[26704] in Perl-Users-Digest
Perl-Users Digest, Issue: 8804 Volume: 10
daemon@ATHENA.MIT.EDU (Perl-Users Digest)
Wed Dec 28 11:05:28 2005
Date: Wed, 28 Dec 2005 08:05:05 -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 Wed, 28 Dec 2005 Volume: 10 Number: 8804
Today's topics:
"local @_ = @_;" for "pass-by-value"? <issakov@t-online.de>
'file changed'-event <news2132@8439.e4ward.com>
grep: \" and " both Give Errors <wh2leung@student.cs.uwaterloo.ca>
Re: How to print (2 & (1 * (2**32)))? <rvtol+news@isolution.nl>
Digest Administrivia (Last modified: 6 Apr 01) (Perl-Users-Digest Admin)
----------------------------------------------------------------------
Date: Wed, 28 Dec 2005 14:10:51 +0100
From: Mihail <issakov@t-online.de>
Subject: "local @_ = @_;" for "pass-by-value"?
Message-Id: <dou2ss$497$01$1@news.t-online.com>
Hello,
again about sub{} behavior and "pass-by-call"/"pass-by-value".
Is it clean and recommended to use local @_ ?
sub {
local @_ = @_;
...
}
I do not like the way of fantasy arrays:
sub {
my @pass_by_value_workaround = @_;
...
}
It is ugly. But i still don't see clear advice how to do
"call-by-value"? And "local" things seems to change from
version to version.
Thank you.
Mihail
------------------------------
Date: Wed, 28 Dec 2005 16:57:43 +0100
From: Michael Goerz <news2132@8439.e4ward.com>
Subject: 'file changed'-event
Message-Id: <41fqvnF1c3e1gU1@uni-berlin.de>
Hi,
I'm trying to execute a sub whenever a certain file on the disk changes.
Currently, I'm doing this with an infinite loop that checks the modify
time (stat("$file"))[9]. While this works in principle, the infinite
loop drives the CPU crazy and speeds up the fan (very annoying).
Can I implement this with an event-based approach that doesn't drive up
my CPU? How?
Thanks,
Michael Goerz
------------------------------
Date: Wed, 28 Dec 2005 09:52:37 -0500
From: William <wh2leung@student.cs.uwaterloo.ca>
Subject: grep: \" and " both Give Errors
Message-Id: <Pine.GSO.4.64.0512280930540.29304@cpu02.student.cs.uwaterloo.ca>
In my perl script, I currently have:
#!/usr/bin/perl -w
use strict;
my $InputFileDir = "/mkapp/webapps/mxrt-cgi/upload_vol/upload_files/";
my $savedfilename = "trs_vol.txt.49.22.224.163.VERGAJ2.20050215.10.21.21";
my $filename = "trs_vol.txt";
my $originalList = $InputFileDir . $savedfilename;
my $originalListBack = $InputFileDir . $filename;
system "sed -e 's/^M//' $originalList | grep \"USD FNM\" > $originalListBack";
where $originalList is a file that contains:
|USD CHL|USD NYSE|Securities|1d|0|ATM|16.3194164633751|16.3194164633751|
|USD CHL|USD NYSE|Securities|3d|0|ATM|16.3215860724449|16.3215860724449|
|USD CHL|USD NYSE|Securities|1w|0|ATM|16.3243487477303|16.3243487477303|
|USD CHL|USD NYSE|Securities|2w|0|ATM|16.3260638713837|16.3260638713837|
|USD CHL|USD NYSE|Securities|3w|0|ATM|16.3272082805634|16.3272082805634|
|USD CHL|USD NYSE|Securities|1m|0|ATM|16.3357391953468|16.3357391953468|
|USD CHL|USD NYSE|Securities|3m|0|ATM|17.0192211866379|17.0192211866379|
|USD CHL|USD NYSE|Securities|4m|0|ATM|17.4577638506889|17.4577638506889|
|USD CHL|USD NYSE|Securities|6m|0|ATM|17.9224327206612|17.9224327206612|
|USD CHL|USD NYSE|Securities|9m|0|ATM|18.4148281812668|18.4148281812668|
$originalListBack is an (uncreated) file named trs_vol.txt
My problem: $originalListBack is not being created by this line:
system "sed -e 's/^M//' $originalList | grep \"USD FNM\" > $originalListBack";
I tried the following on the command line:
sed -e 's/^M//' trs_vol.txt.49.22.224.132.LEUNGW5.20051227.16.36.13 | grep
\"USD FNM\" > trs_vol.txt
but I got the following error message:
grep: can't open FNM"
Broken Pipe
However, if I try the following line on the command line, I got a 0 KB
trs_vol.txt file, which is what I desire.
sed -e 's/^M//' trs_vol.txt.49.22.224.132.LEUNGW5.20051227.16.36.13 | grep
"USD FNM" > trs_vol.txt
But if I remove the \ from the system "sed ..." line, then my Perl script
does not compile.
My question: what is the correct way to obtain a 0 KB trs_vol.txt file
using Perl (not command line)?
------------------------------
Date: Wed, 28 Dec 2005 14:32:57 +0100
From: "Dr.Ruud" <rvtol+news@isolution.nl>
Subject: Re: How to print (2 & (1 * (2**32)))?
Message-Id: <dou7mu.1es.1@news.isolution.nl>
sonet schreef:
> print (2 & (1 * (2**32)));
>
> The result is 2 ??
perl -le 'print("2 & 2**", $_, ":\t", 2&2**$_)
for map(2**$_, 0..10)'
--
Affijn, Ruud
"Gewoon is een tijger."
------------------------------
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 8804
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