[9769] in Perl-Users-Digest
Perl-Users Digest, Issue: 3362 Volume: 8
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Aug 5 09:17:22 1998
Date: Wed, 5 Aug 98 06:09:58 -0700
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 5 Aug 1998 Volume: 8 Number: 3362
Today's topics:
perlfaq9 - Networking (part 9 of 9) <perlfaq-suggestions@mox.perl.com>
Re: Problem with $/ and \x0D on Win32 (Bob Lanteigne)
Re: Problems with File::Find <tchrist@mox.perl.com>
Re: Problems with File::Find <perlguy@inlink.com>
Re: Suggestion: file handle associated $\ (Bart Lateur)
Re: unravelling (?=...), but what's the frog's motivati <rick.delaney@shaw.wave.ca>
Re: wtf is the obsession with "foo" and "bar" <adam@fastfare.co.uk>
Re: wtf is the obsession with "foo" and "bar" (Michael J Gebis)
Special: Digest Administrivia (Last modified: 12 Mar 98 (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: 5 Aug 1998 12:31:00 GMT
From: Tom Christiansen <perlfaq-suggestions@mox.perl.com>
Subject: perlfaq9 - Networking (part 9 of 9)
Message-Id: <6q9ja4$2ak$1@csnews.cs.colorado.edu>
+-----------------------------------------------------------------------+
| The following document was generated from its original pod using |
| the pod2text program included with the standard perl release, plus |
| small cosmetic mark-ups. The FAQ is also distributed with all Perl |
| releases as standard manpages; their latest versions can be retrieved |
| from http://language.perl.com/misc/faqs.tar.gz if you'd like. |
+-----------------------------------------------------------------------+
NAME
perlfaq9 - Networking ($Revision: 1.20 $, $Date: 1998/06/22
18:31:09 $)
DESCRIPTION
This section deals with questions related to networking, the
internet, and a few on the web.
My CGI script runs from the command line but not the browser.
(500 Server Error)
If you can demonstrate that you've read the following FAQs and that
your problem isn't something simple that can be easily answered,
you'll probably receive a courteous and useful reply to your
question if you post it on comp.infosystems.www.authoring.cgi (if
it's something to do with HTTP, HTML, or the CGI protocols).
Questions that appear to be Perl questions but are really CGI ones
that are posted to comp.lang.perl.misc may not be so well received.
The useful FAQs and related documents are:
CGI FAQ
http://www.webthing.com/page.cgi/cgifaq
Web FAQ
http://www.boutell.com/faq/
WWW Security FAQ
http://www.w3.org/Security/Faq/
HTTP Spec
http://www.w3.org/pub/WWW/Protocols/HTTP/
HTML Spec
http://www.w3.org/TR/REC-html40/
http://www.w3.org/pub/WWW/MarkUp/
CGI Spec
http://www.w3.org/CGI/
CGI Security FAQ
http://www.go2net.com/people/paulp/cgi-security/safe-cgi.txt
How can I get better error messages from a CGI program?
Use the CGI::Carp module. It replaces `warn' and `die', plus the
normal Carp modules `carp', `croak', and `confess' functions with
more verbose and safer versions. It still sends them to the normal
server error log.
use CGI::Carp;
warn "This is a complaint";
die "But this one is serious";
The following use of CGI::Carp also redirects errors to a file of
your choice, placed in a BEGIN block to catch compile-time warnings
as well:
BEGIN {
use CGI::Carp qw(carpout);
open(LOG, ">>/var/local/cgi-logs/mycgi-log")
or die "Unable to append to mycgi-log: $!\n";
carpout(*LOG);
}
You can even arrange for fatal errors to go back to the client
browser, which is nice for your own debugging, but might confuse
the end user.
use CGI::Carp qw(fatalsToBrowser);
die "Bad error here";
Even if the error happens before you get the HTTP header out, the
module will try to take care of this to avoid the dreaded server
500 errors. Normal warnings still go out to the server error log
(or wherever you've sent them with `carpout') with the application
name and date stamp prepended.
How do I remove HTML from a string?
The most correct way (albeit not the fastest) is to use HTML::Parse
from CPAN (part of the libwww-perl distribution, which is a must-
have module for all web hackers).
Many folks attempt a simple-minded regular expression approach,
like `s/<.*?>//g', but that fails in many cases because the tags
may continue over line breaks, they may contain quoted angle-
brackets, or HTML comment may be present. Plus folks forget to
convert entities, like `<' for example.
Here's one "simple-minded" approach, that works for most files:
#!/usr/bin/perl -p0777
s/<(?:[^>'"]*|(['"]).*?\1)*>//gs
If you want a more complete solution, see the 3-stage striphtml
program in
http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/striphtml
.gz .
Here are some tricky cases that you should think about when picking
a solution:
<IMG SRC = "foo.gif" ALT = "A > B">
<IMG SRC = "foo.gif"
ALT = "A > B">
<!-- <A comment> -->
<script>if (a<b && a>c)</script>
<# Just data #>
<![INCLUDE CDATA [ >>>>>>>>>>>> ]]>
If HTML comments include other tags, those solutions would also
break on text like this:
<!-- This section commented out.
<B>You can't see me!</B>
-->
How do I extract URLs?
A quick but imperfect approach is
#!/usr/bin/perl -n00
# qxurl - tchrist@perl.com
print "$2\n" while m{
< \s*
A \s+ HREF \s* = \s* (["']) (.*?) \1
\s* >
}gsix;
This version does not adjust relative URLs, understand alternate
bases, deal with HTML comments, deal with HREF and NAME attributes
in the same tag, or accept URLs themselves as arguments. It also
runs about 100x faster than a more "complete" solution using the
LWP suite of modules, such as the
http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/xurl.gz
program.
How do I download a file from the user's machine? How do I open a
file on another machine?
In the context of an HTML form, you can use what's known as
multipart/form-data encoding. The CGI.pm module (available from
CPAN) supports this in the start_multipart_form() method, which
isn't the same as the startform() method.
How do I make a pop-up menu in HTML?
Use the <SELECT> and <OPTION> tags. The CGI.pm module (available
from CPAN) supports this widget, as well as many others, including
some that it cleverly synthesizes on its own.
How do I fetch an HTML file?
One approach, if you have the lynx text-based HTML browser
installed on your system, is this:
$html_code = `lynx -source $url`;
$text_data = `lynx -dump $url`;
The libwww-perl (LWP) modules from CPAN provide a more powerful way
to do this. They work through proxies, and don't require lynx:
# simplest version
use LWP::Simple;
$content = get($URL);
# or print HTML from a URL
use LWP::Simple;
getprint "http://www.sn.no/libwww-perl/";
# or print ASCII from HTML from a URL
use LWP::Simple;
use HTML::Parse;
use HTML::FormatText;
my ($html, $ascii);
$html = get("http://www.perl.com/");
defined $html
or die "Can't fetch HTML from http://www.perl.com/";
$ascii = HTML::FormatText->new->format(parse_html($html));
print $ascii;
How do I automate an HTML form submission?
If you're submitting values using the GET method, create a URL and
encode the form using the `query_form' method:
use LWP::Simple;
use URI::URL;
my $url = url('http://www.perl.com/cgi-bin/cpan_mod');
$url->query_form(module => 'DB_File', readme => 1);
$content = get($url);
If you're using the POST method, create your own user agent and
encode the content appropriately.
use HTTP::Request::Common qw(POST);
use LWP::UserAgent;
$ua = LWP::UserAgent->new();
my $req = POST 'http://www.perl.com/cgi-bin/cpan_mod',
[ module => 'DB_File', readme => 1 ];
$content = $ua->request($req)->as_string;
How do I decode or create those %-encodings on the web?
Here's an example of decoding:
$string = "http://altavista.digital.com/cgi-bin/query?pg=q&what=news&fmt=.&q=%2Bcgi-bin+%2Bperl.exe";
$string =~ s/%([a-fA-F0-9]{2})/chr(hex($1))/ge;
Encoding is a bit harder, because you can't just blindly change all
the non-alphanumunder character (`\W') into their hex escapes. It's
important that characters with special meaning like `/' and `?'
*not* be translated. Probably the easiest way to get this right is
to avoid reinventing the wheel and just use the URI::Escape module,
which is part of the libwww-perl package (LWP) available from CPAN.
How do I redirect to another page?
Instead of sending back a `Content-Type' as the headers of your
reply, send back a `Location:' header. Officially this should be a
`URI:' header, so the CGI.pm module (available from CPAN) sends
back both:
Location: http://www.domain.com/newpage
URI: http://www.domain.com/newpage
Note that relative URLs in these headers can cause strange effects
because of "optimizations" that servers do.
$url = "http://www.perl.com/CPAN/";
print "Location: $url\n\n";
exit;
To be correct to the spec, each of those `"\n"' should really each
be `"\015\012"', but unless you're stuck on MacOS, you probably
won't notice.
How do I put a password on my web pages?
That depends. You'll need to read the documentation for your web
server, or perhaps check some of the other FAQs referenced above.
How do I edit my .htpasswd and .htgroup files with Perl?
The HTTPD::UserAdmin and HTTPD::GroupAdmin modules provide a
consistent OO interface to these files, regardless of how they're
stored. Databases may be text, dbm, Berkley DB or any database with
a DBI compatible driver. HTTPD::UserAdmin supports files used by
the `Basic' and `Digest' authentication schemes. Here's an example:
use HTTPD::UserAdmin ();
HTTPD::UserAdmin
->new(DB => "/foo/.htpasswd")
->add($username => $password);
How do I make sure users can't enter values into a form that cause my
CGI script to do bad things?
Read the CGI security FAQ, at http://www-
genome.wi.mit.edu/WWW/faqs/www-security-faq.html, and the Perl/CGI
FAQ at http://www.perl.com/CPAN/doc/FAQs/cgi/perl-cgi-faq.html.
In brief: use tainting (see the perlsec manpage), which makes sure
that data from outside your script (eg, CGI parameters) are never
used in `eval' or `system' calls. In addition to tainting, never
use the single-argument form of system() or exec(). Instead, supply
the command and arguments as a list, which prevents shell globbing.
How do I parse a mail header?
For a quick-and-dirty solution, try this solution derived from page
222 of the 2nd edition of "Programming Perl":
$/ = '';
$header = <MSG>;
$header =~ s/\n\s+/ /g; # merge continuation lines
%head = ( UNIX_FROM_LINE, split /^([-\w]+):\s*/m, $header );
That solution doesn't do well if, for example, you're trying to
maintain all the Received lines. A more complete approach is to use
the Mail::Header module from CPAN (part of the MailTools package).
How do I decode a CGI form?
You use a standard module, probably CGI.pm. Under no circumstances
should you attempt to do so by hand!
You'll see a lot of CGI programs that blindly read from STDIN the
number of bytes equal to CONTENT_LENGTH for POSTs, or grab
QUERY_STRING for decoding GETs. These programs are very poorly
written. They only work sometimes. They typically forget to check
the return value of the read() system call, which is a cardinal
sin. They don't handle HEAD requests. They don't handle multipart
forms used for file uploads. They don't deal with GET/POST
combinations where query fields are in more than one place. They
don't deal with keywords in the query string.
In short, they're bad hacks. Resist them at all costs. Please do
not be tempted to reinvent the wheel. Instead, use the CGI.pm or
CGI_Lite.pm (available from CPAN), or if you're trapped in the
module-free land of perl1 .. perl4, you might look into cgi-lib.pl
(available from http://www.bio.cam.ac.uk/web/form.html).
Make sure you know whether to use a GET or a POST in your form.
GETs should only be used for something that doesn't update the
server. Otherwise you can get mangled databases and repeated
feedback mail messages. The fancy word for this is ``idempotency''.
This simply means that there should be no difference between making
a GET request for a particular URL once or multiple times. This is
because the HTTP protocol definition says that a GET request may be
cached by the browser, or server, or an intervening proxy. POST
requests cannot be cached, because each request is independent and
matters. Typically, POST requests change or depend on state on the
server (query or update a database, send mail, or purchase a
computer).
How do I check a valid mail address?
You can't, at least, not in real time. Bummer, eh?
Without sending mail to the address and seeing whether there's a
human on the other hand to answer you, you cannot determine whether
a mail address is valid. Even if you apply the mail header
standard, you can have problems, because there are deliverable
addresses that aren't RFC-822 (the mail header standard) compliant,
and addresses that aren't deliverable which are compliant.
Many are tempted to try to eliminate many frequently-invalid mail
addresses with a simple regexp, such as `/^[\w.-]+\@([\w.-
]\.)+\w+$/'. It's a very bad idea. However, this also throws out
many valid ones, and says nothing about potential deliverability,
so is not suggested. Instead, see
http://www.perl.com/CPAN/authors/Tom_Christiansen/scripts/ckaddr.gz
, which actually checks against the full RFC spec (except for
nested comments), looks for addresses you may not wish to accept
mail to (say, Bill Clinton or your postmaster), and then makes sure
that the hostname given can be looked up in the DNS MX records.
It's not fast, but it works for what it tries to do.
Our best advice for verifying a person's mail address is to have
them enter their address twice, just as you normally do to change a
password. This usually weeds out typos. If both versions match,
send mail to that address with a personal message that looks
somewhat like:
Dear someuser@host.com,
Please confirm the mail address you gave us Wed May 6 09:38:41
MDT 1998 by replying to this message. Include the string
"Rumpelstiltskin" in that reply, but spelled in reverse; that is,
start with "Nik...". Once this is done, your confirmed address will
be entered into our records.
If you get the message back and they've followed your directions,
you can be reasonably assured that it's real.
A related strategy that's less open to forgery is to give them a
PIN (personal ID number). Record the address and PIN (best that it
be a random one) for later processing. In the mail you send, ask
them to include the PIN in their reply. But if it bounces, or the
message is included via a ``vacation'' script, it'll be there
anyway. So it's best to ask them to mail back a slight alteration
of the PIN, such as with the characters reversed, one added or
subtracted to each digit, etc.
How do I decode a MIME/BASE64 string?
The MIME-tools package (available from CPAN) handles this and a lot
more. Decoding BASE64 becomes as simple as:
use MIME::base64;
$decoded = decode_base64($encoded);
A more direct approach is to use the unpack() function's "u" format
after minor transliterations:
tr#A-Za-z0-9+/##cd; # remove non-base64 chars
tr#A-Za-z0-9+/# -_#; # convert to uuencoded format
$len = pack("c", 32 + 0.75*length); # compute length byte
print unpack("u", $len . $_); # uudecode and print
How do I return the user's mail address?
On systems that support getpwuid, the $< variable and the
Sys::Hostname module (which is part of the standard perl
distribution), you can probably try using something like this:
use Sys::Hostname;
$address = sprintf('%s@%s', getpwuid($<), hostname);
Company policies on mail address can mean that this generates
addresses that the company's mail system will not accept, so you
should ask for users' mail addresses when this matters.
Furthermore, not all systems on which Perl runs are so forthcoming
with this information as is Unix.
The Mail::Util module from CPAN (part of the MailTools package)
provides a mailaddress() function that tries to guess the mail
address of the user. It makes a more intelligent guess than the
code above, using information given when the module was installed,
but it could still be incorrect. Again, the best way is often just
to ask the user.
How do I send mail?
Use the `sendmail' program directly:
open(SENDMAIL, "|/usr/lib/sendmail -oi -t -odq")
or die "Can't fork for sendmail: $!\n";
print SENDMAIL <<"EOF";
From: User Originating Mail <me\@host>
To: Final Destination <you\@otherhost>
Subject: A relevant subject line
Body of the message goes here, in as many lines as you like.
EOF
close(SENDMAIL) or warn "sendmail didn't close nicely";
The -oi option prevents sendmail from interpreting a line
consisting of a single dot as "end of message". The -t option says
to use the headers to decide who to send the message to, and -odq
says to put the message into the queue. This last option means your
message won't be immediately delivered, so leave it out if you want
immediate delivery.
Or use the CPAN module Mail::Mailer:
use Mail::Mailer;
$mailer = Mail::Mailer->new();
$mailer->open({ From => $from_address,
To => $to_address,
Subject => $subject,
})
or die "Can't open: $!\n";
print $mailer $body;
$mailer->close();
The Mail::Internet module uses Net::SMTP which is less Unix-centric
than Mail::Mailer, but less reliable. Avoid raw SMTP commands.
There are many reasons to use a mail transport agent like sendmail.
These include queueing, MX records, and security.
How do I read mail?
Use the Mail::Folder module from CPAN (part of the MailFolder
package) or the Mail::Internet module from CPAN (also part of the
MailTools package).
# sending mail
use Mail::Internet;
use Mail::Header;
# say which mail host to use
$ENV{SMTPHOSTS} = 'mail.frii.com';
# create headers
$header = new Mail::Header;
$header->add('From', 'gnat@frii.com');
$header->add('Subject', 'Testing');
$header->add('To', 'gnat@frii.com');
# create body
$body = 'This is a test, ignore';
# create mail object
$mail = new Mail::Internet(undef, Header => $header, Body => \[$body]);
# send it
$mail->smtpsend or die;
Often a module is overkill, though. Here's a mail sorter.
#!/usr/bin/perl
# bysub1 - simple sort by subject
my(@msgs, @sub);
my $msgno = -1;
$/ = ''; # paragraph reads
while (<>) {
if (/^From/m) {
/^Subject:\s*(?:Re:\s*)*(.*)/mi;
$sub[++$msgno] = lc($1) || '';
}
$msgs[$msgno] .= $_;
}
for my $i (sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msgs)) {
print $msgs[$i];
}
Or more succinctly,
#!/usr/bin/perl -n00
# bysub2 - awkish sort-by-subject
BEGIN { $msgno = -1 }
$sub[++$msgno] = (/^Subject:\s*(?:Re:\s*)*(.*)/mi)[0] if /^From/m;
$msg[$msgno] .= $_;
END { print @msg[ sort { $sub[$a] cmp $sub[$b] || $a <=> $b } (0 .. $#msg) ] }
How do I find out my hostname/domainname/IP address?
The normal way to find your own hostname is to call the
``hostname`' program. While sometimes expedient, this has some
problems, such as not knowing whether you've got the canonical name
or not. It's one of those tradeoffs of convenience versus
portability.
The Sys::Hostname module (part of the standard perl distribution)
will give you the hostname after which you can find out the IP
address (assuming you have working DNS) with a gethostbyname()
call.
use Socket;
use Sys::Hostname;
my $host = hostname();
my $addr = inet_ntoa(scalar(gethostbyname($name)) || 'localhost');
Probably the simplest way to learn your DNS domain name is to grok
it out of /etc/resolv.conf, at least under Unix. Of course, this
assumes several things about your resolv.conf configuration,
including that it exists.
(We still need a good DNS domain name-learning method for non-Unix
systems.)
How do I fetch a news article or the active newsgroups?
Use the Net::NNTP or News::NNTPClient modules, both available from
CPAN. This can make tasks like fetching the newsgroup list as
simple as:
perl -MNews::NNTPClient
-e 'print News::NNTPClient->new->list("newsgroups")'
How do I fetch/put an FTP file?
LWP::Simple (available from CPAN) can fetch but not put. Net::FTP
(also available from CPAN) is more complex but can put as well as
fetch.
How can I do RPC in Perl?
A DCE::RPC module is being developed (but is not yet available),
and will be released as part of the DCE-Perl package (available
from CPAN). No ONC::RPC module is known.
AUTHOR AND COPYRIGHT
Copyright (c) 1997, 1998 Tom Christiansen and Nathan Torkington.
All rights reserved.
When included as part of the Standard Version of Perl, or as part
of its complete documentation whether printed or otherwise, this
work may be distributed only under the terms of Perl's Artistic
License. Any distribution of this file or derivatives thereof
*outside* of that package require that special arrangements be made
with copyright holder.
Irrespective of its distribution, all code examples in this file
are hereby placed into the public domain. You are permitted and
encouraged to use this code in your own programs for fun or for
profit as you see fit. A simple comment in the code giving credit
would be courteous but is not required.
------------------------------
Date: Wed, 05 Aug 1998 12:26:21 GMT
From: bob.p.lanteigne@mcdermott.com (Bob Lanteigne)
Subject: Re: Problem with $/ and \x0D on Win32
Message-Id: <35c84d58.3932180@trakker>
On Tue, 04 Aug 1998 15:21:17 -0400, Jim Michael <jim.michael@gecm.com>
wrote:
>Bob Lanteigne wrote:
>>
>> I'm using Perl on Win32 to process a file which has a line delimiter
>> of 0x0D, but I can't get it to work. This is what I've tried:
>
>Have you binmode the file?
>
>perldoc -f binmode
Jim,
Yes (well, now I have), and it does what I want. I discovered this
shortly *after* posting my earlier message. I guess this implies that
I can't use the 'while (<>) ...' construct for this program. I
changed my program to:
open(INFILE, ...) ...;
binmode(INFILE);
$/ = "\r";
while (<INFILE>) {
tr /\x0d/\x0d\x0a/;
...
}
Thanks,
Bob.
------------------------------
Date: 5 Aug 1998 12:33:56 GMT
From: Tom Christiansen <tchrist@mox.perl.com>
Subject: Re: Problems with File::Find
Message-Id: <6q9jfk$2ap$1@csnews.cs.colorado.edu>
[courtesy cc of this posting sent to cited author via email]
In comp.lang.perl.misc, mark-lists@webstylists.com (Mark Thompson) writes:
:Could anyone tell me where they got the version that I have? Is it from a
:version of File::Find that no longer exists?
The issue is that the Exporter does the wrong thing. You have to
import those yourself, using this
*name = *File::Find::name;
*dir = *File::Find::dir;
The *foo = \$P::v import won't work here. Why not is a long story.
--tom
--
"I can only bend the rules so much before it starts looking like I'm breaking
the rules." --Larry Wall
------------------------------
Date: Wed, 5 Aug 1998 12:22:04 GMT
From: Brent Michalski <perlguy@inlink.com>
Subject: Re: Problems with File::Find
Message-Id: <35C84E6C.BA5268A3@inlink.com>
With a little modification, this code should do what you are looking
for...
Notes:
1) I wrote and tested this on an NT box but it should work on a UNIX
box. (Don't flame me for using NT! I like UNIX better but the people
who sign my paychecks use NT.)
2) I left out the &PrintDirs subroutine. Mine was rather specialized
but all it needs to do is print out all the values in @dirs.
3) "if(-d $fullpath){ " checks to see if the current item is a
directory. Get rid of this if you want the files to be listed. Or
better yet, change it to "unless(-d $fullpath){" to SKIP the
subdirectories and only list files.
I hope this helps you out!
Brent
______________________________ CODE BELOW
________________________________
$start="j:/docs"; # Start at this subdirectory...
&GetDirs($start);
&PrintDirs;
exit;
sub GetDirs{
my $start=$_[0];
opendir(DIR,$start);
my(@filenames) = readdir(DIR);
close(DIR);
foreach $list (@filenames){
my $fullpath=$start."/".$list;
if(-d $fullpath){
if($list !~ /^(\.{1,2})$/){
push @dirs, $fullpath;
&GetDirs($fullpath); # Recursive call
}
}
}
} # End of sub GetDirs
------------------------------
Date: Wed, 05 Aug 1998 13:26:27 GMT
From: bart.mediamind@tornado.be (Bart Lateur)
Subject: Re: Suggestion: file handle associated $\
Message-Id: <35c95cab.644544@news.tornado.be>
John Porter wrote:
>so I think it would be trivial to simply modify (or derive from)
>FileHandle, so that objects of that class maintain their own data
>attributes for RS, ORS, and OFS, rather than using the perl special
>globals for those purposes.
Interesting approach. Is it possible to subclass the file handles so
that these overridden values get used instead the global equivalents?
I'm not experienced in OOPerl. Demo code that demonstrates this feature
would prove to me that OO in Perl is more than just a gimmick.
Any takers?
Bart.
------------------------------
Date: Wed, 05 Aug 1998 12:39:54 GMT
From: Rick Delaney <rick.delaney@shaw.wave.ca>
Subject: Re: unravelling (?=...), but what's the frog's motivation?
Message-Id: <35C85408.353A5DE4@shaw.wave.ca>
F.Quednau wrote:
>
>
> for (split /(?=(.*))/s , "Just another Perl Hacker\n") {print "$_\n"}
>
>
> Above program prints in its first line:
> J\n
> ust another Perl Hacker\n\n
>
> Apparently split used 'ust another Perl Hacker\n' as split expression.
> So the frog was just behind 'J' when the split occurred. It matches
> the whole thing following. But doesn't move. However, the next time he
> seems to be just behind 'u'. What is the frog's motivation :) ?
>
Split tells him to move forward, because it wants to match as many times
as possible. Compare what happens with:
for (split /(?=(.*))/s , "Just another Perl Hacker\n", 3) {print "$_\n"}
split acts a lot like the /g modifier. Try this also:
for ("Just another Perl Hacker\n" =~ m/(?=(.*))/gs) {print "$_\n"}
--
Rick Delaney
rick.delaney@shaw.wave.ca
------------------------------
Date: Wed, 05 Aug 1998 11:56:22 +0000
From: Adam Ipnarski <adam@fastfare.co.uk>
Subject: Re: wtf is the obsession with "foo" and "bar"
Message-Id: <35C84866.BFB08265@fastfare.co.uk>
Kim Saunders wrote:
>
> Hiya,
>
> Why are "foo" and "bar" ALWAYS used as example names in anything unix
> related, and partularly perl? What is the origin? What do they mean? (foo i
> can handle). Why aren't people more imaginative when they do stuff, and use
> their own things? It's rather irritating sometimes.
>
> KimS
Hi,
This is what I've heard.
Legend (over here in England, anyway) seems to suggest that foo and bar
stem from 'foobar'. This, in turn, is a nicer way of writing fubar,
which stands for 'F***ed up beyond all Recognition'.
As for why UNIX programmers use foo and bar, I suppose its because we
don't want to waste our imagination on unimportant things like temporary
var names :-)
PS. This newsgroup should not be used for pointless questions like this
one. If you *really* find it necessary to obtain answers to things like
this, use the Web. God knows there's wnough useless stuff out there!
--adam
Adam Ipnarski, Developer
adam@fastfare.co.uk | www.travelselect.com
------------------------------
Date: 5 Aug 1998 06:52:10 GMT
From: gebis@fee.ecn.purdue.edu (Michael J Gebis)
Subject: Re: wtf is the obsession with "foo" and "bar"
Message-Id: <6q8veq$agp@mozo.cc.purdue.edu>
"Kim Saunders" <kims@tip.net.au> writes:
}Why are "foo" and "bar" ALWAYS used as example names in anything unix
}related, and partularly perl? What is the origin? What do they mean? (foo i
}can handle). Why aren't people more imaginative when they do stuff, and use
}their own things? It's rather irritating sometimes.
When "Saving Private Ryan" comes to .au (if it isn't there already)
go see it. And when the nerdy guy keeps asking, "What's fubar mean,
anyway?" just keep on waiting. He finds out in the end (sorry, I
guess that's sort of a spoiler) at which point you too will find out.
--
Mike Gebis gebis@ecn.purdue.edu mgebis@eternal.net
------------------------------
Date: 12 Jul 98 21:33:47 GMT (Last modified)
From: Perl-Request@ruby.oce.orst.edu (Perl-Users-Digest Admin)
Subject: Special: Digest Administrivia (Last modified: 12 Mar 98)
Message-Id: <null>
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------------------------------
End of Perl-Users Digest V8 Issue 3362
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