[32156] in Perl-Users-Digest
Perl-Users Digest, Issue: 3421 Volume: 11
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Tue Jun 21 11:09:25 2011
Date: Tue, 21 Jun 2011 08:09:03 -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, 21 Jun 2011 Volume: 11 Number: 3421
Today's topics:
Re: [RegEx] Optional parameter <tzz@lifelogs.com>
Re: [RegEx] Optional parameter <rweikusat@mssgmbh.com>
Benchmark module with some more statistics <peter@makholm.net>
Re: FAQ 2.6 What modules and extensions are available f <brian.d.foy@gmail.com>
Perl definition of newline? <rop049@gmail.com>
Re: Perl definition of newline? <willem@toad.stack.nl>
Re: Perl definition of newline? <jurgenex@hotmail.com>
Re: Perl definition of newline? <rweikusat@mssgmbh.com>
Re: Perl definition of newline? <tadmc@seesig.invalid>
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@seesig.invalid
reading a binary file <rahul_vasishta@yahoo.co.in>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Tue, 21 Jun 2011 07:51:18 -0500
From: Ted Zlatanov <tzz@lifelogs.com>
Subject: Re: [RegEx] Optional parameter
Message-Id: <87r56ns5yx.fsf@lifelogs.com>
On Mon, 20 Jun 2011 14:31:45 +0100 Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
RW> Ted Zlatanov <tzz@lifelogs.com> writes:
>> I'd rather use warnings religiously than suffer in maintenance hell.
>> You may feel differently, but debugging code without warnings
>> (especially when all you have are the log files) is a nightmare. Simple
>> typos can turn into multi-hour hunts,
RW> Can you provide an example of a 'simple typo' perl cannot detect at
RW> compile time but does detect at runtime?
% perl -w -e '$h{myentry} = 1; print $h{myenty};'
Use of uninitialized value in print at -e line 1.
% perl -e '$h{myentry} = 1; print $h{myenty};'
(no output)
Ted
------------------------------
Date: Tue, 21 Jun 2011 14:06:43 +0100
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Subject: Re: [RegEx] Optional parameter
Message-Id: <87hb7j9vvg.fsf@sapphire.mobileactivedefense.com>
Ted Zlatanov <tzz@lifelogs.com> writes:
> On Mon, 20 Jun 2011 14:31:45 +0100 Rainer Weikusat <rweikusat@mssgmbh.com> wrote:
> RW> Ted Zlatanov <tzz@lifelogs.com> writes:
>>> I'd rather use warnings religiously than suffer in maintenance hell.
>>> You may feel differently, but debugging code without warnings
>>> (especially when all you have are the log files) is a nightmare. Simple
>>> typos can turn into multi-hour hunts,
>
> RW> Can you provide an example of a 'simple typo' perl cannot detect at
> RW> compile time but does detect at runtime?
>
> % perl -w -e '$h{myentry} = 1; print $h{myenty};'
> Use of uninitialized value in print at -e line 1.
That's not quite an example of 'a simple typo' but another attempt at
inventing a contrived example demonstrating the Very High
Usefulness Of Not Knowing What An Uninitialized Value Happens To
Be[tm] (namely, the 'indeterminate' and - in practice - more or less
random value a non-initialized object with 'automatic storage
duration' happens to have in C).
How have you managed to escape the maintenance hell of Perl not being
able to detect simply typos like this:
$c = $a - $b # should have been +
or
$c = $a - $b # should have been $b - $a
?
NB: I'm genuinely interested in something useful 'Perl runtime
warnings' provide. But I've already ruled out 'Oh my GAWD it is
UNDEF !!!1!!!'. That's not useful to me. YMMV.
------------------------------
Date: Tue, 21 Jun 2011 14:09:15 +0200
From: Peter Makholm <peter@makholm.net>
Subject: Benchmark module with some more statistics
Message-Id: <878vsv5qtw.fsf@vps1.hacking.dk>
In some cases just getting the average runtime from a benchmark isn't
really informative. Unfortunately this is all that we get from
Benchmark.pm
I have created a module giving a bit more information, currently
available on github:
https://github.com/pmakholm/benchmark-statistics-perl
Basically it just runs some code a couple of times and feeds the data to
Shlomi Fish's Statistics::Descriptive with the posibility of printing
some basic statistics. The API should be "not quite unlike" Benchmark.pm
but the output quite different.
Would this be of general interest (i.e. should I enhance it and push it
to CPAN?)
I'm no statistics expert so I'm also a bit worried I'm sticking my hand
in a hornets nest requiring me to defending soem shoole of creating
benchmarks.
I think it is to orthogonal from the data repported by Benchmark.pm to
be included in there?
And finally, it's almost all too simple. But having something simple on
CPAN might provoke someone knowledge into making something more usefull?
//Makholm
------------------------------
Date: Tue, 21 Jun 2011 13:57:15 +0200
From: brian d foy <brian.d.foy@gmail.com>
Subject: Re: FAQ 2.6 What modules and extensions are available for Perl? What is CPAN? What does CPAN/src/... mean?
Message-Id: <210620111357157058%brian.d.foy@gmail.com>
In article <184bd$4dff96a9$ce534406$18874@news.eurofeeds.com>, Ralph
Malph <ralph@happydays.com> wrote:
> What does the perl 5 porters faq have to do with the perlfaq
> (http://faq.perl.org/) ?
> The link you posted is useless and provides no answer to any question
> raised in this thread.
The perlfaq documents are part of the perl source repository. To make a
change, that's where you have to send the patches. I said to send a
patch to perl5-porters, which is the mailing list where the perl
committers hang out and will see your change. I didn't say anything
about the p5p faq.
------------------------------
Date: Tue, 21 Jun 2011 01:27:22 -0700 (PDT)
From: rop rop <rop049@gmail.com>
Subject: Perl definition of newline?
Message-Id: <2adcca8f-46a2-47b9-be0e-fc9f723eccab@b3g2000vbm.googlegroups.com>
Hi,
For portability reasons, I would just like to know what is the exact
definition of "\n" in perl?
It says in Perl documentation that it is the "newline" character.
Does this mean it is always the ascii-code 0A (and nothing else) on
all platforms and OS:es?
Or could it ever be something other than that?
I believe, in other languages, "\n" may for example expand to 0D+0A on
windows-platform, but never in perl?
------------------------------
Date: Tue, 21 Jun 2011 08:40:00 +0000 (UTC)
From: Willem <willem@toad.stack.nl>
Subject: Re: Perl definition of newline?
Message-Id: <slrnj00m70.b9k.willem@toad.stack.nl>
rop rop wrote:
) Hi,
)
) For portability reasons, I would just like to know what is the exact
) definition of "\n" in perl?
)
) It says in Perl documentation that it is the "newline" character.
)
) Does this mean it is always the ascii-code 0A (and nothing else) on
) all platforms and OS:es?
Yes. Or perhaps some other newline-character, but always single.
But read below.
) Or could it ever be something other than that?
No, but read below.
) I believe, in other languages, "\n" may for example expand to 0D+0A on
) windows-platform, but never in perl?
You believe wrongly.
In other languages it is also ascii-code 0x0A (or some other code).
However, and this applies to Perl as well:
When you output a 0x0A to a 'text' stream, it may get translated to the
OS's native line separator, such as CRLF.
So, as soon as you write to a file (or stdout), the translation occurs.
But only then.
Be sure to check the perldoc for 'binmode'.
SaSW, Willem
--
Disclaimer: I am in no way responsible for any of the statements
made in the above text. For all I know I might be
drugged or something..
No I'm not paranoid. You all think I'm paranoid, don't you !
#EOT
------------------------------
Date: Tue, 21 Jun 2011 03:21:16 -0700
From: Jürgen Exner <jurgenex@hotmail.com>
Subject: Re: Perl definition of newline?
Message-Id: <lvr007pcov6sbo1uf5djfrbnimu8bssk11@4ax.com>
rop rop <rop049@gmail.com> wrote:
>For portability reasons, I would just like to know what is the exact
>definition of "\n" in perl?
>
>It says in Perl documentation that it is the "newline" character.
>
>Does this mean it is always the ascii-code 0A (and nothing else) on
>all platforms and OS:es?
No.
>Or could it ever be something other than that?
It most certainly will be something else on a platform that doesn't use
ASCII but e.g. EBCDIC or some other encoding.
>I believe, in other languages, "\n" may for example expand to 0D+0A on
>windows-platform, but never in perl?
When written to a text stream it will always be expanded to whatever is
the proper combination for that platform.
jue
------------------------------
Date: Tue, 21 Jun 2011 12:02:51 +0100
From: Rainer Weikusat <rweikusat@mssgmbh.com>
Subject: Re: Perl definition of newline?
Message-Id: <87liwva1lw.fsf@sapphire.mobileactivedefense.com>
rop rop <rop049@gmail.com> writes:
> For portability reasons, I would just like to know what is the exact
> definition of "\n" in perl?
>
> It says in Perl documentation that it is the "newline" character.
This is the exact definition. As soon as things go beyond Perl, what
exactly constitutes 'a text file' depends on the platform. The three
conventions I'm aware of are
- lines separated by ASCII NL (0xa), UNIX(*), Linux
- lines separated by ASCII CR (0xd), MAC
- lines separated by ASCII CR + ASCII NL WinDOS
But that's supposed to be handled transparently by the responsible I/O
code, meaning, whatever the platform happens to use becomes \n inside
Perl and a Perl \n becomes whatever the platform happens to use as
soon as it moves outside of Perl.
------------------------------
Date: Tue, 21 Jun 2011 07:45:51 -0500
From: Tad McClellan <tadmc@seesig.invalid>
Subject: Re: Perl definition of newline?
Message-Id: <slrnj0147a.3ul.tadmc@tadbox.sbcglobal.net>
rop rop <rop049@gmail.com> wrote:
> For portability reasons,
^^^^
^^^^
You should have probably asked yourself:
Are there docs about the portability of perl?
...
> I would just like to know what is the exact
> definition of "\n" in perl?
There is a section named "Newlines" in:
perldoc perlport
the first 2 paragraphs do a pretty good job:
=head2 Newlines
In most operating systems, lines in files are terminated by newlines.
Just what is used as a newline may vary from OS to OS. Unix
traditionally uses C<\012>, one type of DOSish I/O uses C<\015\012>,
and S<Mac OS> uses C<\015>.
Perl uses C<\n> to represent the "logical" newline, where what is
logical may depend on the platform in use. In MacPerl, C<\n> always
means C<\015>. In DOSish perls, C<\n> usually means C<\012>, but
when accessing a file in "text" mode, STDIO translates it to (or
from) C<\015\012>, depending on whether you're reading or writing.
Unix does the same thing on ttys in canonical mode. C<\015\012>
is commonly referred to as CRLF.
> It says in Perl documentation that it is the "newline" character.
It would have been very helpful to us if you had shared exactly
where you are referring to there.
I'd guess:
The following escape sequences are available in constructs that
interpolate and in transliterations.
...
\n newline (NL)
in the "Quote and Quote-like Operators" section of perlop?
> Does this mean it is always the ascii-code 0A (and nothing else) on
> all platforms and OS:es?
It means that within your Perl code \n always represents the
"end of a line"...
> Or could it ever be something other than that?
It is when you do _input_ or _output_ that this "end of a line" marker
is translated into with whatever is appropriate for the "platform"
(OS, filesystem,...).
What is an "appropriate" translation is summarized a bit
further down in the perlport doc:
Some of this may be confusing. Here's a handy reference to the ASCII CR
and LF characters. You can print it out and stick it in your wallet.
LF eq \012 eq \x0A eq \cJ eq chr(10) eq ASCII 10
CR eq \015 eq \x0D eq \cM eq chr(13) eq ASCII 13
| Unix | DOS | Mac |
---------------------------
\n | LF | LF | CR |
\r | CR | CR | LF |
\n * | LF | CRLF | CR |
\r * | CR | CR | LF |
---------------------------
* text-mode STDIO
> I believe, in other languages,
This isn't really a question of which language, it is a
question of a language's input/output mechanisms.
> "\n" may for example expand to 0D+0A on
^^^^^^^^^
> windows-platform,
Q: When would this expansion occur?
A: Upon output.
So, it appears that you already knew all of this.
:-)
> but never in perl?
That is true, because when you are doing input or output,
you are not "in perl".
--
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: Tue, 21 Jun 2011 02:16:46 -0500
From: tadmc@seesig.invalid
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
Message-Id: <Ce-dnUGo_57D2J3TnZ2dnUVZ5sqdnZ2d@giganews.com>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.9 $)
This newsgroup, commonly called clpmisc, is a technical newsgroup
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As you would expect, clpmisc discussions are usually very technical in
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The article at:
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describes how to get answers from technical people in general.
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For more information about netiquette in general, see the "Netiquette
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A note to newsgroup "regulars":
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Must
This section describes things that you *must* do before posting to
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have others do your work.
The perl distribution includes documentation that is copied to your hard
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You should either find out where the docs got installed on your system,
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Checking the FAQ before posting is required in Big 8 newsgroups in
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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
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Check the other standard Perl docs (*.pod)
The perl distribution comes with much more documentation than is
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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
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Try doing a word-search in the standard docs for some words/phrases
taken from your problem statement or from your very carefully worded
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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
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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
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Your post is in competition with 199 other posts. You need to "win"
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These sections describe how you can help keep your article from being
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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
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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
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Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
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Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
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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
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to the community with your very first post! If your choice of
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Use an effective followup style
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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
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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).
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"strict"ures (perldoc strict).
You should not bother the hundreds/thousands of readers of the
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Use copy/paste or your editor's "import" function rather than
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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.
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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: Tue, 21 Jun 2011 07:10:41 -0700 (PDT)
From: "Rahul!!" <rahul_vasishta@yahoo.co.in>
Subject: reading a binary file
Message-Id: <cc5a13df-694f-4a94-9f24-5e65ba688656@34g2000pru.googlegroups.com>
Hi all,
I am trying to store dll file uploaded by user to DB. But I am seeing
issues, dll file is getting corrupted. The size of the file inserted
is greater than original file. Can some body help me here. Posting cgi-
perl code snippet,
//WEB PAGE CODE
<form method=post ENCTYPE="multipart/form-data">
<input type=hidden name=type value="application/octet-stream">
<b>Path to file:</b><br>
<input type=file name=data id=data size=60><br><br>
<b>Description</b>:<br>
<input name=description size=60><br><br>
<input type=submit value="Submit">
</form>
#perl-cgi code,executed on Linux box
#this gives me file handle
my $daata=$cgi->upload('data');
my $fulldata;
#reading content of binary file
read($daata, $fulldata, -s $daata );
$dbh->do("insert into attachments"
. " ( file_name,file_data)"
. " values"
. "(?,?)",undef, $file_name, $fulldata);
# . "(?,?)",undef, $file_name, $dbh->BLOB_TYPE($fulldata)); this also
doesn't work
But the dll is getting corrupted. The attachments.file_data field is
of type longblob. Am I doing something wrong here? Is there any issue
with the statement that reads content of the file?
Please help me on this,
-Rahul
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
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Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V11 Issue 3421
***************************************
