[28638] in Perl-Users-Digest
Perl-Users Digest, Issue: 10002 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Fri Nov 24 09:05:54 2006
Date: Fri, 24 Nov 2006 06:05:04 -0800 (PST)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Fri, 24 Nov 2006 Volume: 10 Number: 10002
Today's topics:
Re: Compare UNIX file time with time in a variable <phynkel@gmail.com>
Re: Compare UNIX file time with time in a variable <phynkel@gmail.com>
Re: Extracting Date using Regular Expressions <benmorrow@tiscali.co.uk>
handling hanging database connections: timeout in perl daniel.crosby@gmx.de
Re: How to read the Doctype Information out of an XML F pod69@gmx.net
One texture Perl / OpenGL weer1@gmx.net
Posting Guidelines for comp.lang.perl.misc ($Revision: tadmc@augustmail.com
the opposite of 'chop' <dr.mtarver@ukonline.co.uk>
Re: the opposite of 'chop' <mritty@gmail.com>
Re: what is the best choose fork or thread? <benmorrow@tiscali.co.uk>
Re: what is the best choose fork or thread? <ynl@nsparks.net>
Re: what is the best choose fork or thread? <ynl@nsparks.net>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 24 Nov 2006 05:06:17 -0800
From: "phynkel@gmail.com" <phynkel@gmail.com>
Subject: Re: Compare UNIX file time with time in a variable
Message-Id: <1164373577.207636.235310@l12g2000cwl.googlegroups.com>
Mumia W. (reading news) wrote:
> On 11/23/2006 01:39 PM, phynkel@gmail.com wrote:
> > Application: web
> >
> > Background: The web page gets a string from the user and it's passed to
> > PERL. PERL runs a UNIX find command to find files with that string.
> > Then there's a lot of processing before the results are returned to the
> > user.
> >
> > Problem: The user wants a web page option that will allow them to set
> > the "latest" possible date of the files that can be searched.
> >
> > My idea: Get date string from user input. Use that string in a PERL
> > system command to "touch" a file with that date. Something like
> >
> > system 'touch --date $lastdate /tmp/touchfile';
> >
> > Then the PERL system command running the find will look for files
> > older than "/tmp/touchfile".
> >
> > I'm looking for a simpler and/or cleaner way to do things. Any
> > thoughts?
> >
> > I don't want to make more than one pass of the files, so I want to get
> > everything I can out of the find command as it does some other inline
> > processing before getting back to PERL
> >
> > TX
> >
>
> What have you tried so far?
>
> First, do validity checking on $lastdate before giving it to the system
> command, or you'll be sorry.
of course, but thanks
>
> Second, I'd advise using File::Find and checking against the $lastdate
> before pushing the files onto an array (in the wanted function).
2n d time this advice was mentioned - must be good -will lokk it up
after having coffee :-) tx!
>
>
> --
> paduille.4060.mumia.w@earthlink.net
------------------------------
Date: 24 Nov 2006 05:09:09 -0800
From: "phynkel@gmail.com" <phynkel@gmail.com>
Subject: Re: Compare UNIX file time with time in a variable
Message-Id: <1164373749.131312.6660@m7g2000cwm.googlegroups.com>
Sherm Pendley wrote:
> "phynkel@gmail.com" <phynkel@gmail.com> writes:
>
> > Background: The web page gets a string from the user and it's passed to
> > PERL. PERL runs a UNIX find command to find files with that string.
>
> The name of the language is Perl, not PERL.
>
> > I'm looking for a simpler and/or cleaner way to do things. Any
> > thoughts?
>
> Have a look at File::Find. Much easier to use from within a Perl script,
> and allows you to write a callback function that can use whatever criteria
> you want to filter out files you're not interested in.
>
> sherm--
>
TX - will look it up .
This little project was my intro to Perl. Originally was used in its
simplest form, now is becoming more complex and is being used by a
bunch of researchers every day.
tx for the advice.
> --
> Web Hosting by West Virginians, for West Virginians: http://wv-www.net
> Cocoa programming in Perl: http://camelbones.sourceforge.net
------------------------------
Date: Thu, 23 Nov 2006 06:05:03 +0000
From: Ben Morrow <benmorrow@tiscali.co.uk>
Subject: Re: Extracting Date using Regular Expressions
Message-Id: <f9qf34-q81.ln1@osiris.mauzo.dyndns.org>
Quoth "Kimi" <shafa.fahad@gmail.com>:
>
> Paul Lalli wrote:
> > > Kimi wrote:
> > > > I have a string "Tue Nov 7 14:04:16 2006: Unable to open prev pos
> > > > file" in a variable "myvariable" and I need to extract "Tue Nov 7
> > > > 14:14:16 2006" to another variable..
> > > >
> > > > I also would like to know if there are any way to compare the above
> > > > result with Current date and find the difference of days/months
<snip>
> >
> > Or, if you didn't feel like doing all that work yourself, take
> > advantage of modules on CPAN, like Date::Manip...
> >
> > #!/usr/bin/perl
> > use strict;
> > use warnings;
> > use Date::Manip;
>
> Thanks Paul for your help, I tried running the script in my PC, but it
> says "Can't locate Date/Manip.pm in @INC (@INC contains:
<snip>
>
> So the system couldn't find manip.pm.
Manip.pm: case matters. In fact, Date/Manip.pm would be better, as the
error message said.
> Currently i am using 5.8.6 in mac
> OS X. Would appreciate your help if I can get to know what could be the
> solution for it...
You need to install the module from CPAN.
perldoc CPAN
perldoc ppm if you're using ActivePerl (I'm not sure: you said 'PC', by
which people usually mean 'Windows'; but you also said OSX...).
If you installed Perl through a package manager that may have a way of
installing Perl modules as well, that may be easier to use (or not :) ).
Ben
--
"Faith has you at a disadvantage, Buffy."
"'Cause I'm not crazy, or 'cause I don't kill people?"
"Both, actually."
[benmorrow@tiscali.co.uk]
------------------------------
Date: 24 Nov 2006 05:06:42 -0800
From: daniel.crosby@gmx.de
Subject: handling hanging database connections: timeout in perl
Message-Id: <1164373602.456186.236910@l12g2000cwl.googlegroups.com>
The eval does not seem to be enough to provoke a timeout on a hanging
oracle connection i.e. where i get no response. I do not understand why
this does not work in this perl example.
foreach $l_db (keys %{ $G_ALL_DB{$l_host}}) {
($l_ars, $l_ars_sev)= split /\|/, $G_ALL_DB{$l_host}{$l_db};
$l_startdb=time(); # = now
$G_COUNT_DB_CONNECT++;
eval { ### TRY ###
$l_erg="";
$l_exe_ok=0;
use DBI;
$ENV{ORACLE_HOME}=$G_CONF{DBHOME};
$SIG{ALRM} = sub {&ConnectTimeOut ($l_host, $l_db, $l_ars,
$l_ars_sev, $l_erg) };
alarm $G_CONF{TIMEOUT_DB_CONNECT};
$l_cstr="DBI:Oracle:$l_db";
$l_dbh = DBI->connect($l_cstr, $G_CONF{TEST_USER},
$G_CONF{TEST_PASS}, { PrintError=>0, RaiseError=>0, AutoCommit=>1 });
if ($l_dbh) {
if ($l_results= $l_dbh->prepare ($G_SEL_TIV_CONN_CHECK )) {
$l_results->execute;
$l_exe_ok=1;
# fetch rows
while (@l_row = $l_results->fetchrow_array) {
$l_erg=$l_row[0];
if ( $l_erg !~ /XOK/ ) {
$l_msg="$l_db Result doesn't match XOK";
@l_errstr=();
&ConnectFailed ($l_host, $l_db, $l_ars, $l_ars_sev, $l_msg,
@l_errstr);
} else {
&Logging (3, $I, $l_db, "Connect success. DB = $l_db");
$G_RESULTS_CONNECT{$l_db}="connect_succeeded";
}
}
}
$l_dbh->disconnect or &warn ("Can not close DB $l_db,
$DBI::errstr\n");
}
alarm 0;
};
if ($@) { ### CATCH exception ###
$l_err = $@;
$l_err =~ s/\n/ /g;
$l_msg = "$l_db Exception connecting : $l_err";
# Check for errors to ignore, alert the Rest
@l_errstr = grep $DBI::errstr =~ m/$_/, keys
%G_IGNORE_ORACLE_ERRORS;
&ConnectFailed ($l_host, $l_db, $l_ars, $l_ars_sev, $l_msg,
@l_errstr );
# &Logging (0, $A, "exception", $l_msg);
}
if ( $l_exe_ok != 1 ) {
$l_msg="$l_db Connect failure : $DBI::errstr";
# Check for errors to ignore, alert the Rest
@l_errstr = grep $DBI::errstr =~ m/$_/, keys
%G_IGNORE_ORACLE_ERRORS;
&ConnectFailed ($l_host, $l_db, $l_ars, $l_ars_sev, $l_msg,
@l_errstr );
}
------------------------------
Date: 24 Nov 2006 04:27:12 -0800
From: pod69@gmx.net
Subject: Re: How to read the Doctype Information out of an XML File
Message-Id: <1164371232.512212.162040@j72g2000cwa.googlegroups.com>
thank you very much for your example - that was what i was looking for
- now i have a better understanding of that!
DJ Stunks schrieb:
> pod69@gmx.net wrote:
> > DJ Stunks schrieb:
> > > pod69@gmx.net wrote:
> > > > Hello,
> > > >
> > > > How can i read the Doctype Information out of an xml file?
> > >
> > > I would use XML::Parser and write an Entity handler which pushed the
> > > Sysid onto a globally scoped array. After it has parsed the whole file
> > > your array will contain your entities.
> >
> > Do you have an example somewhere so i can see how it looks like because
> > i dont know what to do or do you have some code?
>
> [ please don't top post! quote an appropriate amount of context and
> then post your reply underneath]
>
> I thought my answer was pretty clear; if you're having a hard time
> understanding it then I suspect you will have a hard time completing
> your task. However, since I was curious I whipped this up.
>
> Enjoy!
>
> -jp
>
> #!/usr/bin/perl
>
> use strict;
> use warnings;
>
> use XML::Parser;
>
> my $xml = do{ local $/; <DATA> };
>
> my $parser
> = new XML::Parser(Handlers => { Entity => \&handle_entity });
>
> my @entities;
> $parser->parse( $xml );
>
> print "Entities:\n";
> print " $_\n" for @entities;
>
> sub handle_entity {
> @_{ qw(Expat Name Val Sysid Pubid Ndata IsParam) } = @_;
>
> push @entities, $_{Sysid};
>
> }
>
> __DATA__
> <!-- xq226.xml -->
> <!DOCTYPE poem [
> <!ENTITY ext1 SYSTEM "lines938-939.xml">
> ]>
> <poem>
> <verse>I therefore, I alone first undertook</verse>
> <verse>To wing the desolate Abyss, and spy</verse>
> &ext1;
> <verse>Better abode, and my afflicted Powers</verse>
> <verse>To settle here on Earth or in mid-air</verse>
> </poem>
------------------------------
Date: 24 Nov 2006 03:37:40 -0800
From: weer1@gmx.net
Subject: One texture Perl / OpenGL
Message-Id: <1164368260.445733.273310@45g2000cws.googlegroups.com>
Hi,
I want to do a texture on a polygon but I think I am missing something
here.
Nowhere in the code I see a connection with my polygon but the polygon
turns flickering black and green when I do enable the texture. I have
the code below now.
Any ideas?
MD
---------
...
glBegin(GL_POLYGON);
glVertex3f(0, 0, 1);
glVertex3f(0, 0.5, 1);
glVertex3f(1, 0, 1);
glEnd();
# make texture
my $img = new Imager;
$img->open(file=>'check.png', type=>'png'); # initializes
from file
my $texid = glGenTextures_p(1);
glBindTexture(GL_TEXTURE_2D, $texid);
glTexImage2D_c(GL_TEXTURE_2D, 0, 3, 32, 32, 0, GL_RGB, GL_BYTE,
$img); # not sure its _c
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_LINEAR);
glEnable(GL_TEXTURE_2D);
# glClearColor(0, 0.3, 0.6, 1);
#end texture
glPopMatrix();
glutSwapBuffers();
------------------------------
Date: 24 Nov 2006 08:10:17 GMT
From: tadmc@augustmail.com
Subject: Posting Guidelines for comp.lang.perl.misc ($Revision: 1.7 $)
Message-Id: <4566a8e9$0$81350$ae4e5890@news.nationwide.net>
Outline
Before posting to comp.lang.perl.misc
Must
- Check the Perl Frequently Asked Questions (FAQ)
- Check the other standard Perl docs (*.pod)
Really Really Should
- Lurk for a while before posting
- Search a Usenet archive
If You Like
- Check Other Resources
Posting to comp.lang.perl.misc
Is there a better place to ask your question?
- Question should be about Perl, not about the application area
How to participate (post) in the clpmisc community
- Carefully choose the contents of your Subject header
- Use an effective followup style
- Speak Perl rather than English, when possible
- Ask perl to help you
- Do not re-type Perl code
- Provide enough information
- Do not provide too much information
- Do not post binaries, HTML, or MIME
Social faux pas to avoid
- Asking a Frequently Asked Question
- Asking a question easily answered by a cursory doc search
- Asking for emailed answers
- Beware of saying "doesn't work"
- Sending a "stealth" Cc copy
Be extra cautious when you get upset
- Count to ten before composing a followup when you are upset
- Count to ten after composing and before posting when you are upset
-----------------------------------------------------------------
Posting Guidelines for comp.lang.perl.misc ($Revision: 1.7 $)
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.augustmail.com/~tadmc/clpmisc.shtml
For more information about netiquette in general, see the "Netiquette
Guidelines" at:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
A note to newsgroup "regulars":
Do not use these guidelines as a "license to flame" or other
meanness. It is possible that a poster is unaware of things
discussed here. Give them the benefit of the doubt, and just
help them learn how to post, rather than assume 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_group_search
If You Like
This section describes things that you *can* do before posting to
clpmisc.
Check Other Resources
You may want to check in books or on web sites to see if you can
find the answer to your question.
But you need to consider the source of such information: there are a
lot of very poor Perl books and web sites, and several good ones
too, of course.
Posting to comp.lang.perl.misc
There can be 200 messages in clpmisc in a single day. Nobody is going to
read every article. They must decide somehow which articles they are
going to read, and which they will skip.
Your post is in competition with 199 other posts. You need to "win"
before a person who can help you will even read your question.
These sections describe how you can help keep your article from being
one of the "skipped" ones.
Is there a better place to ask your question?
Question should be about Perl, not about the application area
It can be difficult to separate out where your problem really is,
but you should make a conscious effort to post to the most
applicable newsgroup. That is, after all, where you are the most
likely to find the people who know how to answer your question.
Being able to "partition" a problem is an essential skill for
effectively troubleshooting programming problems. If you don't get
that right, you end up looking for answers in the wrong places.
It should be understood that you may not know that the root of your
problem is not Perl-related (the two most frequent ones are CGI and
Operating System related), so off-topic postings will happen from
time to time. Be gracious when someone helps you find a better place
to ask your question by pointing you to a more applicable newsgroup.
How to participate (post) in the clpmisc community
Carefully choose the contents of your Subject header
You have 40 precious characters of Subject to win out and be one of
the posts that gets read. Don't waste them. Take care while
composing them, they are the key that opens the door to getting an
answer.
Spend them indicating what aspect of Perl others will find if they
should decide to read your article.
Do not spend them indicating "experience level" (guru, newbie...).
Do not spend them pleading (please read, urgent, help!...).
Do not spend them on non-Subjects (Perl question, one-word
Subject...)
For more information on choosing a Subject see "Choosing Good
Subject Lines":
http://www.cpan.org/authors/id/D/DM/DMR/subjects.post
Part of the beauty of newsgroup dynamics, is that you can contribute
to the community with your very first post! If your choice of
Subject leads a fellow Perler to find the thread you are starting,
then even asking a question helps us all.
Use an effective followup style
When composing a followup, quote only enough text to establish the
context for the comments that you will add. Always indicate who
wrote the quoted material. Never quote an entire article. Never
quote a .signature (unless that is what you are commenting on).
Intersperse your comments *following* each section of quoted text to
which they relate. Unappreciated followup styles are referred to as
"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 <tadmc@augustmail.com> and many others on the
comp.lang.perl.misc newsgroup.
------------------------------
Date: 24 Nov 2006 04:22:48 -0800
From: "Mark Tarver" <dr.mtarver@ukonline.co.uk>
Subject: the opposite of 'chop'
Message-Id: <1164370968.837623.72860@f16g2000cwb.googlegroups.com>
I understand 'chop' grabs the last token of a string. What grabs the
first?
Mark
------------------------------
Date: 24 Nov 2006 04:35:21 -0800
From: "Paul Lalli" <mritty@gmail.com>
Subject: Re: the opposite of 'chop'
Message-Id: <1164371721.786764.74670@k70g2000cwa.googlegroups.com>
Mark Tarver wrote:
> I understand 'chop' grabs the last token of a string.
You understand incorrectly. chop() does not "grab" the last character
in a string. It removes the last character from the string, and then
returns whatever that character was. That is, it directly modifies the
string you pass to it.
> What grabs the first?
There is no direct functional equivalent for the beginning of the
string. If you'd like, you can use substr:
my $first_char = substr($string,0,1, q{});
Paul Lalli
------------------------------
Date: Fri, 24 Nov 2006 11:55:19 +0000
From: Ben Morrow <benmorrow@tiscali.co.uk>
Subject: Re: what is the best choose fork or thread?
Message-Id: <763j34-fd7.ln1@osiris.mauzo.dyndns.org>
Quoth Martijn Lievaart <m@remove.this.part.rtij.nl>:
> On Thu, 23 Nov 2006 23:56:42 +0800, sonet wrote:
>
> > I have a project must send a lot of file in win2k at the same time.
> > But what is the best method in win32?
> > Can the perl build-in function fork work in win32?
> > Or the perl build-in thread is good solution
>
> Besides Anno's answer, be aware that threads have severe limitations. More
> to the point, threads and signals don't mix. So if you need timeouts (in
> Perl) or any other signal handling, you are pretty much stuck on forking.
>
> Other than that, in general threads are faster than forks. New threads are
> created faster
Do you have any evidence for this? While it may be true in general, it
is very much *not* true of Perl threads as currently implemented. For
instance, on my machine,
#!/usr/bin/perl
use threads;
use Benchmark qw/cmpthese/;
use POSIX qw/_exit/;
cmpthese -5, {
fork => sub {
my $p = fork;
if ($p) {
waitpid $p, 0;
}
else {
sub {
return;
}->();
_exit 0;
}
},
thread => sub {
async {
return;
}->join;
},
};
__END__
produces
Rate thread fork
thread 47.2/s -- -99%
fork 4451/s 9326% --
, so forking is an order of magnitude faster than threading. Perl
ithreads are basically an implementation of fork(2) in userspace, so
it's not surprising the OS can do it rather better.
> and interthread/process communication is generally faster.
This I would also expect to be false of Perl threads atm, but I can't be
bothered to devise a benchmark. Of course, if you are passing around
Perl data structures, it may be much easier to use threads; but even in
this case, I would advise looking at forks.pm instead.
Ben
--
"If a book is worth reading when you are six, * benmorrow@tiscali.co.uk
it is worth reading when you are sixty." [C.S.Lewis]
------------------------------
Date: Fri, 24 Nov 2006 14:31:33 +0100
From: Yohan N Leder <ynl@nsparks.net>
Subject: Re: what is the best choose fork or thread?
Message-Id: <MPG.1fd1129fcb32fb1a98990f@news.tiscali.fr>
In article <ek4gc0$82u$1@netnews.hinet.net>, sonet.all@msa.hinet.net
says...
> I have a project must send a lot of file in win2k at the same time.
> But what is the best method in win32?
> Can the perl build-in function fork work in win32?
> Or the perl build-in thread is good solution
>
From what I've seen, fork bugs with script in tainted mode under
ActivePerl 5.8.[7|8] for Windows. So, I'm used to go through fork unless
under Windows where I adapt code to go through Win32::Process.
------------------------------
Date: Fri, 24 Nov 2006 14:34:41 +0100
From: Yohan N Leder <ynl@nsparks.net>
Subject: Re: what is the best choose fork or thread?
Message-Id: <MPG.1fd113595e7b6348989910@news.tiscali.fr>
In article <MPG.1fd1129fcb32fb1a98990f@news.tiscali.fr>, ynl@nsparks.net
says...
> In article <ek4gc0$82u$1@netnews.hinet.net>, sonet.all@msa.hinet.net
> says...
> > I have a project must send a lot of file in win2k at the same time.
> > But what is the best method in win32?
> > Can the perl build-in function fork work in win32?
> > Or the perl build-in thread is good solution
> >
>
> From what I've seen, fork bugs with script in tainted mode under
> ActivePerl 5.8.[7|8] for Windows. So, I'm used to go through fork unless
> under Windows where I adapt code to go through Win32::Process.
>
Also, forget to say, "use threads;" falls in the same bug as fork in the
same case.
------------------------------
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