.com>
Re: remove undefined values witout warnings <jl_post@hotmail.com>
Re: test two hash(refs) for equality <tzz@lifelogs.com>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 13 Jul 2011 22:19:32 -0500
From: Mickey Langan <mickey@perusion.net>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <slrnj1so24.jeh.mickey@bill.heins.net>
On 2011-07-13, Aaron Gray <ang.usenet@gmail.com> wrote:
> "Uri Guttman" <uri@StemSystems.com> wrote in message
> news:87aachlsyx.fsf@quad.sysarch.com...
>>>>>>> "AG" == Aaron Gray <ang.usenet@gmail.com> writes:
>>
>> AG> I have an existing perl script that does a "chmod" via "system()".
>>
>> why are you using system when perl has chmod builtin?
>
> Its an existing project I am porting to Windows.
>
>> AG> I need to know I am running on Windows to no do the chmod.
>>
>> check the value of $^O. read perldoc perlvar for more.
>
> Sorry I am very new to Perl so this means nothing to me.
>
>> AG> How do I detect whether perl is being run on the command line ?
>>
>> that is not the same as knowing which OS you are running under. why do
>> you need to know this? and this is running from a command line vs what?
>
> Okay, I think using the builtin chmod is the way forward. How do I do this ?
>
You learn to use perldoc:
perldoc -f chmod
You might start with:
perldoc perl
Then:
perldoc perlwin32
--
Mickey
Experience is what allows you to recognize a mistake the second
time you make it. -- unknown
------------------------------
Date: Thu, 14 Jul 2011 01:12:24 -0700 (PDT)
From: Marc Girod <marc.girod@gmail.com>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <9d0dfab6-3860-45cc-a1b3-836a1c0791ed@a11g2000yqm.googlegroups.com>
On Jul 14, 1:44=A0am, Jim Gibson <jimsgib...@gmail.com> wrote:
> =A0 =A0 =A0 =A0 In Windows platforms, $^O is not very helpful: since it i=
s
> =A0 =A0 =A0 =A0 always "MSWin32"
Thanks for this.
It is always embarrassing how much it takes others to
help reading...
Would however everybody confirm?
Impossible to get e.g. MSWin64?
I have only ever checked myself: $^O =3D~ /^MSWin/;
Marc
------------------------------
Date: Thu, 14 Jul 2011 12:39:40 +0100
From: Justin C <justin.1104@purestblue.com>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <s413f8-n2j.ln1@zem.masonsmusic.co.uk>
On 2011-07-13, Uri Guttman <uri@StemSystems.com> wrote:
>
> you need to learn basic perl at least if you are going to do this
> project. go to learn.perl.org and read the free beginning perl book
> there. also there are a bunch of very good perl tutorial documents to
> read. perldoc.perl.org has them all if you like reading on the web.
Do you know if it's possible to get access to this without having to set
up an account with Google?
Justin.
--
Justin C, by the sea.
------------------------------
Date: Thu, 14 Jul 2011 08:42:26 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <87k4blt1vh.fsf@lifelogs.com>
On Wed, 13 Jul 2011 19:00:00 -0400 "Uri Guttman" <uri@StemSystems.com> wrote:
>>>>>> "AG" == Aaron Gray <ang.usenet@gmail.com> writes:
AG> Sorry I am very new to Perl so this means nothing to me.
UG> why then did you get a project porting a perl program?
Why not? Programming Perl doesn't have to be a profession.
Ted
------------------------------
Date: Thu, 14 Jul 2011 14:46:33 +0100
From: RedGrittyBrick <RedGrittyBrick@spamweary.invalid>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <4e1ef33a$0$2944$fa0fcedb@news.zen.co.uk>
On 14/07/2011 12:39, Justin C wrote:
> On 2011-07-13, Uri Guttman<uri@StemSystems.com> wrote:
>>
>> you need to learn basic perl at least if you are going to do this
>> project. go to learn.perl.org and read the free beginning perl book
>> there. also there are a bunch of very good perl tutorial documents to
>> read. perldoc.perl.org has them all if you like reading on the web.
>
> Do you know if it's possible to get access to this without having to set
> up an account with Google?
>
I do, it is, you don't, they are web pages aren't they?
--
RGB
------------------------------
Date: Thu, 14 Jul 2011 16:04:09 +0100
From: Justin C <justin.1104@purestblue.com>
Subject: Re: How do I know I am running on Windows command line ?
Message-Id: <94d3f8-8cn.ln1@zem.masonsmusic.co.uk>
On 2011-07-14, RedGrittyBrick <RedGrittyBrick@spamweary.invalid> wrote:
> On 14/07/2011 12:39, Justin C wrote:
>> On 2011-07-13, Uri Guttman<uri@StemSystems.com> wrote:
>>>
>>> you need to learn basic perl at least if you are going to do this
>>> project. go to learn.perl.org and read the free beginning perl book
>>> there. also there are a bunch of very good perl tutorial documents to
>>> read. perldoc.perl.org has them all if you like reading on the web.
>>
>> Do you know if it's possible to get access to this without having to set
>> up an account with Google?
>>
>
> I do, it is, you don't, they are web pages aren't they?
I wasn't sure, whenever I clicked the link I got a 'Sign in or register
with Google Docs', must be something to do with my cookies. Investigated
the link and found the source. Thanks for the KUTA that made me look
harder.
Justin.
--
Justin C, by the sea.
------------------------------
Date: Thu, 14 Jul 2011 08:51:52 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: Perl hashes and structs question
Message-Id: <87fwm9t1fr.fsf@lifelogs.com>
On Fri, 8 Jul 2011 07:10:21 -0700 (PDT) ccc31807 <cartercc@gmail.com> wrote:
c> (1) Do Perl hashes of hashes serve the same purpose as structs? I
c> think they do.
c> (2) Does Perl have a data structure similar to a struct? Outside of OO
c> Perl, I don't think so.
You're confusing many, many terms and methodologies.
Objects are never just structs, even in Perl (which comes closest to
making objects a plain data structure in my experience). Almost every
language puts its own spin on objects, from the spartan Common Lisp
defstructs to the elaborate C++, Haskell, and Java systems, but they
will at least have some semblance of encapsulation, inheritance, and
polymorphism. Structs don't have those.
Hashes of hashes have too many limitations to be structs. Class::Struct
and similar approaches may work, but Moose is IMHO really the best such
system for Perl 5. You can use it as a data-only system and move to the
methods when you need them. Just don't use it if you need high
performance.
Ted
------------------------------
Date: Thu, 14 Jul 2011 11:43:58 -0700 (PDT)
From: ccc31807 <cartercc@gmail.com>
Subject: Re: Perl hashes and structs question
Message-Id: <7f877b45-b9ea-42b2-803f-5698af3117ff@e21g2000vbz.googlegroups.com>
On Jul 14, 9:51=A0am, Ted Zlatanov <t...@lifelogs.com> wrote:
> c> (1) Do Perl hashes of hashes serve the same purpose as structs? I
> c> think they do.
> c> (2) Does Perl have a data structure similar to a struct? Outside of OO
> c> Perl, I don't think so.
>
> You're confusing many, many terms and methodologies.
When I said 'purpose' I meant a data structure composed of named
members or slots. I had just written a test engine in Lisp where I use
a struct to contain the question and choices. I was thinking about how
I would convert that to Perl, and the natural idiom would (possibly)
be an array with references to anonymous hashes, the keys being
'question', 'answer', 'wrong-1', 'wrong-2', and 'wrong-3'.
If you wanted to create an abstract data type with named slots, in
Java you would create a class, in Perl an anonymous hash hash, and in
Lisp a struct, or possibly an association or property list. Is this
wrong? Is there a better way, in Java, Perl, or Lisp?
> Objects are never just structs, even in Perl (which comes closest to
> making objects a plain data structure in my experience). =A0Almost every
> language puts its own spin on objects, from the spartan Common Lisp
> defstructs to the elaborate C++, Haskell, and Java systems, but they
> will at least have some semblance of encapsulation, inheritance, and
> polymorphism. =A0Structs don't have those.
In Lisp, structs to support a form of encapsulation and inheritance.
With defgeneric and defmethod, you can have all the polymorphism you
want.
> Hashes of hashes have too many limitations to be structs.
I wouldn't know. I am a very heavy user of hashes of hashes, and have
always found it to work as it should, even when the syntax is dense.
I've made several posts in c.l.p.m, and c.l.l, where I've given
examples, and have been taken to task over the syntax, by both Lispers
and Perlistas. Once you get past the syntax (in Perl) and the use and
placement of various kinds of delimiters, hashes of hashes work just
fine.
CC.
------------------------------
Date: Thu, 14 Jul 2011 20:05:04 +0100
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Subject: Re: Perl hashes and structs question
Message-Id: <87boww1y5b.fsf@sapphire.mobileactivedefense.com>
ccc31807 <cartercc@gmail.com> writes:
> On Jul 14, 9:51 am, Ted Zlatanov <t...@lifelogs.com> wrote:
>> c> (1) Do Perl hashes of hashes serve the same purpose as structs? I
>> c> think they do.
>> c> (2) Does Perl have a data structure similar to a struct? Outside of OO
>> c> Perl, I don't think so.
>>
>> You're confusing many, many terms and methodologies.
>
> When I said 'purpose' I meant a data structure composed of named
> members or slots. I had just written a test engine in Lisp where I use
> a struct to contain the question and choices. I was thinking about how
> I would convert that to Perl, and the natural idiom would (possibly)
> be an array with references to anonymous hashes, the keys being
> 'question', 'answer', 'wrong-1', 'wrong-2', and 'wrong-3'.
The most direct mapping of a struct (which is an ordered sequence of
fields accessible by using a specific member names) to Perl would be an
array reference and a set of symbolic constants (used by a human) the
compiler will translate into a 'field offset' (used by the machine).
------------------------------
Date: Thu, 14 Jul 2011 19:14:42 -0400
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: Perl hashes and structs question
Message-Id: <87tyao315p.fsf@lifelogs.com>
On Thu, 14 Jul 2011 11:43:58 -0700 (PDT) ccc31807 <cartercc@gmail.com> wrote:
c> I had just written a test engine in Lisp where I use a struct to
c> contain the question and choices. I was thinking about how I would
c> convert that to Perl, and the natural idiom would (possibly) be an
c> array with references to anonymous hashes, the keys being 'question',
c> 'answer', 'wrong-1', 'wrong-2', and 'wrong-3'.
Probably, though I would probably do something like Rainer's suggestion
of an array with symbolically named offsets (which is very similar to
how the Common Lisp defstruct works, actually).
c> If you wanted to create an abstract data type with named slots, in
c> Java you would create a class, in Perl an anonymous hash hash, and in
c> Lisp a struct, or possibly an association or property list. Is this
c> wrong? Is there a better way, in Java, Perl, or Lisp?
No, none of those are wrong. But an abstract data type is a big
undertaking and there are many ways to do it, especially in Perl. If
you want it to be flexible, use a hash. If you want speed, use an array
as above. If you want data validation, powerful constructors,
inheritance, polymorphism, and encapsulation, use Moose.
>> Objects are never just structs, even in Perl (which comes closest to
>> making objects a plain data structure in my experience). Almost every
>> language puts its own spin on objects, from the spartan Common Lisp
>> defstructs to the elaborate C++, Haskell, and Java systems, but they
>> will at least have some semblance of encapsulation, inheritance, and
>> polymorphism. Structs don't have those.
c> In Lisp, structs to support a form of encapsulation and inheritance.
c> With defgeneric and defmethod, you can have all the polymorphism you
c> want.
My point is that it's very spartan compared to the more powerful stuff,
especially C++. I agree it can be stretched to fit a loose description
of object orientation.
>> Hashes of hashes have too many limitations to be structs.
c> I wouldn't know. I am a very heavy user of hashes of hashes, and have
c> always found it to work as it should, even when the syntax is dense.
c> I've made several posts in c.l.p.m, and c.l.l, where I've given
c> examples, and have been taken to task over the syntax, by both Lispers
c> and Perlistas. Once you get past the syntax (in Perl) and the use and
c> placement of various kinds of delimiters, hashes of hashes work just
c> fine.
Absolutely :) But sometimes they don't, so you just have to know when
and how to supplement them with other data structures.
Ted
------------------------------
Date: Thu, 14 Jul 2011 02:22:16 -0500
From: "E.D.G." <edgrsprj@ix.netcom.com>
Subject: Perl Multitasking Question
Message-Id: <qpmdndXU4bO5BIPTnZ2dnUVZ_iydnZ2d@earthlink.com>
A fairly recent ActiveState version of Perl is being used on Windows Vista
and XP PC type computers.
Perl Multitasking Questions:
1. Is it possible to have a single Perl program work on more than one task
at a time?
Or, another way of doing that would be:
2. Is it possible to have multiple separately running Perl programs share
the same data arrays (without using Perl or Windows code that is impossibly
complicated)?
Complex Perl language programs are being written (by me) for use by
science researchers around the world. The programs can involve processing
hundreds and at times even thousands of files stored on the PC hard drive.
And the programs could run much faster if they could perform multiple tasks
at the same time.
For example, one part of a program might be doing calculations
associated with some array while a second part of the program manages
various files and gets arrays loaded and organized in the computer RAM
memory so that they will be ready for processing when the first part of the
program gets to a point where it needs them for calculations.
A good percentage of our modern computers have dual or quad core
processors and tremendous amounts of RAM memory. So they can easily work on
more than one task at a time. Also, a certain amount of time is involved
with reading and writing from the computer hard drive. And if data files
could be read into RAM memory before they were actually needed then that
could probably save a lot of time.
------------------------------
Date: Thu, 14 Jul 2011 11:39:08 +0100
From: RedGrittyBrick <RedGrittyBrick@spamweary.invalid>
Subject: Re: Perl Multitasking Question
Message-Id: <4e1ec74d$0$2487$db0fefd9@news.zen.co.uk>
On 14/07/2011 08:22, E.D.G. wrote:
> A fairly recent ActiveState version of Perl is being used on Windows
> Vista and XP PC type computers.
>
> Perl Multitasking Questions:
>
> 1. Is it possible to have a single Perl program work on more than one
> task at a time?
See `perldoc -f fork` and `perldoc perlthrtut`
>
> Or, another way of doing that would be:
>
> 2. Is it possible to have multiple separately running Perl programs
> share the same data arrays (without using Perl or Windows code that is
> impossibly complicated)?
Not easily.
Using a transactional database management system (DBMS) is one
well-established way to share data between programs.
Maybe this sort of article will be of interest:
http://t-a-w.blogspot.com/2006/10/why-perl-is-great-language-for.html
"Perl (since 5.6.0) uses theading model that is quite different from
most other languages. Each thread runs as a separate virtual machine,
and only data that is explicitly marked as shared can be shared. It also
has syntax-based locks and a few other unusual ideas. The real reason it
was done this way was retrofitting threading on fundamentally
unthreadable interpretter. That's the real rationale behind Perl OO too.
Of course it sucks for some things, but for some problems it happens to
work very nicely.
The design I used was very simple - one master thread, and a group of
worker threads. Master would keep pushing tasks on @work_todo, and
threads would pop items from it and push result to @work_done. When
master doesn't have anything else to do, it sets $finished to true and
waits for workers to finish."
--
RGB
------------------------------
Date: Thu, 14 Jul 2011 13:00:10 -0400
From: Ralph Malph <ralph@happydays.com>
Subject: Pod::Parser vs Pod::Simple
Message-Id: <356fe$4e1f20a5$ce534406$6512@news.eurofeeds.com>
Why would one prefer to use Pod::Parser vs Pod::Simple?
They seem to do essentially the same thing but there seems to be momentum
behind Pod::Simple. Why? To me Pod::Parser seems a bit well, simpler,
than Pod::Simple.
Does anyone here know the motivation behind Pod::Simple and why the core
formatters
are being migrated to Pod::Simple?
------------------------------
Date: Fri, 15 Jul 2011 02:17:16 -0500
From: tadmc@seesig.invalid
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
Message-Id: <Vq2dnffeKcPhdILTnZ2dnUVZ5tCdnZ2d@giganews.com>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
intended to be used for discussion of Perl related issues (except job
postings), whether it be comments or questions.
As you would expect, clpmisc discussions are usually very technical in
nature and there are conventions for conduct in technical newsgroups
going somewhat beyond those in non-technical newsgroups.
The article at:
http://www.catb.org/~esr/faqs/smart-questions.html
describes how to get answers from technical people in general.
This article describes things that you should, and should not, do to
increase your chances of getting an answer to your Perl question. It is
available in POD, HTML and plain text formats at:
http://www.rehabitation.com/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 that they do
know and are being the "bad kind" of Lazy.
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
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We're not bossing you around; we're making the point without
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Do *NOT* send email to the maintainer of these guidelines. It will be
discarded unread. The guidelines belong to the newsgroup so all
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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_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 and many others on the comp.lang.perl.misc newsgroup.
--
Tad McClellan
email: perl -le "print scalar reverse qq/moc.liamg\100cm.j.dat/"
The above message is a Usenet post.
I don't recall having given anyone permission to use it on a Web site.
------------------------------
Date: Thu, 14 Jul 2011 01:05:38 -0700 (PDT)
From: Marc Girod <marc.girod@gmail.com>
Subject: Re: remove undefined values witout warnings
Message-Id: <0ad06151-3fdb-4f63-a937-ea763ba79fed@y24g2000yqb.googlegroups.com>
On Jul 14, 1:01=A0am, "jl_p...@hotmail.com" <jl_p...@hotmail.com> wrote:
> =A0 =A0Nice, but I'd simplify the regular expression just a bit more:
>
> =A0 =A0 =A0 @array =3D grep { defined and m/\S/ } @array;
and even a bit more:
@array =3D grep { $_ and /\S/ } @array;
Marc
------------------------------
Date: Thu, 14 Jul 2011 08:40:38 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: remove undefined values witout warnings
Message-Id: <87oc0xt1yh.fsf@lifelogs.com>
On Sun, 10 Jul 2011 19:42:50 +0300 George Mpouras <nospam.gravitalsun@hotmail.com.nospam> wrote:
GM> I assume you did not test your proposition !
On Sun, 10 Jul 2011 19:43:21 +0300 George Mpouras <nospam.gravitalsun@hotmail.com.nospam> wrote:
GM> do not work
On Sun, 10 Jul 2011 19:52:19 +0300 George Mpouras <nospam.gravitalsun@hotmail.com.nospam> wrote:
GM> sorry, is working !
I love it. The three stages of online assistance.
I say this without sarcasm: I've done this too :)
Ted
------------------------------
Date: Thu, 14 Jul 2011 08:23:13 -0700 (PDT)
From: "jl_post@hotmail.com" <jl_post@hotmail.com>
Subject: Re: remove undefined values witout warnings
Message-Id: <735c928a-c48c-41f9-9cc4-6bc0ac632cc1@p14g2000yqj.googlegroups.com>
> On Jul 14, 1:01=A0am, "jl_p...@hotmail.com" <jl_p...@hotmail.com> wrote:
>
> > =A0 =A0Nice, but I'd simplify the regular expression just a bit more:
>
> > =A0 =A0 =A0 @array =3D grep { defined and m/\S/ } @array;
On Jul 14, 2:05=A0am, Marc Girod <marc.gi...@gmail.com> wrote:
>
> and even a bit more:
>
> =A0 =A0 @array =3D grep { $_ and /\S/ } @array;
That'll work if you want to filter out "0". But if you want to
keep "0", you'll have to use defined($_) in place of $_.
-- Jean-Luc
------------------------------
Date: Thu, 14 Jul 2011 08:24:37 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: test two hash(refs) for equality
Message-Id: <87sjq9t2p6.fsf@lifelogs.com>
On Fri, 08 Jul 2011 22:27:43 +0100 Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
RW> "Uri Guttman" <uri@StemSystems.com> writes:
>> regardless of your views, i say this for others, don't use $a and $b in
>> your code, lexically or otherwise. it is a CONVENTION that all decent
>> perl hackers are expected to do.
RW> This is now actually a circular: Decent perl programmers
RW> don't use variables named $a and $b because nobody who does is a
RW> decent perl programmer.
$a and $b are dangerous because they overlap with the sort built-ins $a
and $b. They will work most of the time and then one day you'll have to
hunt down a bug because of them that will waste more time than you could
possibly have saved by using $x and $y or whatever. If you're willing
to accept that risk, you can use them. But don't write code in a public
forum without commenting on the risk: anyone that uses your code will
unwittingly take that risk too.
The specific bugs that may come up are pretty unlikely. But since
you're writing a generic function and not a special-purpose one, you
have to be extra careful.
That is not to say that $a and $b are bad variable names. This is a
conflict between Perl's "don't worry about it" scoping facilities and
some syntactic sugar that has turned sour. But nevertheless we have to
beware using $a and $b for practical reasons, not to claim a "decent
programmer" title.
Ted
------------------------------
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:
To submit articles to comp.lang.perl.announce, send your article to
clpa@perl.com.
Back issues are available via anonymous ftp from
ftp://cil-www.oce.orst.edu/pub/perl/old-digests.
#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 V11 Issue 3444
***************************************
