[18752] in Perl-Users-Digest
Perl-Users Digest, Issue: 920 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Thu May 17 06:05:56 2001
Date: Thu, 17 May 2001 03:05:12 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Message-Id: <990093911-v10-i920@ruby.oce.orst.edu>
Content-Type: text
Perl-Users Digest Thu, 17 May 2001 Volume: 10 Number: 920
Today's topics:
"listen" to a file <peter.sogaard@tjgroup.com>
Re: $myexp =~ s/\%/[aeiou]/; ???? <gerhard.schwarz@fpg.de>
-c: misses close FOO, or die "whatever" (cabney)
Re: -c: misses close FOO, or die "whatever" (Anno Siegel)
\n Woes <jtjohnston@courrier.usherb.ca>
Re: \n Woes <thelma@alpha2.csd.uwm.edu>
Re: \n Woes <wyzelli@yahoo.com>
Re: \n Woes <skilchen@swissonline.ch>
Re: \nhelp <jtjohnston@courrier.usherb.ca>
Re: \npeter <jtjohnston@courrier.usherb.ca>
An Example Of A Polite FAQ <godzilla@stomp.stomp.tokyo>
ANNOUNCE: Perl6::Variables 0.01 (Damian Conway)
Re: aol proxy (Dan Birchall)
Re: Beginner's Language? <reply-via@my-web-site.com>
Re: Bits and bytes (Dave Bailey)
ceil() function- inconsistent results <salo@coastside.net>
Re: ceil() function- inconsistent results (Tad McClellan)
device::SerialPortmodem wierd characters received after (Phil)
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Thu, 17 May 2001 11:12:38 +0200
From: "Peter Søgaard" <peter.sogaard@tjgroup.com>
Subject: "listen" to a file
Message-Id: <9e04lp$t0p$1@news.inet.tele.dk>
Hi,
Is it possible to have perl "listen to" a certain file, and then trigger
some event when this file is updated( i.e. overwritten ).
I can probably use sleep x seconds and then check the file status once in a
while and decide whether the file has been updated since last time i
checked...but is there a more correct way of doing this?...if so, how? :)
------------------------------
Date: Thu, 17 May 2001 11:06:51 +0200
From: Gerhard Schwarz <gerhard.schwarz@fpg.de>
Subject: Re: $myexp =~ s/\%/[aeiou]/; ????
Message-Id: <3B0394AB.46A15C57@fpg.de>
Hi,
> > $myexp =~ s/\%/[aeiou]/;
> >
> > I haven't found the meaning of that "%" (even on perldoc.com).
> > Maybe someone could explain it to me?
> I would scrap the example code and go elsewhere. There are plenty of
> good books and online tutorials to learn from.
I know, but this thing has to do with my job.
> But to answer you'r question if $myexp is a string containing something
> like
> "hi there you just scored 100%"
> then doing $myexp =~ s/%/[aeiou]/;
> would change it into "hi there you just scored 100[aeiou]"
> so you can see, this doesn't do what was probably intended.
> also note that you don't need the '\' infront of the % sign.
It's exactly what I thought of..., but in the context of the
code it make no sense.
> Just one question. Are you sure you've posted the correct code?
Sorry, hm, here's the complete loop:
$match is a String from 0 to n length, and does only contain
letters.
ruleset:
while (defined $REGEL[$fr]) {
for $r (@{$REGEL[$fr]}) {
next unless $r->[4] | $fc;
my $match = $r->[5];
$match =~ s/\+/[bcdfghjklmnpqrstvwxyz]/;
<> $match =~ s/\%/[aeiou\344\366\374]/;
#my $ns = $s.$e;
#$ns = substr($ns,0,length($ns)-$r->[1]);
#$e = substr($e, length($e)-$r->[1]);
print "\tREGEL: $fr:", (join ':', @{$r}),"\t($s,$match)\n"
if $debug > 1;
if ($s =~ /$match$/) {
$did_match++;
print "\tREGEL: $fr:", (join ':', @{$r}),"\t$s => "
if $debug;
$s = (substr($s,0,length($s)-$r->[7])) if $r->[7];
$s .= $r->[8] if $r->[8];
print "$s\n" if $debug;
if ($r->[6]) {
$v =~ s/^ge//;
}
$fr = $r->[0];
$fc = $r->[3];
if ($fr ne '000') {
next ruleset;
} else {
#$s = substr($s,0,length($s)-$r->[1]);
last;
}
}
}
last;
}
> Paul
I think a Book cannot help here? ;)
Gerhard
------------------------------
Date: Thu, 17 May 2001 08:26:35 GMT
From: cabney@vespidae.occultbias.net (cabney)
Subject: -c: misses close FOO, or die "whatever"
Message-Id: <slrn9g72q8.p9t.cabney@vespidae.occultbias.net>
As the subject line states, I have a short piece of code in which
close V, or die ("er, huh?: $!\n");
is valid syntax for perl -c... I even used both -w and 'use strict'.
I just can't see why perl shouldn't complain about that, and thought
if somebody might hit me with a camel jockey's prod to enlighten me.
Sorry about the munged Reply-To, a post is sufficient... :(
CA (will it be so in Perl v.6?)
--
There was a time
A wind that blew so young
For this could be the biggest sky
And I could have the faintest idea
------------------------------
Date: 17 May 2001 09:21:37 GMT
From: anno4000@lublin.zrz.tu-berlin.de (Anno Siegel)
Subject: Re: -c: misses close FOO, or die "whatever"
Message-Id: <9e0571$4h2$1@mamenchi.zrz.TU-Berlin.DE>
According to cabney <cabneySPAM@SPAM.SPAMcyberpass.net>:
> As the subject line states, I have a short piece of code in which
>
> close V, or die ("er, huh?: $!\n");
>
> is valid syntax for perl -c... I even used both -w and 'use strict'.
>
> I just can't see why perl shouldn't complain about that, and thought
> if somebody might hit me with a camel jockey's prod to enlighten me.
Arguably the syntax is fine. You have a comma operator in scalar
context whose right operand doesn't exist. In list context, the
comma operator without a right operand common fare, as in
my %h = (
a => 1,
b => 2,
);
The documented behavior is to ignore the extra comma.
While the documentation is silent about this construct in scalar
context, it seems at least reasonable to assume that a trailing
comma will be likewise ignored. After all, context can change
at runtime.
> Sorry about the munged Reply-To, a post is sufficient... :(
Spam is a nuisance, but a single bit won't explode your computer :)
Anno
------------------------------
Date: Thu, 17 May 2001 01:20:37 -0400
From: jtjohnston <jtjohnston@courrier.usherb.ca>
Subject: \n Woes
Message-Id: <3B035FA5.7EA60416@courrier.usherb.ca>
I have tempted this and failed. I wish to join any line that begins with && to
the previous line.
BEFORE:
Here is an example of before.
&&4; here is the second line.
AFTER:
Here is an example of after. &&4; here is the second line.
My code sort of works, but it doesn't restore every line?! Many are chopped
off. Here is the corpus of text I tested it on if anyone wishes to duplicate:
http://callisto.si.usherb.ca/~eslcafe/ccl-corpus.21-26.output.txt
Thanks,
John
#!perl -w
print "Content-type: text/html\n\n";
$file1 = "ccl-corpus.21-26.output.txt";
$file2 = "ccl-corpus.21-26.output2.txt";
if ( ! open(INPUT1,"<$file1") ) {die("Can't open file \"$file1\" :
$!\n");}
if ( ! open(OUTPUT,">$file2") ) {die("Can't create file \"$file2\" :
$!\n");}
while (my $line = <INPUT1>)
{
my $next = <INPUT1>;
while ($next =~ /^&&/) #note I'm searching for && to match &&4, &&5, etc.
{
chomp $line;
$line .= " $next";
$next = <INPUT1>;
}
$line = $next;
print OUTPUT "$line\n"; #AM I DOING THIS RIGHT?
# print OUTPUT "$next\n"; #AM I DOING THIS RIGHT?
print "$line<br>\n";
}
close INPUT1;
close OUTPUT;
------------------------------
Date: 17 May 2001 05:55:27 GMT
From: Thelma Lubkin <thelma@alpha2.csd.uwm.edu>
Subject: Re: \n Woes
Message-Id: <9dvp4f$rt$1@uwm.edu>
jtjohnston <jtjohnston@courrier.usherb.ca> wrote:
...
: BEFORE:
: Here is an example of before.
: &&4; here is the second line.
: AFTER:
: Here is an example of after. &&4; here is the second line.
: My code sort of works, but it doesn't restore every line?!
<snip>
: Thanks,
: John
<code snipped>
: while (my $line = <INPUT1>)
: {
: my $next = <INPUT1>;
You need to remove $next's \n:
chomp (my $next = <INPUT1>;
--thelma
------------------------------
Date: Thu, 17 May 2001 16:14:06 +0930
From: "Wyzelli" <wyzelli@yahoo.com>
Subject: Re: \n Woes
Message-Id: <MpKM6.37$uB1.4642@vic.nntp.telstra.net>
"jtjohnston" <jtjohnston@courrier.usherb.ca> wrote in message
news:3B035FA5.7EA60416@courrier.usherb.ca...
> I have tempted this and failed. I wish to join any line that begins with
&& to
> the previous line.
>
> BEFORE:
> Here is an example of before.
> &&4; here is the second line.
>
> AFTER:
> Here is an example of after. &&4; here is the second line.
>
> My code sort of works, but it doesn't restore every line?! Many are
chopped
> off. Here is the corpus of text I tested it on if anyone wishes to
duplicate:
> http://callisto.si.usherb.ca/~eslcafe/ccl-corpus.21-26.output.txt
>
> Thanks,
> John
Here's my approach:
open (IN, 'd:/perl/scripts/test/temp.txt') or die "Cant $!";
open (OUT, '>d:/perl/scripts/test/newtemp.txt') or die "Wont $!";
my $last;
my @lines = <IN>; # The file is only 461k
for (@lines){
chomp;
if ($last){ #make sure we have 'a' line
if (m/^&&/){ # If the next line starts with &&
$last = $last.$_; # join this and the last
next; # grab the next line
}
else
print OUT "$last\n"; # it didn't start with && so print the last
one
$last = $_; # grab the next line that doesn't start with &&
}
}
else {
$last = $_; # store the first line
}
}
Wyzelli
--
push@x,$_ for(a..z);push@x,' ';
@z='092018192600131419070417261504171126070002100417'=~/(..)/g;
foreach $y(@z){$_.=$x[$y]}y/jp/JP/;print;
------------------------------
Date: Thu, 17 May 2001 11:56:30 +0200
From: "Samuel Kilchenmann" <skilchen@swissonline.ch>
Subject: Re: \n Woes
Message-Id: <9e07b6$cka9$1@ID-13368.news.dfncis.de>
"Wyzelli" <wyzelli@yahoo.com> wrote in
news:MpKM6.37$uB1.4642@vic.nntp.telstra.net...
> "jtjohnston" <jtjohnston@courrier.usherb.ca> wrote in message
> news:3B035FA5.7EA60416@courrier.usherb.ca...
> > I have tempted this and failed. I wish to join any line that
> > begins with && to the previous line.
> >
> > BEFORE:
> > Here is an example of before.
> > &&4; here is the second line.
> >
> > AFTER:
> > Here is an example of after. &&4; here is the second line.
> >
>
> Here's my approach:
>
I like your approach with some modifications:
> open (IN, 'd:/perl/scripts/test/temp.txt') or die "Cant $!";
> open (OUT, '>d:/perl/scripts/test/newtemp.txt') or die "Wont $!";
> my $last;
> my @lines = <IN>; # The file is only 461k
No need to slurp the entire file into @lines
> for (@lines){
while (<IN>) {
> chomp;
> if ($last){ #make sure we have 'a' line
Here you are skipping empty lines which might be a feature. But if you
want to keep empty lines you have to check for defined($last)
> if (m/^&&/){ # If the next line starts with &&
> $last = $last.$_; # join this and the last
> next; # grab the next line
> }
> else {
> print OUT "$last\n"; # it didn't start with && so print the
> $last = $_; # grab the next line that doesn't start with &&
> }
> }
> else {
> $last = $_; # store the first line
> }
> }
>
Here you miss the last line.
if ($last) {
print OUT "$last\n";
}
Here's a similar approach:
my $buffer = <INPUT1>;
while (defined(my $line = <INPUT1>)) {
if ($line =~ /^&&/) {
chomp($buffer);
$buffer .= " $line";
}
else {
print OUTPUT $buffer;
$buffer = $line;
}
}
print OUTPUT $buffer;
------------------------------
Date: Thu, 17 May 2001 00:36:13 -0400
From: jtjohnston <jtjohnston@courrier.usherb.ca>
Subject: Re: \nhelp
Message-Id: <3B03553D.B88941FE@courrier.usherb.ca>
Sorry, I thought I cancelled the first one???? It is not listed here
anywhere, which means the group only received one?
J
------------------------------
Date: Thu, 17 May 2001 00:39:28 -0400
From: jtjohnston <jtjohnston@courrier.usherb.ca>
Subject: Re: \npeter
Message-Id: <3B035600.F1F130C6@courrier.usherb.ca>
Likely not small enough. 1.2 megs on a Windows NT server. Aaaagh. It would
choke.
Feel free to post an example that might do it for fun.
John
> If your file can fit in memory as a whole, just slurp it into a single
> scalar using any of the standard idioms, and then do
> $text =~ s/\n(?=&&4;)//g;
------------------------------
Date: Wed, 16 May 2001 22:11:56 -0700
From: "Godzilla!" <godzilla@stomp.stomp.tokyo>
Subject: An Example Of A Polite FAQ
Message-Id: <3B035D9C.5BC348C6@stomp.stomp.tokyo>
Welcome to comp.lang.perl.misc newsgroup!
This newsgroup, commonly called clpm, is a technical newsgroup
intended to be used for discussion of any and all Perl related
issues, whether it be comments or questions. This is an unmoderated
newsgroup and all are invited to drop in and visit, even if just
to say hello!
As a technical newsgroup, clpm is a bit different than most
general topic newsgroups. As you would expect, clpm discussions
are usually very technical in nature and there are some guidelines
for usage of this newsgroup which are somewhat different than
the average. This document provides information to assist you
in both obtaining the best usage of clpm and to help you have fun!
Before you read any further, if you are relatively new to
newsgroups, maybe could use some general advice on using
newsgroups, this is an excellent resource:
http://andrew2.andrew.cmu.edu/rfc/rfc1855.html
**********************************************************************
Table Of Contents
1. Before posting to comp.lang.perl.misc
1a. Check the Perl Frequently Asked Questions (FAQ)
1b. Check the other standard Perl docs (*.pod)
1c. Lurk for a while before posting
1d. Search a Usenet archive or discussion group
1e. Check Other Resources
2. Posting to comp.lang.perl.misc
2a. Articles should be related to Perl programming
2b. Carefully choose a Subject Line Topic
2c. Use an effective followup style
2d. Speak Perl Programming language when possible
2c. Do your machine homework first
2d. Be careful about typographical errors in code
2e. Provide just the right amount of information
2f. Avoid posting binaries, HTML, or MIME content
3. Social faux pas to avoid
3a. Asking a Frequently Asked Question
3b. Asking a question easily answered by a cursory doc search
3c. Asking for emailed answers
3d. Getting along with others
**********************************************************************
1. Before posting to comp.lang.perl.misc
________________________________________
1a. Check the Perl Frequently Asked Questions (FAQ)
A wonderful resource is avaiable for you. This resource
is a very comprehensive time tested collection of questions
most often asked. It is a resource written by long time
Perl professionals and provides quick easy to understand
answers to almost all questions you may have! You will
find answers here quicker than in clpm. Have a look!
( several links to mirror sites for Perl FAQ )
1b. Check the other standard Perl docs (*.pod)
Should you have Perl installed on your home machine or
have access to a Perl installation on your internet service
provider, you have an extremely extensive resource data base
right at your fingertips! Perl contains just about every bit
of information you could ever want to know about Perl, right
there behind your keyboard. Read your documentation for your
Perl installation at home, or ask your server how to access
these features. It is very simple! This is an extremely valuable
resource. There are great search features, lots of explanations,
all waiting there for you Don't overlook this!
If you experience difficulties in making use of this feature,
please feel free to visit clpm and ask how to do this! Lots
of folks will assist you, very quickly.
(possible examples of using the Perl search feature)
1c. Lurk for a while before posting
This is very important and is expected regardless of what newsgroup
you are visiting. Lurking means to simply monitor a newsgroup for
a period of time until you become very familiar with local customs.
Think of a newsgroup as foreign culture. Each newsgroup has its own
specific customs and rituals. Get to know those customs and rituals
well before you participate. This will help you to avoid embarrassing
social situations. Consider yourself to be a foreigner at first!
Mind your manners lest we toss you in pot and cook you for dinner!
1d. Search a Usenet archive or discussion group
There are tens of thousands of Perl programmers. It is very likely
your question has already been asked and answered many times! See
if you can find where it has already been answered. If you are making
a comment rather than asking a question, search the archives first!
You will discover many interesting coversations about many topics
related to Perl. Do your homework and make a great impression!
Some searchable archives are:
(list archives and discussion group links)
1e. Check Other Resources
You may want to check in books or at web sites to see if you can
find an answer to your question or become more knowledgable about
a specific Perl related topic for general discussion.
(short list of Perl sites and Perl book list sites)
2. Posting to comp.lang.perl.misc
_________________________________
2a. Is there a better place to ask your question?
Questions should be related to Perl programming as this is the
intent of the clpm newsgroup.
It can be challenging to ascertain what is your actual programming
problem. It might be Perl related or something which appears to be
Perl related but is not. Make a conscious effort to determine if your
concern is actually Perl related. There are many technical newsgroup
covering just about everything concerning computers and programming.
If you suspect your problem is Perl related, drop in and ask! If you
have a hunch it is something else, perhaps an operating system problem
or perhaps a server problem, work at locating a newsgroup related to
those topics. You will attain faster and better answers in newsgroup
directly related to your topic. If you are completely unsure, visit
this newsgroup and ask for assistance. Many will direct you to better
resources, to better newsgroups.
Sometimes we need help simply finding a problem. There are many methods
for narrowing a problem area in a program. Do a little research and you
will find lots of good advice on pinpointing a problem. Feel free to
drop in and ask about ways to narrow down a problem. We will help.
2b. Carefully choose the contents of your Subject header
Choosing a good Subject Line Topic is truly an art. Give careful
consideration
to your topic line. Work at keeping it as short as possible yet describe your
topic clearly and concisely. There is no need for complete sentences nor even
perfect grammar. Keep it short, sweet and descriptive. Do avoid using
expressions
like, "Help! I am a newbie!" or "URGENT! I need help!". This is guarantee
your
article will never be read and possibly, you may find yourself in trouble!
As an example, if your program won't open a file to read, use a topic like,
"File open failure" rather than "It won't work!"
These are very good resources to assist you in choosing a topic:
(list of several sites discussing subject line topics)
2c. Use an effective followup style
When composing a followup, quote only enough text of a responding
author to establish context for comments you will add. Always
indicate who wrote the quoted material. Never quote an entire
article. Never quote a signature or signature file. Edit! Edit!
Edit previous comments down to a bare minimum with still retaining
just enough to provide correct context.
Keep everything in the original chronological order just like you
are having a real time conversation! Attributes to an author come
first so everyone will know who wrote what. Another person's comment
comes next followed by your comment. Their comment, your comment.
Their comment, your comment. Get the picture? Just like talking.
Here is a good resource on quoting styles and response methods:
http://www.geocities.com/nnqweb/nquote.html
2d. Speak Perl Programming language when possible
Perl is inherently a technical programming language. Try to speak
in Perl as best you can! This, everyone will understand. Write out
your problem using Perl code as much as possible. Very often, a little
code goes a long ways in finding a problem. Add explanations as needed
but try to keep Perl code and explanations sorted out, separated.
Avoid this: I have variable with "foo\tbar" in it.
Use this: I have $var = "foo\tbar".
You see! Now everyone knows your variable name and can watch
for problems associated with that variable name.
2c. Do your machine homework first
You can ask perl itself to help you find common programming mistakes!
Perl has numerous built-in functions which will warn you about possible
mistakes, even tell you what is your mistake! Use these features!
These are a few examples of how Perl can help you.
enable warnings (perldoc warnings)
enable strictures (perldoc strict)
use diagnostics
Your Perl resources, such as books, internet sites, your own Perl
installation can help you learn how to use these helpful functions
and many more. They are great! They will tell you what is wrong and
won't even call you dummy! If you need help in this area, drop right
on into clpm and ask! Lots of good advice can be had for the asking.
2d. Be careful about typographical errors in code
Use copy and paste methods or your editor's "import" function rather
than attempt to type in your code. It is very easy to make a typical
typographical error which can make a major difference in your code.
Be sure your code is the actual code you are using, absolute verbatim.
2e. Provide just the right amount of information
Narrow your problem area down to as little Perl code as possible,
code which can still be tested on a machine, this is, at least
compiles without any errors, especially fatal errors.
Most clpm regulars will copy your code directly from your article
and test it. Be sure it works. This is very important.
There is a very nice aspect of doing these things. Quite often
you will discover your problem right off by localizing it to
very a specific section of your program.
Carefully describe input to your program. Make sure it is very
clear and concise; set good parameters. Also provide example
input data for your program. If you need to show file input,
use the __DATA__ token (perldata.pod) to provide disk drive
file contents for your Perl program. An alternative is to
simple include,
This is my input data: "Insert your data precisely!"
Display your output verbatim, including the exact text of any
warning or error messages you receive.
Provide a description of what you expect your program to output
but is not. This is very helpful. Include your expected results.
If you simply cannot figure out how to code a function, just don't
know how to do something with code, describe what you intend to
input and describe what you expect for output. This "stuff" goes
in and I want this "stuff" to come out! Lots of people can quickly
show you many different ways to attain your goal.
Sometimes people post too much code. Avoid posting an entire program.
Keep it short as possible. Too much code can be very difficult to
read and understand. KISS. Keep It Simple Silly!
2f. Avoid posting binaries, HTML, or MIME content
Never, never, NEVER post any binaries such as pictures and sound
files nor html enabled posts or encoded posts. Always post in
plaintext, old fashion typewriter text. This is a Golden Rule!
3. Social faux pas to avoid
3a. Asking a Frequently Asked Question
People understand you may have missed an applicable FAQ when you
checked, which is not a big deal. But if a Frequently Asked Question
is worded similar to your own question, some folks might assume you
did not look at all. Don't become indignant if pointers to a FAQ are
provided. This is quite common and is human nature.
3b. Asking a question easily answered by a cursory resource search
There will be times people might assume you did not do your homework
by researching available resources before posting your article. This
might be a simple misunderstanding or maybe you didn't do your homework!
Don't be surprised if some become a little cranky and perhaps express
some harsh words. There are lots of people out there who don't do there
homework and deserve to be chastised. Be sure to do your homework, be
sure to word your Subject Topic Line carefully and give good thought
to how you ask a question so others will know you have done your part.
3c. 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.
Your best bet is simply to never ask for an email response.
3d. Getting along with others
This is always a tough topic to address. You are an adult and
expect to be treated as such. Treat others the same. Getting
along with others is a simple matter of being polite and
courtesy, as you are anyhow.
As you know, there are trouble makers everywhere on the net,
everywhere in life. Our newsgroup is no exception. There are
trouble makers around. This is the nature of reality. Please
work at ignoring these people, please don't allow them to
anger you and prompt you to respond with harsh words. These
situations are trying but your best weapon is to ignore a
person who is causing trouble; deny troublemakers attention.
Doing this will help you avoid becoming one yourself.
Godzilla!
------------------------------
Date: 17 May 2001 07:33:48 GMT
From: damian@cs.monash.edu.au (Damian Conway)
Subject: ANNOUNCE: Perl6::Variables 0.01
Message-Id: <9dvuss$j3u$1@towncrier.cc.monash.edu.au>
Keywords: perl, module, release
==============================================================================
Release of version 0.01 of Perl6::Variables
==============================================================================
NAME
Perl6::Variables - Perl 6 variable syntax for Perl 5
DESCRIPTION
The Perl6::Variables module lets you try out the new Perl variable
access syntax in Perl 5.
AUTHOR
Damian Conway (damian@conway.org)
COPYRIGHT
Copyright (c) 2001, Damian Conway. All Rights Reserved. This module is
free software. It may be used, redistributed and/or modified under the
terms of the Perl Artistic License (see
http://www.perl.com/perl/misc/Artistic.html)
==============================================================================
CHANGES IN VERSION 0.01
(No changes have been documented for this version)
==============================================================================
AVAILABILITY
Perl6::Variables has been uploaded to the CPAN
and is also available from:
http://www.csse.monash.edu.au/~damian/CPAN/Perl6-Variables.tar.gz
==============================================================================
------------------------------
Date: 17 May 2001 08:05:25 GMT
From: djb@y77459fe5.scream.org (Dan Birchall)
Subject: Re: aol proxy
Message-Id: <slrn9g71t3.vch.djb@v2000.scream.org>
Patrick Joyce <joycefive@earthlink.net> wrote:
> i have a problem. what is up with aols proxy servers i have
> written a perl script that needs a uniqe host name. but with
> aol proxy the hostnames change often, how do i fix this and
> or why is this
Without knowing the internals of AOL's systems personally, I would
guess that due to their huge userbase, a single proxy doesn't
suffice, and they need to continually load-balance traffic across
multiple proxies.
You didn't say what your script did that depended on a unique host
name, but I would caution against using hostname as the key, or a
key, to a user session or anything similar.
As much as you might want there to be a one-to-one relationship
between user and hostname, and as much as that might be the case
most of the time on a low-traffic site, the model will break nastily
on a higher-traffic site. And it's not just AOL.
1. If Joe is a dialup user of example.com, he might connect to your
site from modem1.dial.example.com, get disconnected by an incoming
call, timeout, or whatever, redial, and wind up reconnecting to
modem2.dial.example.com, all within a short period of time (1 to
2 minutes). This is another 1 user : multiple hosts relationship,
similar to what you're encountering with the AOL proxies.
2. If Joe is an employee of example.com, and their corporate network
is firewalled and uses NAT for addresses in IANA reserved space,
he might show up as coming from gateway.example.com, regardless
of which computer he used within the company. And his co-workers
would *also* show up as coming from gateway.example.com, potentially
at the same, or overlapping, times. This is the inverse of your
problem, a multiple users : 1 host relationship.
3. Of course, with situations like #1 or AOL, you can also get into
multiple users : multiple hosts relationships. Maybe when Joe
got disconnected in example 1, the whole modem bank power-cycled,
also knocking off Jim, who had been on modem2.dial.example.com,
and when Jim redialed, he got modem1.dial.example.com. Wham, Joe
and Jim have switched hostnames.
So anyway, like I said up yonder, I'd caution against using hostname
as a key for... well, anything.
-Dan
--
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------------------------------
Date: Thu, 17 May 2001 10:20:21 +0200
From: "Biep @ http://www.biep.org/" <reply-via@my-web-site.com>
Subject: Re: Beginner's Language?
Message-Id: <9e01ge$aqom$1@ID-63952.news.dfncis.de>
"Lex Spoon" <lex@cc.gatech.edu> wrote in message
news:m3ae4dyyck.fsf@chaos.resnet.gatech.edu...
> If the learner is happy averaging lists of numbers
> and generating sentences and things like that,
> then Scheme is a wonderful place to start,
> but many beginners would be happier playing with graphical objects..
.. and for them (PLT) Scheme is a wonderful place to start.
--
Biep
Reply via http://www.biep.org
------------------------------
Date: 17 May 2001 07:52:29 GMT
From: dave@sydney.daveb.net (Dave Bailey)
Subject: Re: Bits and bytes
Message-Id: <slrn9g6mi6.20f.dave@sydney.daveb.net>
On Wed, 16 May 2001 23:17:25 GMT, James Weisberg <chadbour@wwa.com> wrote:
[...]
> Here is what I have coded so far:
[...]
>Let me show a couple examples:
>
># -> ./encode.pl 20010315 0 1 10 100 1 00 0 -1
>ird=20010315, size=8, length=11
>bitstr: (001100000011001001111011001010111011001010001000)
>[7] packet: (20010315,0,1,10,100,100,0,-1)
># -> ./encode.pl 20010315 9 1 10 100 1 00 0 -1
>ird=20010315, size=8, length=6
>bitstr: (01000001)
>[7] packet: (20010315,9,-1,-1,-1,-1,-1,-1)
>
>The first argument is the ird, and the second argument is a status flag for
>the entire record. As you can see, if the flag is nonzero, I encode a string
>which keeps the flag intact and I get a packet of -1s back. This instruction
>is the II = 01 instruction from what I described in my previous post.
Well, I can squeeze about a factor of 4.5 out of dbrec_pack and a factor
of about 2.5 out of dbrec_unpack by modifying them so that they operate
two bits at a time (below). These factors are for the array
my @a = (20010315,0,1,10,100,1,0,0,-1);
For the other array,
my @a = (20010315,9,1,10,100,1,0,0,-1);
I can only get about a 20 to 30% speedup, but packing and unpacking those
records is much faster than packing valid records, it seems. I don't
think it can get much faster in Perl. If unpacking speed is still a
bottleneck, you'll have to go to XS and C.
sub dbrec_pack2 {
my $ird = pack("l", shift);
my $v = '';
vec($v,0,8)=2+$#_; # recsize
if($_[0]) {
if($_[0] > 16) { print "$_[0] overflow\n"; exit }
else { vec($v,2,4)=2; vec($v,3,4)=$_[0]-1 }
} else {
my $o = 4;
for ( @_ ) {
if ( $_ == 0 ) { vec($v,$o++,2) = 0 }
elsif ( $_ == -1 ) { vec($v,$o++,2) = 1 }
elsif ( $_ <= 16843024 ) {
my ($a,$b,$c,$d) = ($_,0,0,0);
if ( $a <= 16 ) { $b = 1; $c = 4; $d = 0 }
elsif ( $a <= 272 ) { $b = 17; $c = 8; $d = 1 }
elsif ( $a <= 65808 ) { $b = 273; $c = 16; $d = 2 }
elsif ( $a <= 16843024 ) { $b = 65809; $c = 24; $d = 3 }
$a -= $b;
vec($v,$o++,2) = 3;
vec($v,$o++,2) = $d;
for ( my $i=0; $i<$c; $i+=2 ) {
vec($v,$o++,2) = $a >> $i;
}
} else { print "$_ overflow\n"; exit }
}
}
return $ird.$v; # concatenate ird and vector
}
sub dbrec_unpack2 {
my ($ird,$sz,$v) = (unpack("lC",$_[0]),substr($_[0],5));
my @l = ( 4, 8, 16, 24 );
my @s = ( 1, 17, 273, 65809 );
my @p = ( $ird );
my $o = 0;
foreach ( 1..$sz-1 ) {
my $n = vec($v,$o++,2);
if ( $n == 0 ) { push ( @p, 0 ) }
elsif ( $n == 1 ) { push ( @p, -1 ) }
elsif ( $n == 2 ) {
my $m; map { $m |= vec($v,$o++,2)<<$_ } (0..3);
push ( @p, $m+1, (-1)x($sz-2) );
last;
} elsif ( $n == 3 ) {
my $k;
$n = vec($v,$o++,2);
for ( my $j=0; $j < $l[$n]; $j+=2 ) {
$k |= vec($v,$o++,2)<<$j;
}
push ( @p, $k+$s[$n] );
}
}
return @p;
}
--
Dave Bailey
davidb54@yahoo.com
------------------------------
Date: Wed, 16 May 2001 21:44:56 -0700
From: "Michael J. Salo" <salo@coastside.net>
Subject: ceil() function- inconsistent results
Message-Id: <tg6jvbobfvha9b@corp.supernews.com>
Hey all
I'm getting unreliable results from the ceil() function in Perl 5. Some
specific values are being evaluated incorrectly. Either I'm not
understanding the function or it's buggy. Have a look at the following:
ceil(1942) evaluates to 1942 (correct)
ceil(10 * 194.2) evaluates to 1942 (correct)
ceil(100 * 19.42) evaluates to 1943 (incorrect)
ceil(1000 * 1.942) evaluates to 1942 (correct)
Any insights? Further demonstration is at
http://strangefortune.com/cgi-bin/ceil.cgi
Michael J. Salo
------------------------------
Date: Thu, 17 May 2001 00:08:28 -0400
From: tadmc@augustmail.com (Tad McClellan)
Subject: Re: ceil() function- inconsistent results
Message-Id: <slrn9g6jls.ono.tadmc@tadmc26.august.net>
Michael J. Salo <salo@coastside.net> wrote:
[ snip about POSIX::ceil function ]
>Either I'm not
>understanding the function or it's buggy.
It is neither of those :-)
>Any insights?
I think running this program will provide some:
--------------------------
#!/usr/bin/perl -w
use strict;
printf "%30.20f\n", 1942;
printf "%30.20f\n", 10 * 194.2;
printf "%30.20f\n", 100 * 19.42;
printf "%30.20f\n", 1000 * 1.942;
--------------------------
output:
1942.00000000000000000000
1942.00000000000000000000
1942.00000000000022737368
1942.00000000000000000000
Then have a look at the Perl FAQ, part 4:
"Why am I getting long decimals (eg, 19.9499999999999) instead
of the numbers I should be getting (eg, 19.95)?"
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: 17 May 2001 08:39:50 GMT
From: eclipsephil@aol.comnospam (Phil)
Subject: device::SerialPortmodem wierd characters received after reset
Message-Id: <20010517043950.04979.00000139@ng-mh1.aol.com>
I am using mandrake linux a us robotics sportster voice 33.6 fax modem, perl
5.6.0 and device::SerialPort v.0.10
I can initialise my call out and perform the first operation fine. However
when I or the other end drop the line I seem to have problems with wierd
characters in the buffer. ie if I do something like this simplified version
(note I'm not worried about parameters just for this question)
do {
setup modem;
write_modem;
waitfor;
down_line;
} (while $running);
I get characters like below (the =(n) is the ascii number of the char)
NL = (10) e = (101) ÿ = (255)
or
NUL = (0) " = (34) ÿ = (255)
Interestingly enough I am using 7 bit ascii so I should only be seeing
characters upto ascii 127 as this is the highest number you can transmit in one
7bit byte. This leads me to beleive that the ascii 255 comes from the modem
which I beleive represents the line going down. However I can trap that but I
keep getting a few sets of several characters before I can get an empty buffer.
The code I have used to down the line is below. My question is how can I
reset the modem so when I start up again the buffers are completely clear.
sub modem_write {
my $string = shift;
aborter ("write modem:no string to send") if (! (defined $string) );
my $len_string = length($string);
my $sent_bytes;
eval { $sent_bytes=$modem_obj->write($string) };
if ($@) {
$dbg->$dbg_method ("write failed with $! ");
return;
} elsif (! (defined $sent_bytes) ) {
$dbg->$dbg_method("send 0 bytes");
return;
} elsif ($sent_bytes != $len_string ) {
$dbg->$dbg_method("send $sent_bytes but record is
$len_string");
return;
}
return 1;
} # modem_write
sub downline {
$dbg->$dbg_method("Downline the phone");
modem_write("$dle.$eot\r\n");
modem_write("+++");
sleep(3);
modem_write('ATZ\r\n\n'); # note sure about this one
sleep(3);
$modem_status = 'Offline';
eval { $modem_obj->close; };
undef $modem_obj;
} # end of downline
Live the Journey!
For each destination is but a doorway to another!
------------------------------
Date: 6 Apr 2001 21:33:47 GMT (Last modified)
From: Perl-Users-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Digest Administrivia (Last modified: 6 Apr 01)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V10 Issue 920
**************************************
