[32237] in Perl-Users-Digest
Perl-Users Digest, Issue: 3502 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Sep 20 06:09:23 2011
Date: Tue, 20 Sep 2011 03:09:07 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Tue, 20 Sep 2011 Volume: 11 Number: 3502
Today's topics:
Re: $_ or @_ in subrountine? <rweikusat@mssgmbh.com>
Re: $_ or @_ in subrountine? <rweikusat@mssgmbh.com>
Can't rename or move files <Joey@still_Learning.invalid>
Re: Can't rename or move files <tadmc@seesig.invalid>
Re: Catalyst Newsgroup? <stevem_@nogood.com>
Re: Catalyst Newsgroup? <tadmc@seesig.invalid>
Re: Catalyst Newsgroup? <stevem_@nogood.com>
Date Manip Improvements ikinal@att.net
Re: Date Manip Improvements <glex_no-spam@qwest-spam-no.invalid>
metacpan.org <dilbert1999@gmail.com>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@seesig.invalid
Re: Question about range of Lines <dba1_no_spam@csi.it>
Re: Question about range of Lines sln@netherlands.com
Re: Question about range of Lines sln@netherlands.com
Re: Question about range of Lines <ben.usenet@bsb.me.uk>
Re: Question about range of Lines sln@netherlands.com
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Sun, 18 Sep 2011 20:39:26 +0100
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Subject: Re: $_ or @_ in subrountine?
Message-Id: <87r53d63o1.fsf@sapphire.mobileactivedefense.com>
Tad McClellan <tadmc@seesig.invalid> writes:
> Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
>> Jürgen Exner <jurgenex@hotmail.com> writes:
>>> "ela" <ela@yantai.org> wrote:
>>>>I pass a long file name to a subrountine by:
>>>>
>>>>my ($file1, $file2, $file3) = @ARGV;
>>>>
>>>>&mysub($file1);
>>>
>>> Why are you overriding the prototype of mysub() when you are not even
>>> declaring a prototype for mysub()? That doesn't make any sense.
>>>
>>>>sub mysub {
>>>> my $subfile1 = $_; #this doesn't work, $subfile1 remains to be ""
>>>
>>> Really? That surprises me. I would have assumed it remained undef.
>>
>> $_ is a 'special global variable' and this means that the assignment
>> quoted above will assign the present value of $_ to $subfile.
>
>
> So far, so good.
>
>
>> And this
>> can pretty much be anything,
>
> No, it must be undef in the program that is being discussed in this
> thread.
Maybe, maybe not. There was no context hinting at that in the posting
I replied to and
>> since $_ is used as 'default variable' in
>> various constructs, such as
>>
>> for (@a) { ... }
>>
>> while (<>) { ... }
>>
>> given ($blah) {
>> when (/something) {
>> }
>> }
it is a special case in this respect: The strict module will not bark
at it. Yet accidental use of it may yield anything, depending on
whatever the context of the use happened to be. And I doubt that the
OP was aware of that since he used it in a place where $_[0] should
have been used instead. Hence, it seemed worth mentioning its special
properties.
------------------------------
Date: Sun, 18 Sep 2011 20:40:35 +0100
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Subject: Re: $_ or @_ in subrountine?
Message-Id: <87mxe163m4.fsf@sapphire.mobileactivedefense.com>
Jürgen Exner <jurgenex@hotmail.com> writes:
> Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
>>Jürgen Exner <jurgenex@hotmail.com> writes:
>>> "ela" <ela@yantai.org> wrote:
[...]
>>>>sub mysub {
>>>> my $subfile1 = $_; #this doesn't work, $subfile1 remains to be ""
>>>
>>> Really? That surprises me. I would have assumed it remained undef.
[...]
>> undefined values still stringify to empty strings. No matter how
>>ideological impure this may seem to whomever.
>
> Sure. But the OP explicitely said the value was the empty string, he
> didn't talk about the stringified value.
The Perl documentation calls this 'an undefined empty string' in
various places. I quoted a couple of them not that long ago.
------------------------------
Date: Mon, 19 Sep 2011 14:25:21 -0700
From: "Joey@still_Learning.invalid" <Joey@still_Learning.invalid>
Subject: Can't rename or move files
Message-Id: <gqbf77d3l1cc8n2vm2i8q5lrf3qoc2g1hn@4ax.com>
I'm using MIME::Parser and FILE::Copy modules to parse an uploaded
multi-part file and move the parsed files to a new folder on my server, as
follows:
Select multiple files and send to Perl script. Perl creates a folder ("A")
on the server and uploads the multi-part package to folderA. MIME::Parser
decodes the package and places the parsed files in the folderA. The file
names are changed and the renamed files are moved to another folder ("B"),
and folderA that was created, now empty, is deleted. Code follows:
chdir $filePathNew or die "Can't change dir: $!";
my $i=0;
opendir DH,$filePathNew or die "Can't opendir $filePathNew $!";
foreach $file (readdir(DH)) {
if (length($file gt 4)) {
$indx = index($file,'.');
$lngth = length($file);
$extLength = $lngth - ($indx + 1);
$fileXt = substr($file,$indx+1,$extLength);
$makeExt = $i.'.'.$fileXt;
$newFileName = $imgCode.$makeExt;
rename($file,$newFileName) or die "Could not rename file: $!";
move($newFileName, "$filePath/$newFileName") or die "File cannot be
moved.";
$i++;
}
}
#delete new unique upload folder
rmdir $filePathNew or die "Can't remove $filePathNew $!";
Filenames change and moves to folderB don't work when the original
filenames are of the form:
2011-09-15 Doe, John - Right Side.ext
It works properly if the filenames are of the form:
Doe, John - Right Side.ext
I am not receiving error messages informing me the names couldn't be
changed or that the files can't be moved. I am receiving an error message
telling me the created folderA can't be deleted, because the folder isn't
empty.
Does anyone know what the problem/solution might be?
TIA,
--
Joey
------------------------------
Date: Mon, 19 Sep 2011 16:35:45 -0500
From: Tad McClellan <tadmc@seesig.invalid>
Subject: Re: Can't rename or move files
Message-Id: <slrnj7fcl7.bic.tadmc@tadbox.sbcglobal.net>
Joey@still_Learning.invalid <Joey@still_Learning.invalid> wrote:
> if (length($file gt 4)) {
You have managed to cram 2 errors into one line there.
Look carefully. What are you taking the length() of?
You are taking the length of
$file gt 4
If that comparison is true, then the length is one,
if false then the length is zero.
Secondly, you use gt to compare strings.
You use > to compare numbers.
if (length($file) > 4) {
--
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: Sun, 18 Sep 2011 09:47:16 -0700
From: Steve May <stevem_@nogood.com>
Subject: Re: Catalyst Newsgroup?
Message-Id: <0ipdq.2304$CY4.1354@newsfe04.iad>
On 09/17/2011 11:56 AM, Tad McClellan wrote:
> Steve May<stevem_@nogood.com> wrote:
>
>> I've been looking around for a news group
>
>
> There is no newsgroup specific to Catalyst.
>
>
>> or list that focuses on
>> Catalyst and don't seem to be having any luck.
>
>> Pointers/links appreciated.
>
>
> When you are wondering about Perl-related mailing list,
> your first stop should be the list of over 200 at:
>
> http://lists.perl.org
>
> This one looks promising:
>
> http://lists.perl.org/list/catalyst.html
>
>
Thanks Tad, didn't know about lists.perl.org.
The catalyst archives look interesting, I'll spend some time with them.
Steve
------------------------------
Date: Sun, 18 Sep 2011 13:58:33 -0500
From: Tad McClellan <tadmc@seesig.invalid>
Subject: Re: Catalyst Newsgroup?
Message-Id: <slrnj7cf2o.7fu.tadmc@tadbox.sbcglobal.net>
Steve May <stevem_@nogood.com> wrote:
> Thanks Tad, didn't know about lists.perl.org.
perldoc -q mail
or
perldoc -q lists
What mailing lists are there for Perl?
The Perl FAQ is a wonderful thing, but only if it is consulted. :-)
--
Tad McClellan
email: perl -le "print scalar reverse qq/moc.liamg\100cm.j.dat/"
The above message is a Usenet post.
I don't recall having given anyone permission to use it on a Web site.
------------------------------
Date: Mon, 19 Sep 2011 12:41:08 -0700
From: Steve May <stevem_@nogood.com>
Subject: Re: Catalyst Newsgroup?
Message-Id: <3XMdq.3063$CY4.643@newsfe04.iad>
On 09/18/2011 11:58 AM, Tad McClellan wrote:
>
> The Perl FAQ is a wonderful thing, but only if it is consulted. :-)
>
>
I think I had that covered in my original post:
>>>> Perhaps I'm just exceptionally thick today, but....
:-)
\s
------------------------------
Date: Mon, 19 Sep 2011 14:12:01 -0700 (PDT)
From: ikinal@att.net
Subject: Date Manip Improvements
Message-Id: <629ac6a3-b14c-47fe-ac27-cbe280e1e497@j1g2000yqn.googlegroups.com>
I've profiled our input of large database files that are spending
large amounts of
time using Date::Manip
functions such as ParseDateString and UnixDate.
[using the NYTProfile, a very nice tool!!!]
While in some cases, the data is repetitive, so at first glance, I
thought
memiozation might help
BUT In many cases, the data is different [it might be the seconds
value that
advances, etc], so there's still a big hit...
Looking at the code, it's pretty complex, so converting it to C code
and inlining seems a stretch...
Does anyone have any suggestions?
Thanks,
Ihor Kinal
------------------------------
Date: Mon, 19 Sep 2011 21:35:20 +0000
From: "J. Gleixner" <glex_no-spam@qwest-spam-no.invalid>
Subject: Re: Date Manip Improvements
Message-Id: <4e77b598$0$63189$815e3792@news.qwest.net>
On 09/19/11 21:12, ikinal@att.net wrote:
> I've profiled our input of large database files that are spending
> large amounts of
> time using Date::Manip
> functions such as ParseDateString and UnixDate.
> [using the NYTProfile, a very nice tool!!!]
>
> While in some cases, the data is repetitive, so at first glance, I
> thought memiozation might help
>
> BUT In many cases, the data is different [it might be the seconds
> value that advances, etc], so there's still a big hit...
>
> Looking at the code, it's pretty complex, so converting it to C code
> and inlining seems a stretch...
>
> Does anyone have any suggestions?
Look near the end of the documentation for 'SHOULD I USE DATE::MANIP'.
In short, there are other modules which might be faster.
If the manipulation is always doing the same thing, e.g. converting
201101022359 to 01/02/2011 23:59, then doing it yourself may be
faster than a generalized method that accepts many different formats.
------------------------------
Date: Mon, 19 Sep 2011 07:28:08 -0700 (PDT)
From: Dilbert <dilbert1999@gmail.com>
Subject: metacpan.org
Message-Id: <bd6fa3ec-f946-4a89-b856-971f06c36ca9@w28g2000yqw.googlegroups.com>
I used to use http://search.cpan.org/ to browse the CPAN Directory.
But now I stumbled upon https://metacpan.org/ which has a Google look
and feel. I prefer https://metacpan.org/ over http://search.cpan.org/.
What do you think ?
------------------------------
Date: Tue, 20 Sep 2011 02:23:04 -0500
From: tadmc@seesig.invalid
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
Message-Id: <8NOdnc6JaunFouXTnZ2dnUVZ5uidnZ2d@giganews.com>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($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
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_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: Mon, 19 Sep 2011 11:08:46 +0200
From: Mauro <dba1_no_spam@csi.it>
Subject: Re: Question about range of Lines
Message-Id: <j570qv$bal$1@mophus.csi.it>
> Another solution which avoids the range operator:
>
> perl -e '$/ = undef; $s =<>; print $s =~ /^(Tuesday.*?)^Friday/sm;' t1
>
> hp
>
Thank you, it is a nice idea ( but for too much long files, perhaps ).
Regards
Mauro
------------------------------
Date: Mon, 19 Sep 2011 12:39:29 -0700
From: sln@netherlands.com
Subject: Re: Question about range of Lines
Message-Id: <le5f779pesmcgq7qlbaf3j0vstvg6aijs6@4ax.com>
On Mon, 19 Sep 2011 11:08:46 +0200, Mauro <dba1_no_spam@csi.it> wrote:
>> Another solution which avoids the range operator:
>>
>> perl -e '$/ = undef; $s =<>; print $s =~ /^(Tuesday.*?)^Friday/sm;' t1
>>
>> hp
>>
>
>Thank you, it is a nice idea ( but for too much long files, perhaps ).
>
"but for too much long files, perhaps"
I would give this credibility if you can show some code that
guarantees there is a 'Friday'.
while (<>) {
if (/Tuesday/ .. /Friday/) {}
}
In this case, the operator .. flips true on $_=~/Tuesday/ and remains
so until after it finds $_=~/Friday/ or, until the while() is false.
I can see why you would be interested in how the range operator
works in this case, but don't promote it to something perfect.
-sln
------------------------------
Date: Mon, 19 Sep 2011 13:05:54 -0700
From: sln@netherlands.com
Subject: Re: Question about range of Lines
Message-Id: <s27f77hmgpj5nvqt4to7c7869ics102ev4@4ax.com>
On Thu, 15 Sep 2011 09:28:42 +0200, mauro papandrea <dba1@csi.it> wrote:
>Given this simple file:
>
>cat t1
>
>Sunday
>Monday
>Tuesday
>Wednesday
>Thursday
>Friday
>Saturday
>
>with
>
>perl -ne 'print if /Tuesday/ .. /Friday/;' t1
>
>I can get:
>
>Tuesday
>Wednesday
>Thursday
>Friday
>
>
>Is there a simple way to modify the range selection in order to get all
>the lines but the last in the range?
>Namely, getting this output:
>
>Tuesday
>Wednesday
>Thursday
>
>An idea could be to push back last line but I do not know how to do that.
>
>Thank you
>
>Regards
>
>Mauro
>
>PS this is an oversimplified case for the sake of simplicity
As others mentioned, I would go the simple way using an range operator
and an additional regex:
print if (/Tuesday/ .. /Friday/ and !/Tuesday); # not Tuesday
print if (/Tuesday/ .. /Friday/ and !/Tuesday|Friday/); # not Tuesday nor Friday
print if (/Tuesday/ .. /Friday/ and !/Friday/); # not Friday
If you want to use just a range operator, it becomes difficult (untested):
# not Tuesday
perl -ne 'print if $st=~/Tuesday/ .. /Friday/; $st=$_' t1
# not Tuesday nor Friday
(left as an exersize)
# not Friday
perl -e 'do {print if /Tuesday/ .. $st=~/Friday/; $_=$st;} while ($st=<>)' t1
-sln
------------------------------
Date: Mon, 19 Sep 2011 23:02:18 +0100
From: Ben Bacarisse <ben.usenet@bsb.me.uk>
Subject: Re: Question about range of Lines
Message-Id: <0.c722d956ab7ead829cf4.20110919230218BST.87d3ewtclx.fsf@bsb.me.uk>
sln@netherlands.com writes:
> On Thu, 15 Sep 2011 09:28:42 +0200, mauro papandrea <dba1@csi.it> wrote:
<snip>
>>Is there a simple way to modify the range selection in order to get all
>>the lines but the last in the range?
>>Namely, getting this output:
>>
>>Tuesday
>>Wednesday
>>Thursday
<snip>
>>PS this is an oversimplified case for the sake of simplicity
>
> As others mentioned, I would go the simple way using an range operator
> and an additional regex:
>
> print if (/Tuesday/ .. /Friday/ and !/Tuesday); # not Tuesday
> print if (/Tuesday/ .. /Friday/ and !/Tuesday|Friday/); # not Tuesday nor Friday
I think the days of the week, all in order, were just an example. If
so, then these two are not quite what they seem because they exclude
extra Tuesdays. Of course, it's possible that the string that starts
the range never appears in it (in which case all is well) but the
example may have been oversimplified.
> print if (/Tuesday/ .. /Friday/ and !/Friday/); # not Friday
There's no problem here because the end pattern can't appear in the
range -- by definition. And since this is what the OP asked for, a rang
and regex does seem like the way to go.
<snip>
--
Ben.
------------------------------
Date: Mon, 19 Sep 2011 17:21:23 -0700
From: sln@netherlands.com
Subject: Re: Question about range of Lines
Message-Id: <dslf775fjv1s1p7t9mjspmm54vollrtnii@4ax.com>
On Mon, 19 Sep 2011 23:02:18 +0100, Ben Bacarisse <ben.usenet@bsb.me.uk> wrote:
>sln@netherlands.com writes:
>
>> On Thu, 15 Sep 2011 09:28:42 +0200, mauro papandrea <dba1@csi.it> wrote:
><snip>
>>>Is there a simple way to modify the range selection in order to get all
>>>the lines but the last in the range?
>>>Namely, getting this output:
>>>
>>>Tuesday
>>>Wednesday
>>>Thursday
><snip>
>>>PS this is an oversimplified case for the sake of simplicity
>>
>> As others mentioned, I would go the simple way using an range operator
>> and an additional regex:
>>
>> print if (/Tuesday/ .. /Friday/ and !/Tuesday); # not Tuesday
>> print if (/Tuesday/ .. /Friday/ and !/Tuesday|Friday/); # not Tuesday nor Friday
>
>I think the days of the week, all in order, were just an example. If
>so, then these two are not quite what they seem because they exclude
>extra Tuesdays. Of course, it's possible that the string that starts
>the range never appears in it (in which case all is well) but the
>example may have been oversimplified.
I believe this is a true statement.
>> print if (/Tuesday/ .. /Friday/ and !/Friday/); # not Friday
>
>There's no problem here because the end pattern can't appear in the
>range -- by definition. And since this is what the OP asked for, a rang
>and regex does seem like the way to go.
>
And this is true too. But, I believe using the range operator in this
context does not imply a 'Friday' exists in the data, where 'Tuesday'
must if the condition is satisfied. Thats not saying anything is wrong
using the range operator like this, just that some extra buffering
might/might-not be needed. There is usually more to posters questions
than an academic translation.
-sln
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