[24598] in Perl-Users-Digest
Perl-Users Digest, Issue: 6774 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Jul 7 11:05:42 2004
Date: Wed, 7 Jul 2004 08:05:08 -0700 (PDT)
From: Perl-Users Digest <Perl-Users-Request@ruby.OCE.ORST.EDU>
To: Perl-Users@ruby.OCE.ORST.EDU (Perl-Users Digest)
Perl-Users Digest Wed, 7 Jul 2004 Volume: 10 Number: 6774
Today's topics:
Re: Auto die on failed sys calls? <krahnj@acm.org>
Re: console print issue <krahnj@acm.org>
Injecting variables after the import subroutine has bee (Daniel S.)
Re: Injecting variables after the import subroutine has <mritty@gmail.com>
Re: looping through IP address range <Eugene.Mikheyev@kiev.cms.com.ua>
Re: Math::BigFloat oddities (J. Romano)
Re: Newbie: How do I filter output to the screen and w <noreply@gunnar.cc>
Re: Newbie: How do I filter output to the screen and w <noreply@gunnar.cc>
Re: Perl and modems <mritty@gmail.com>
Perl IDEs <merman@snafu.de>
Re: Perl IDEs <mritty@gmail.com>
Re: Perl IDEs <bernard.el-haginDODGE_THIS@lido-tech.net>
Re: Perl IDEs <tadmc@augustmail.com>
problem with a script in perl. <NOTMe@ailleur.com>
Re: uninitialized? <matthew.garrish@sympatico.ca>
Re: Why is $ENV{COLUMNS} undefined inside the Perl prog <a24061@yahoo.munged>
Re: Why use dollar sign $ for variables <rene.nyffenegger@gmx.ch>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 07 Jul 2004 11:46:37 GMT
From: "John W. Krahn" <krahnj@acm.org>
Subject: Re: Auto die on failed sys calls?
Message-Id: <40EBE293.CB5490A6@acm.org>
J Krugman wrote:
>
> Is there any way to instruct perl to die whenever a system call
> (e.g. through open, opendir, backticks, system, etc.) fails?
>
> The aim is to be able to enclose a series of such calls in a single
> eval block, and catch any failures at the end, instead of checking
> for them after each system call.
perldoc Fatal
John
--
use Perl;
program
fulfillment
------------------------------
Date: Wed, 07 Jul 2004 11:49:44 GMT
From: "John W. Krahn" <krahnj@acm.org>
Subject: Re: console print issue
Message-Id: <40EBE34E.BAA7F595@acm.org>
Bigus wrote:
>
> "Eugene Mikheyev" <Eugene.Mikheyev@kiev.cms.com.ua> wrote in message
> news:ccegiv$2ek1$1@news.univ.kiev.ua...
> > > that should cause an angle bracket to be printed on the commandline
> every
> > 2
> > > seconds, but instead all 5 are printed at the same time when it's
> finished
> > > the loop. Can anyone shed any light on why?
> >
> > Sure, just turn on the autoflash.
> > $| = 1;
>
> that's odd, because I've never used $| before and in some of my previous
> scripts where I've looped through a folder of log files I've included a
> progress-bar style thing, like:
>
> >>>>>>>>>>>>>>>>>>>>>
> >>>>>
>
> where the first row of brackets is the number of log files and on the second
> row a bracket is printed after each file has been processed.. and it's
> worked fine. I guess something else must have forced a flush of teh print
> statements in those cases.
You could have been printing to STDERR which isn't buffered.
John
--
use Perl;
program
fulfillment
------------------------------
Date: 7 Jul 2004 07:13:26 -0700
From: lachinois@hotmail.com (Daniel S.)
Subject: Injecting variables after the import subroutine has been called?
Message-Id: <bdcf9711.0407070613.3852eb13@posting.google.com>
Hi!
I'm the author of the Regexp::Extended module and I'm trying to inject
variables into the main perl module (like the Exporter module does).
I'm using overload:constant to modify regexp expressions and there is
an extension for named groups (?<var>pattern). However, if I try to
export '$var' at the time overload:constant is being called (after the
import sub has been executed) all I get is a segfault.
Is there a way of exporting variables during the execution of a perl
code short of using $::var?
Thanks for any help, no matter how complex or obscure.
Daniel S.
------------------------------
Date: Wed, 7 Jul 2004 10:31:45 -0400
From: Paul Lalli <mritty@gmail.com>
Subject: Re: Injecting variables after the import subroutine has been called?
Message-Id: <20040707102738.N22150@barbara.cs.rpi.edu>
On Wed, 7 Jul 2004, Daniel S. wrote:
> Hi!
>
> I'm the author of the Regexp::Extended module and I'm trying to inject
> variables into the main perl module (like the Exporter module does).
>
> I'm using overload:constant to modify regexp expressions and there is
> an extension for named groups (?<var>pattern). However, if I try to
> export '$var' at the time overload:constant is being called (after the
> import sub has been executed) all I get is a segfault.
>
> Is there a way of exporting variables during the execution of a perl
> code short of using $::var?
Er, is there a reason you can't just use the import function in your main
code?
#!/usr/bin/perl
use strict;
use warnings;
use MyMod('$foo');
print "Module's foo value: $foo\n";
import MyMod ('$bar');
print "Module's bar value: $bar\n";
__END__
Of course, MyMod in this case would still have to have $bar in it's
@EXPORT_OK array.
'use' is nothing more than a call to require and import wrapped in a
BEGIN{} block.
Paul Lalli
------------------------------
Date: Wed, 7 Jul 2004 14:20:19 +0300
From: "Eugene Mikheyev" <Eugene.Mikheyev@kiev.cms.com.ua>
Subject: Re: looping through IP address range
Message-Id: <ccgmbn$d93$1@news.univ.kiev.ua>
use strict;
use Benchmark;
timethese(
10000,
{
Join1 => sub {
my @parts = (10, 10, 10);
for my $last_part (0..255) {
my $ip = join '.', @parts, $last_part;
do_something( $ip );
}
},
Join2 => sub {
my @parts = (10, 10, 10);
for (my $last_part = 0; $last_part <= 255; $last_part++) {
do_something(join '.', @parts, $last_part);
}
},
Join3 => sub {
for my $last_part (0 .. 255) {
do_something("10.10.10.$last_part");
}
},
Exp1 => sub {
for my $ip ( map "10.10.10.$_", 0 .. 255 ) {
do_something( $ip );
}
},
Exp2 => sub {
map do_something("10.10.10.$_"), 0 .. 255
}
}
);
sub do_something {
my $myvar = shift;
}
Results:
------------
Benchmark: timing 10000 iterations of Exp1, Exp2, Join1, Join2, Join3...
Exp1: 5 wallclock secs ( 5.17 usr + 0.00 sys = 5.17 CPU) @
1933.49/s (n=10000)
Exp2: 5 wallclock secs ( 4.75 usr + 0.00 sys = 4.75 CPU) @
2105.26/s (n=10000)
Join1: 6 wallclock secs ( 5.19 usr + 0.00 sys = 5.19 CPU) @
1927.53/s (n=10000)
Join2: 4 wallclock secs ( 4.28 usr + 0.00 sys = 4.28 CPU) @
2335.90/s (n=10000)
Join3: 3 wallclock secs ( 2.88 usr + 0.00 sys = 2.88 CPU) @
3478.26/s (n=10000)
Join3 results show that interpolating and then looping is worse than just
looping and interpolating :)
I bet that's because of foreach cycle.
Strange why Exp2 is worse than Join3... But maybe that's because map needs
to create a list for output.
------------------------------
Date: 7 Jul 2004 07:09:00 -0700
From: jl_post@hotmail.com (J. Romano)
Subject: Re: Math::BigFloat oddities
Message-Id: <b893f5d4.0407070608.3002f3cc@posting.google.com>
jl_post@hotmail.com (J. Romano) wrote in message news:<b893f5d4.0407061706.64cca68e@posting.google.com>...
>
> Using the '-=' operator on a Math::BigInt object calls the bsub()
> method, which subtracts two Math::BigInt objects by doing the
> following:
>
> 1. It flips the sign of the second object (to negate it)
> 2. It adds the two objects together (with the badd() method)
> 3. It flips the sign of the second object again (to restore it)
Let me clarify a bit here. Suppose we had two Math::BigInt
variables:
my $a = Math::BigInt->new(5); # $a equals 5
my $b = Math::BigInt->new(1); # $b equals 1
and we used them together with the '-=' operator, like this:
$a -= $b;
The '-=' operator basically does the following three steps:
1. It temporarily negates $b:
$b = -$b; # $b is now -1
2. It adds $a and $b and puts the result in $a:
$a = $a + $b; # same as: $a = 5 + -1 (which equals 4)
3. It negates $b again to restore its original sign:
$b = -$b; # $b is now back to 1
If $x was declared with a line like:
my $x = Math::BigInt->new(3); # $x equals 3
You can see why the operator '-=' messes up with a line like:
$x -= $x;
by applying the same three steps to $x:
1. It temporarily negates $x:
$x = -$x; # $x is now -3
2. It adds $x and $x and puts the result in $x:
$x = $x + $x; # same as: $x = -3 + -3 (which equals -6)
3. It negates $x again to restore its original sign:
$x = -$x; # $x is now 6 (not zero)!
If you understood that, this should make more sense now:
> Apparently the bsub() method assumes that the first and second object
> are NOT the same. But since they are, when steps 1 and 3 get carried
> out, both the first object AND the second object get their sign
> flipped.
A better fix than the one I suggested last time would be to give
the second object a copy of the first if it's found that they are both
references to the same object:
if (overload::StrVal($x) eq overload::StrVal($y))
{
# The first and second objects are the same,
# so give the second a copy of the first:
$y = Math::BigInt->new($x);
}
This fix should go in the Math::BigInt::bsub() method right before the
sign of $y is flipped. Unlike the previous fix I suggested, this fix
should be able to handle NaN values. It might use a little more
overhead (by creating a new copy of a Math::BigInt), but that's fairly
negligible due to the fact that a line like "$x -= $x" rarely ever
gets called.
So that's the reason for the bug with the '-=' operator in
Math::BigInt. I'm not sure if Math::BigFloat inherits the same bug,
or if it's a different one altogether. Either way, I hope this clears
up some confusion (and some bugs!).
-- Jean-Luc Romano
------------------------------
Date: Wed, 07 Jul 2004 14:58:09 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: Newbie: How do I filter output to the screen and writing the orginal output to a file?
Message-Id: <2l2b6vF7qbtbU1@uni-berlin.de>
Anno Siegel wrote:
> Backticks and qx wait until the background process is finished and
> deliver all the output at once. To see the lines of output as they
> appear, open a filehandle to capture the output. Untested:
>
> open my $proc, "@args |";
> /^(\s*--.+)/ and print "$1\n" while <$proc>;
Thanks, Anno!
So, then a solution to the OP's question may be:
open my $log, '>> build.log' or die $!;
open my $proc, "@args |" or die $!;
while (<$proc>) {
print $log $_;
print if /^(\s*--.+)/;
}
close $proc;
close $log;
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Wed, 07 Jul 2004 15:17:22 +0200
From: Gunnar Hjalmarsson <noreply@gunnar.cc>
Subject: Re: Newbie: How do I filter output to the screen and writing the orginal output to a file?
Message-Id: <2l2cb4F7qappU1@uni-berlin.de>
Gunnar Hjalmarsson wrote:
>
> print if /^(\s*--.+)/;
That can obviously be shortened to:
print if /^\s*--/;
--
Gunnar Hjalmarsson
Email: http://www.gunnar.cc/cgi-bin/contact.pl
------------------------------
Date: Wed, 7 Jul 2004 09:34:52 -0400
From: Paul Lalli <mritty@gmail.com>
Subject: Re: Perl and modems
Message-Id: <20040707093217.F22150@barbara.cs.rpi.edu>
On Wed, 7 Jul 2004, timgerr wrote:
> I want to write a script that will send information to the modem to
> automate a phone queue that I have to call every say. I heard that this
> can be done in perl but I am net to perl. Can someone point me in a
> direction?
How new to Perl are you? If you need to learn the basics, I point you to
http://learn.perl.org
If you are comfortable with the language, I point you to CPAN. This is
the place you go when you wonder "Has anyone already done ____" in Perl?
You start your search of CPAN at http://search.cpan.org.
In this case, a search for "Modem" turned up this likely candidate:
http://search.cpan.org/~cosimo/Device-Modem-1.36/docs/Modem.pod
Paul Lalli
------------------------------
Date: Wed, 07 Jul 2004 15:20:18 +0200
From: Thomas Kaufmann <merman@snafu.de>
Subject: Perl IDEs
Message-Id: <40EBF892.3060206@snafu.de>
Hi there,
I'm a Perl-Newbie and I looking for good and modern Perl-IDEs. Can you help me?
o-o
Thomas
------------------------------
Date: Wed, 7 Jul 2004 09:13:15 -0400
From: Paul Lalli <mritty@gmail.com>
Subject: Re: Perl IDEs
Message-Id: <20040707091226.Y22150@barbara.cs.rpi.edu>
On Wed, 7 Jul 2004, Thomas Kaufmann wrote:
> Hi there,
>
> I'm a Perl-Newbie and I looking for good and modern Perl-IDEs. Can you help me?
This topic has been covered about 4 times in the past 2 months of this
group. Go to groups.google.com, and search the archives of this group for
"IDE" or "editor".
Paul Lalli
------------------------------
Date: Wed, 7 Jul 2004 15:14:06 +0200
From: "Bernard El-Hagin" <bernard.el-haginDODGE_THIS@lido-tech.net>
Subject: Re: Perl IDEs
Message-Id: <Xns951F9B54EE7CCelhber1lidotechnet@62.89.127.66>
Thomas Kaufmann <merman@snafu.de> wrote:
> Hi there,
>
> I'm a Perl-Newbie and I looking for good and modern Perl-IDEs. Can
> you help me?
Console + screen + vim. Oh wait, you said modern. xterm + screen + vim.
--
Cheers,
Bernard
------------------------------
Date: Wed, 7 Jul 2004 09:25:33 -0500
From: Tad McClellan <tadmc@augustmail.com>
Subject: Re: Perl IDEs
Message-Id: <slrnceo1ut.31f.tadmc@magna.augustmail.com>
Thomas Kaufmann <merman@snafu.de> wrote:
> I'm a Perl-Newbie
Please check the Perl FAQ *before* posting to the Perl newsgroup.
> and I looking for good and modern Perl-IDEs. Can you help me?
perldoc -q IDE
Is there an IDE or Windows Perl Editor?
--
Tad McClellan SGML consulting
tadmc@augustmail.com Perl programming
Fort Worth, Texas
------------------------------
Date: Wed, 7 Jul 2004 13:21:51 +0200
From: "Andre" <NOTMe@ailleur.com>
Subject: problem with a script in perl.
Message-Id: <ccgm55$eur$1@bemesrrs011.be.eds.com>
Hello,
not too sure if this is a perl 5.8 or a sendmail (8.12.9).
I have made a script that extract, and save the attachment. I work well but.
if a line, in the attachemant is longer than 139 characteres, the complet
output is screwed with line of differnet lenght, containing aditionnal
characters (like "=" ) even outside the attachment.
a loop like
LOG="/tmp/mail";
while (<>) {
print LOG $_;
}
contains the errors if the attachemnt contains long lines.
Any idea ??
Many thanks in advances.
Andre
------------------------------
Date: Wed, 7 Jul 2004 09:41:13 -0400
From: "Matt Garrish" <matthew.garrish@sympatico.ca>
Subject: Re: uninitialized?
Message-Id: <Y3TGc.38455$JG5.743020@news20.bellglobal.com>
"Paul Lalli" <mritty@gmail.com> wrote in message
news:20040706223018.V22150@barbara.cs.rpi.edu...
> On Tue, 6 Jul 2004, Matt Garrish wrote:
>
> > "Ken Sington" <ken_sington@nospam_abcdefg.com> wrote in message
> > news:EuudnYiVgJi-xXbdRVn_iw@speakeasy.net...
> > > uninitialized? Isn't it already?
> > >
> > > #!/usr/bin/perl -T
> > >
> > > use warnings;
> > > use strict;
> > >
> > > my $a=1;
> > >
> > > unless ($a eq undef|| $a eq 0){
> > > print "\$a = $a\n";
> > > }
> > >
> > >
> >
> > Because "undef" is a bareword
>
> No it's not. No more than print or push or pop are barewords.
>
D'oh! I meant function. Barewords don't cause undefined errors, of course...
: )
Matt
------------------------------
Date: Wed, 07 Jul 2004 13:50:24 GMT
From: Adam <a24061@yahoo.munged>
Subject: Re: Why is $ENV{COLUMNS} undefined inside the Perl program?
Message-Id: <AcTGc.200$zG7.2039977@news-text.cableinet.net>
On Monday 05 July 2004 12:55, Joe Smith wrote:
> You can catch errors using eval{}.
>
> use Term::ReadKey;
> my ($wchar, $hchar, $wpixels, $hpixels);
> eval { ($wchar, $hchar, $wpixels, $hpixels) = GetTerminalSize() };
> if (defined $wchar) {
> print "Width and height = $wchar, $hchar\n";
> } else {
> print "Terminal size is undefined\n";
> }
Thanks! I'd forgotten about using eval for error-catching.
------------------------------
Date: 7 Jul 2004 11:06:55 GMT
From: Rene Nyffenegger <rene.nyffenegger@gmx.ch>
Subject: Re: Why use dollar sign $ for variables
Message-Id: <slrncenm0j.3lk.rene.nyffenegger@zhnt60m34.netarchitects.com>
> Unlike /bin/sh, bash, tcsh, etc, perl does not interpret (parse and
> execute) the script a line at a time as you implied.
>
> In the absence of any 'use' statements or BEGIN{} blocks, perl parses
> the entire program before executing any code. It does this every time
> the perl script is invoked, vaguely like an interpreter, but perl
> definitely has a compile phase and a run phase.
> -Joe
Just out of curiosity: would it be possible to store the compiled/parsed
script away and load it later so that a script doesn't have to be
compiled again if it hasn't changed?
Rene
--
Rene Nyffenegger
http://www.adp-gmbh.ch/
------------------------------
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 6774
***************************************
