Re: Scalar References - oxymoron?
On Mon, 03 Apr 2017 15:52:59 -0700, SSC_perl wrote: > Reading http://perldoc.perl.org/perlreftut.html I see it’s possible to > create a scalar reference. What situation would require someone to > create a reference to a scalar? I thought refs were only useful for > passing complex data structures. Is it just because Perl lets you, or > is there a reason I’m not aware of? It seems like it would just be > redundant. They can make handy objects, whivh have to be references, but if you're making an inside-out object which doesn't contain its own attributes, you want something light and immutable. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=9780133036268 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: grep - block with start & end text
Thanks Andrew. Your article explained what I did not have the words for. It was very well written. Scott On Fri, Mar 18, 2016 at 1:23 PM Andrew Solomon <and...@geekuni.com> wrote: > And to understand Scott's easy to write, hard to understand approach: > > http://blog.geekuni.com/2016/03/perl-flip-flop.html > > Andrew > > On Fri, Mar 18, 2016 at 3:50 PM, Scott Hall <banshee@gmail.com> wrote: > >> >> >> On Fri, Mar 18, 2016 at 9:40 AM Prashant Thorat < >> thorat.prash...@gmail.com> wrote: >> >>> Hi All, >>> >>> Can you please help me to grep below 'block of text' from my file ? this >>> blocks occurs number of time & I want to grep all in between lines of this >>> block - >>> >>> first line is having - retr_test asm1 >>> & 4th line is having only - END >>> >>> so I want to grep all four lines with above match . >>> >>> >> If you are looking for a command line that works like grep: >> >> perl -lne 'print if /retr_test asm1/ .. /END/;' input_file >> >> http://perldoc.perl.org/perlop.html#Range-Operators >> >> Best Regards, >> >> Scott >> >> >>> Thanks in advance, >>> Prashant >>> >>> >>> > > > -- > Andrew Solomon > > Mentor@Geekuni http://geekuni.com/ > http://www.linkedin.com/in/asolomon >
Re: grep - block with start & end text
On Fri, Mar 18, 2016 at 9:40 AM Prashant Thorat <thorat.prash...@gmail.com> wrote: > Hi All, > > Can you please help me to grep below 'block of text' from my file ? this > blocks occurs number of time & I want to grep all in between lines of this > block - > > first line is having - retr_test asm1 > & 4th line is having only - END > > so I want to grep all four lines with above match . > > If you are looking for a command line that works like grep: perl -lne 'print if /retr_test asm1/ .. /END/;' input_file http://perldoc.perl.org/perlop.html#Range-Operators Best Regards, Scott > Thanks in advance, > Prashant > > >
Re: Forking as another user
On Sat, 12 Mar 2016 18:44:18 +0200, Lars Noodén wrote: > The snippet below works to fork as a specific user, if run as root. > However, it generates zombies. The functions wait() or waitpid() seem > to be available to use to stop that, but if I insert either of them in > the outer while loop, only one client can connect at a time. > > What modification can prevent zombies yet allow multiple concurrent > clients to attach? You need the WNOHANG option on your wait() to make it nonblocking. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=9780133036268 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Operand evaluation order
On Fri, 14 Mar 2014 13:03:58 -0400, Ralph Grove wrote: I'm trying to determine how Perl evaluates operands for expressions. I expected the following code to output 3, 4, and 5, as it would if executed as a C++ or Java program. The actual output that I get (v5.16.2), however, is 4, 4, and 5. This leads me to believe that operand evaluation is either non-deterministic and compiler-dependent, or it's simply broken. Kudos for the curiosity. Did you have any other reason for wanting to know how this worked in Perl? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.oreillyschool.com/certificates/perl-programming.php http://www.informit.com/store/product.aspx?isbn=9780133036268 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: question about perl 6 sigils
On Tue, 24 Sep 2013 18:48:40 +0200, Luca Ferrari wrote: I read both the book and the exegenis, it is only that it requires me to think about the correct usage of sigils because it is not as much intuitive for me as it is in v5. I was just trying to explain to my brain why having immutable sigils is smarter than the v5 ones. I know Perl is built in a way everything has a strong sense, I cannot see what is in this case. When you learn a language - Perl 5 in this case - its syntax becomes 'intuitive'. From then on, any deviation from it is unintuitive. It takes a special kind of genius to be both familiar with that language and step outside of it to determine what will be more intuitive to someone who has not encountered the language at all yet, and that's what we have in Larry and Damian. In my classes, people invariably wanted to put @ on the beginning of an array element to begin with. After enough correction, they learned to use $, and adopted the rationalization for it. But most people's first instinct is @. That's why the Llama book doesn't introduce the @ sign for arrays until after its shown the use of $ for scalar elements. Damian and Larry determined that they could remove this small speed bump without any damage to the language. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.oreillyschool.com/certificates/perl-programming.php http://www.informit.com/store/product.aspx?isbn=9780133036268 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Who instantiated an object
On Fri, 31 May 2013 13:13:29 +, Weidner, Ron wrote: my ( $proto, $common, $name, $options ) = @_; my $class = ref($proto) || $proto; That is a common bit of cargo-culting that you might want to rethink. I know it's posted all over the place but it's generally considered a bad practice now. See http://search.cpan.org/~petdance/Perl-Critic-Bangs-1.08/lib/Perl/Critic/ Policy/Bangs/ProhibitRefProtoOrProto.pm and near the end of http:// www.stonehenge.com/merlyn/UnixReview/col52.html. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.oreillyschool.com/certificates/perl-programming.php http://www.informit.com/store/product.aspx?isbn=9780133036268 http://www.oscon.com/oscon2013/public/schedule/detail/28923 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: hash issue
On Wed, 17 Apr 2013 11:47:49 -0700, Jim Gibson wrote: 1. You should not modify a hash while you are iterating through it with the each() function. The each() function uses an internal data structure that persists from one call of each to the next. That internal data structure can be modified if you add or delete elements (as you are doing). So the documentation has warned. Yet it should probably be updated, since that behavior has been demonstrated to be safe: https://groups.google.com/ forum/?hl=enfromgroups#!topic/comp.lang.perl.misc/53Lfj8IM0JQ and there is specific code in the internals to make it safe: https:// groups.google.com/forum/?hl=enfromgroups=#!topic/comp.lang.perl.moderated/ _J9aO8pdAVc -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Proposed correction for my long script
On Sun, 16 Sep 2012 12:46:08 -0700, jmrhide-perl wrote:
Does it look OK?
This is a prime example of something that a test harness would be very
useful for, then we'd all know the answer.
There may be some entirely different reason why your provider thinks this
script is consuming excessive resources. They may be wrong. Having some
idea of how long it takes to execute would be good:
END {
my $elapsed = time - $^T;
send_mail We took $elapsed seconds to run at . localtime . !
if $elapsed $MAX_PERMISSIBLE_RUN_TIME;
}
If all else fails, install your own timeout:
alarm $MAX_PERMISSIBLE_RUN_TIME;
$SIG{ALRM} = sub { die Exceeded $MAX_PERMISSIBLE_RUN_TIME timeout };
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Re: My script is OUT OF CONTROL!
Set up some test harnesses to run from the command line so you can see how your script behaves without having to run it through a web server. Since it gets its input from a cookie, set the environment variable HTTP_COOKIE to each test value in turn and execute the script. (You'll get a mess of HTML back that'll be tedious to validate. This is the point at which you learn about separation of responsibilities and the Model-View-Controller pattern if you want to improve how you do this in the future.) -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Using different libraries dynamically
On Wed, 12 Sep 2012 10:18:49 -0400, Mark Haney wrote:
I've got what I hope is an easy question to answer. I've got a perl web
app that I've setup with a 'live' version (more like a beta actually)
and a dev version for me to make changes to that might break the other
site.
The way I inherited it was as a single site using 'use lib' with the
library files to a working site being used as the dev version. I've
moved the files around to match the first paragraph setup. Two
different sets of files, one live the other development.
For the time being I've manually change the 'use lib' statement before
uploading the changed/fixed code to the live site, but this is getting a
bit silly, not to mention completely not standard practice.
My question is, what IS standard practice for this? Honestly, I've
never built a web app in this manner despite writing a lot of perl code.
So? What should I do? Any suggestions are appreciated.
If the dev site and live site are on different filesystems and each
doesn't share the other's path, then just put both directories in the use
lib argument. That's a bit fragile, though, because one day they might
both exist on the same system.
What I do is have a module that figures out whether I'm in dev or prod; I
use it before the use lib and get a value back that I can use to switch
which path to fetch. Something like (pseudo code, untested):
use MyEnv; # Sets $MyEnv::Env_Type
BEGIN {
require lib;
lib-import( $MyEnv::Env eq 'dev' ? '/path/to/dev' : '/path/to/prod' );
}
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Re: parsing multiple logins logs (create a unique hash name for every user)
On Mon, 10 Sep 2012 20:52:41 +0800, andrew sison wrote:
I don't get how you can actually print the contents of the subhash.
Generic hash-of-hashes iteration example:
for my $outer_key ( keys %hash )
{
print Outer key: $outer_key:\n;
for my $inner_key ( sort keys %{ $hash{$outer_key} } )
{
print \t$inner_key: $hash{$outer_key}{$inner_key}\n;
}
}
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Re: Perl Code
On 2012-08-29, at 12:46 PM, Ashwin Rao T ashwin...@gmail.com wrote:
1)Check if IP address is in the range 172.125.1.0 and 172.125.25.0
using only return functions regular expressions in Perl.
/\b172\.125\.(\d+)\.((?\d+))(??{(1=$1 $1=24 0=$2 $2=255)||
($1==25 $2==0) ? : (*FAIL)})/ and say Strictly correct answer
that shows instructor didn't think about the question
Do let us know what grade that gets you :-)
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Re: Perl Code
On Sat, 01 Sep 2012 04:05:31 +, Peter Scott wrote:
On 2012-08-29, at 12:46 PM, Ashwin Rao T ashwin...@gmail.com wrote:
1)Check if IP address is in the range 172.125.1.0 and 172.125.25.0
using only return functions regular expressions in Perl.
/\b172\.125\.(\d+)\.((?\d+))(??{(1=$1 $1=24 0=$2 $2=255)||
($1==25 $2==0) ? : (*FAIL)})/ and say Strictly correct answer
that shows instructor didn't think about the question
Do let us know what grade that gets you :-)
Forgot the /a...
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Re: Attach iCal event to an cgi mail
After your program has opened SENDMAIL, open it again in the debugger to wherever you want (e.g., open SENDMAIL, 'STDOUT'). Since it's a bareword filehandle, you'll be reopening the same one. On Thu, 07 Jun 2012 12:59:20 -0700, mstep wrote: Yes the Filehandle is opened for writing. Is there any means to look inside? How to redirect the content of SENDMAIL in the debugger? Am Donnerstag, 7. Juni 2012 06:19:43 UTC+2 schrieb Peter Scott: On Mon, 04 Jun 2012 10:37:35 -0700, Marek wrote: Could somebody please tell me, how can I see into a FILEHANDLE in Perl debugger? I tried with x SENDMAIL but I get only empty array. That filehandle is open for *output* in your program! What is it you want to examine? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-cgi-unsubscr...@perl.org For additional commands, e-mail: beginners-cgi-h...@perl.org http://learn.perl.org/
Re: Attach iCal event to an cgi mail
On Mon, 04 Jun 2012 10:37:35 -0700, Marek wrote: Could somebody please tell me, how can I see into a FILEHANDLE in Perl debugger? I tried with x SENDMAIL but I get only empty array. That filehandle is open for *output* in your program! What is it you want to examine? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-cgi-unsubscr...@perl.org For additional commands, e-mail: beginners-cgi-h...@perl.org http://learn.perl.org/
Re: Unblessed reference problem
On Sun, 20 May 2012 18:28:10 +0300, Shlomi Fish wrote: Note that I think I saw a way to return the flattened array in Moose, but I don't remember the specifics. auto_deref = 1 -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How Can I find all kinds of methods a Object support?
On Wed, 11 Apr 2012 16:12:22 +0800, Zapp wrote: How Can I find all kinds of methods a Object support? For example: my $fh = IO::File-new(/path/to/file); how manny kinds of methods does the $fh have ? I try perldoc IO::File , but didn't find what I want. I suspect that what you want is documentation, because a literal answer to your question will only give a list of method names, which is rarely useful (I've used it on occasion for very specialized classes where that list constituted metadata of a sort.) As Lesley said, if you don't find the methods you're looking for in the class itself, try superclasses. This is one case where the structured nature of documentation in more rigid languages has an edge over Perl. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Using the ternary operator to concat a string not working like I think?
On Wed, 04 Apr 2012 03:04:42 -0400, Uri Guttman wrote:
On 04/03/2012 06:55 PM, timothy adigun wrote:
that is the wrong way to fix this even if it works.
the ternary operator is meant to return a single value from a choice of
two expressions. it is not meant for side effects like assignment or sub
calls that do things. use if/else for that. the correct answer here is
to use if/else as the assignments go to different places.
if( $test{one} eq 'first' ) {
$test{one} .= is the worst\n ;
else {
$test{two} .= is the best\n;
}
that code is not a good use of ?: at all so use if/else.
Right. And if you want the single statement succinctness, use and/or:
% perl -le '%test = qw(one first two second); $test{one} eq first and
$test{one} .= is the worst or $test{two} .= is the best; print for
values %test'
first is the worst
second
% perl -le '%test = qw(one third two second); $test{one} eq first and
$test{one} .= is the worst or $test{two} .= is the best; print for
values %test'
third
second is the best
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Re: Why do I get a warning?
On Thu, 22 Mar 2012 20:06:35 -0400, Uri Guttman wrote: no one uses braces for single scalar handles in general. I do. Ever since Damian recommended it (Perl Best Practices, page 217). One of those numerous times I didn't agree with him until I tried it, then found he was right. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Transitioning from BASH to Perl
On Sat, 17 Mar 2012 02:43:02 +0530, Deepak Malhotra wrote: You might have got similar questions in past too but could I request to demystify it again on how to swiftly and quickly make transition to Perl from Bash. Although I am no expert of Bash and awk but I can do the stuff which suffice my needs. What I am really looking for is the text processing (grep , awk, tr), conditional statements and control structures, to automate my work and create scripts (Garbage-in Garbage-out types) Please guide on how to learn minimal perl quickly. Any tutorials/books which deals with this kind of approach? Tim Maher's Minimal Perl was designed for your kind of requirement: http://www.amazon.com/Minimal-Perl-UNIX-Linux-People/dp/1932394508 . -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: run command from perl
On Fri, 02 Mar 2012 21:31:50 +0100, Manfred Lotz wrote: Another question I have: Where do I find what '-|' means? I mean the minus before the pipe char. perldoc -f open -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: run command from perl
On Sun, 26 Feb 2012 20:30:56 +0100, Manfred Lotz wrote:
I want to run a shell command with the following constraints:
a. I like to get the return code of the command b. Furthermore I want to
combine stdout and stderr so that the output comes in a natural sequence
like in the shell. c. I don't want to capture the output in a variable
(because the output could be really large and I don't want to wait for
the first line of output)
I did this:
use IPC::Open3;
sub run_cmd {
my $cmd = shift @_;
my $pid = open3(undef, *CMD_OUT, *CMD_OUT,$cmd);
while ( CMD_OUT) { print $_; }
waitpid($pid,0);
my $rc = $? 8;
return $rc;
}
I tested the code and it I can say it worked fine under fair weather
conditions.
Question: Is the code ok, or could it be improved, or has it even flaws?
It doesn't have flaws. You could do it without the module with a piped
open:
sub run_cmd
{
my $cmd = shift;
open my $fh, '-|', $cmd 21 or die open: $!;
print while $fh;
close $fh;
return $? 8;
}
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Re: How to compile just the current perl module, ignoring all the other included modules
On Mon, 23 Jan 2012 12:38:44 -0500, Nemana, Satya wrote: I tried perl -c also with the same results. It takes 4-5 minutes to know that I missed a some where. It is very painful. 4-5 minutes?! Either you have an unbearably slow computer or something is not right. Please post details. It sounds like some module is doing ridiculous computations in its main code instead of being encapsulated in subroutines. It should be tracked down and shot^Wrefactored. That's likely to cause all kinds of problems, so working around it like you're trying isn't really the answer. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Difference between and grep EXPR,
On Fri, 20 Jan 2012 10:08:31 +0600, Andrey P wrote: I don't understand why I need to use a list assignment for say scalar(()=$fh); but not for say scalar(grep /./, $fh); From perlop: If a FILEHANDLE is used in a context that is looking for a list, *a list* comprising all input lines *is returned*, one line per list element. From perlfunc: grep EXPR, LIST Evaluates the BLOCK or EXPR for each element of LIST (locally setting $_ to each element) and *returns the list value*... Because grep is defined to return the number of elements in scalar context. Keep reading perldoc -f grep one more sentence: In scalar context, returns the number of times the expression was true. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: FW: Perl to python converter
On Fri, 23 Dec 2011 17:38:35 +, fudmer rieley southofmex...@yahoo.com wrote: I would love to work on this type of project, but I am a beginning perl programmer. You'll find more assistance outside of a beginning Perl group. If you want to pursue this, your best bet is to pair up with an experienced Perl programmer that you find on somewhere like Perlmonks, and advertise that you have XML/XSLT experience to bring to the party. On this list, your options are more or less limited to asking how you can become a better Perl programmer. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Regex : Extract data between { } spanning in multplie lines
On Fri, 23 Dec 2011 01:56:40 -0800, iand wrote:
Ex file.txt:
A1 {@ a d e \n a b c}
A2 {@ 1 {2 3} \n a b c \n d e f}
I need to extract these separately :
{@ a d e a b c }
{@ 1 {2 3} \n a b c \n d e f}
perl -lne 'print $1 if '~/^[A-Z0-9]+\s\{.*$/m' file.txt I can extract
data by grouping after \{ in regex but how to span over multiple lines
and make this work. Need pointers.
May I suggest http://search.cpan.org/dist/Text-Balanced/ for this type of
endeavor.
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Re: ipc question
On Wed, 14 Dec 2011 20:42:10 -0300, Tessio Fechine wrote: I have a cgi application that has a two way communication with a ldap application via open2: I need to keep communicating with the same ldap.pl process as other cgi scripts are launched: Sounds like you want a named pipe. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: File health check on *nix system using stat
On Sun, 11 Dec 2011 10:40:24 -0400, frank cui wrote: Ok, to make this question more specific, the author of this book is making a program to check if the files can be read off from the disk. And he does so by checking two steps, first is making sure the meta data of this file looks fine, and secondly by reading byte by byte from this file to actually check the file's content readability. As a toy example demonstrating the use of filetest operators and sysread (), this is okay. It's hard to come up with decent short examples. Just as long as you don't come away thinking that this is really how you would test to see if you could read a file. I see people using access checks all the time when they should simply be testing that they can open() the file instead. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: File health check on *nix system using stat
On Sat, 10 Dec 2011 11:11:15 -0400, frank cui wrote:
# attempt to read the directory entry for this file my @stat =
stat($name);
if ( !$stat[4] !$stat[5] !$stat[6] !$stat[7] !$stat[8] ) {
return 0;# according to the code context, here
it is saying the file is NOT ok
What is the program trying to accomplish? What does ok mean for a file
in the context of this exercise? The empirical derivation from the code
doesn't seem useful.
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Re: Make a script to run multiple scripts
On Thu, 01 Dec 2011 12:38:56 -0500, Ryan.Barracuda wrote: I have 7 perl scripts that I want to run simultaneously from the command line with the possibility of growing this number. I'm pretty new to perl, so thought in the mean time it would be a good idea to create a perl script to run multiple scripts. I could just add to this file as needed if more scripts are created. What is the best way to do this? Consider spawning code rather than programs and using Parallel::ForkManager: http://search.cpan.org/~dlux/Parallel-ForkManager-0.7.9/lib/Parallel/ ForkManager.pm -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Simulate `sh -x'
On Jun 24 2002, 4:44 am, davidtg-perl-beginn...@justpickone.org (David T- G) wrote: ...and then Peter Scott said... % % Would you like tracing that goes off when you go into a function? Suppose % % if you gave a numeric argument to 't' it would trace up to that depth % % in subroutine calls beneath the current level but not beneath? That % % might be doable (as a patch to the debugger). % % Hmmm... That's a pretty attractive idea, actually. % % I'll see if I can whack it out. 'Course, it won't show up in an actual % release until 5.8.1, since 5.8.0 is on the verge of release. No, that's not a typo, I really am following up a thread from 2002. I finally got around to implementing this patch. If I'd known how easy it was going to be I'd have done it earlier. Okay, so I'm a bit slow :-) It's in the blead version of perl and will be in subsequent releases. Enjoy. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Perl module for Gmail
On Sun, 20 Nov 2011 12:27:31 -0800, samjesse wrote: I need a Perl script which will connect to my gmail and download the unread emails from a certain folder. But not all the unread emails, only those with a certain subjects and from a certain sender. after that mark them as read and leave them on the server. those emails must be stored appended in a file on the local hard drive. I do this with Net::IMAP::Client. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: passing arguments to perl function with - in the string
On Tue, 29 Nov 2011 18:19:59 -0500, Nemana, Satya wrote: P.S : unfortunately, I cant provide more details due to the IP restrictions, sorry about that, hope you understand, otherwise would have posted the code in the first go. This is a common constraint. You can always post a version of the code that exhibits the same problem but has been cleansed of all IP restrictions. I and many others have had to do exactly this. It has the advantage that in the process you are likely to catch any simple errors and thus solve your problem faster and without the need for external help. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: need help with a form
On Sun, 20 Nov 2011 23:04:28 -0800, Kevin Locke wrote: I need help with getting a form for my church's website to work. Can someone help me with the code to send the information to my email. I would appreciate any input. form id=contact_usquot; class=appnitro method=post action=cgi- bin/contact_us.html Well, your first problem is that the action target of the form is an HTML page instead of a CGI program. What code have you got so far? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-cgi-unsubscr...@perl.org For additional commands, e-mail: beginners-cgi-h...@perl.org http://learn.perl.org/
Re: Fwd: RE: overriding a custom compiled perl binary
On Wed, 16 Nov 2011 02:25:18 -0500, shawn wilson wrote: Yes, it was 5.6.1. I wish I had the perl source code to compile. That would be the simplest solution. The perl binaries where provided by a vendor and the product only works with the customized version of perl they compiled for us. The vendor doesn’t exist any more. You have a bigger problem in that you are living on borrowed time with a 10 year-old version of perl that even if it were not custom, is no longer supported. At any moment something could cause this to stop working. You can't just freeze your whole environment, as evidenced by the fact that you are trying to make a change to @INC already. Tell us more about what you mean by only works with the customized version of perl as in, what not working looks like. Activestate used to distribute perl binaries that had @INC compiled in as long placeholder strings that their installation tool then modified for the local installation. So theoretically you could edit the binary to replace the paths with anything the same length or shorter. As if you weren't out on a long enough limb already. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Taint mode CGI problem
On Fri, 11 Nov 2011 19:08:18 -0300, Tessio Fechine wrote:
#!/usr/bin/perl -T -w
use strict;
use CGI;
$ENV{PATH} = '/var/www/cgi-bin/';
my $exec = 'search.pl';
my $c = CGI-new();
print $c-header(), $c-start_html(-title = It's alive!\n), \n;
my $search = $c-param('search') || 'nobody'; !system $exec, (cn=.
$search . *) or die $exec: $!\n;
print $c-end_html(), \n;
---//---
When I run it from command line (./crap.pl), it works just fine. But
when I try to run it from apache, as a CGI script, I get this error in
error_log:
Insecure dependency in system while running with -T switch at
/var/www/cgi-bin/crap.pl line 14., referer: http://frodo/crap.html;
perldoc perlsec. You haven't untainted $search.
Consider embedding the LDAP search functionality in your CGI, or better
yet, abstracting it to a common module used by both search.pl and your,
er, crap.pl. Code duplication is so enervating.
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Re: bootstrap.pl for setting up my machine
On Sat, 29 Oct 2011 23:24:10 +0200, Sime Ramov wrote: * Shlomi Fish shlo...@shlomifish.org [2011-10-29T19:03+0200]: Since you're not interested in the output of the pkg_add command, you should do: system(pkg_add, $_); Actually, I am. I want to be able to interface with the program. E.g. if there are multiple flavors for some package, `pkg_add` might prompt me which one to install. system() will still let *you* interface with pkg_add. Do you want your program to be able to interface with pkg_add instead? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Help with Getopt::Std
On Sat, 22 Oct 2011 11:58:38 +1300, newbie01 perl wrote: Am just trying to port 1:1. Quite painful trying to figure out how to get awk-like behavior in Perl especially when trying to do some calculation on some specific fields. Awk is Perl's closest ancestor on the evolutionary tree, from one point of view anyway. There's even a program a2p that comes with perl (http:// perldoc.perl.org/a2p.html) for making transitioning automatic, if not easier. Post what you're having trouble with here and we can help. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How to put an AND in a regex?
On Thu, 13 Oct 2011 10:33:17 +, Hamann, T.D. (Thomas) wrote:
I am trying to write a regex that should only match when certain
patterns are not present, e.g. when a line does not start with either a
digit or ALL-CAPS text. I figured I could use negative look-aheads for
this.
I can write it as:
if (/^(?![[:upper:]][[:upper:]])/) {
if (/^(?!\d)/) {
s/^/test/;
}
else {
}
}
else {
}
However, I was wondering whether there was a way of writing this as a
single if loop, because there are much more than two situations that
should not be matched.
I tried to write it as:
if (/^(?![[:upper:]][[:upper:]])|^(?!\d)/) { s/^/test/;
}
else {
}
but this means if one option is not matched the other one is matched,
which is not what I want. So I need something that does the equivalent
of Don't match this AND don't match this. Is this possible in a if
loop, or should I use something else?
Am I missing something about why this approach won't work for you:
if ( ! /\A[[:upper:]][[:upper:]]/ ! /\A[[:digit:]]/ )
Seems easier to understand.
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Re: Updating Perl without admin
On Wed, 12 Oct 2011 20:18:20 -0500, Chris Stinemetz wrote: To use perlbrew, it is required to install curl or wget first. perlbrew depends on one of this two external commmands to be there in order to fetch files from the internet. My unix OS doesn't have curl or wget. Is there a work around? Install one or both to a directory you can write to and put it in your path. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How to get the multiselect select box or checkbox element values WITHOUT using CGI module
On Sat, 01 Oct 2011 01:00:47 -0700, Rajeev Prasad wrote: I thought it would be overkill (RAM, CPU etc.) to use CGI.pm when all i need is to get values out of form-variables. but i am going to settle for CGI::Simple Do you have any figures on how the trivial use of RAM/CPU by CGI.pm impacts your application noticeably? Because programmer time is, in the absence of proof of anything else, the most precious resource, and so anything that takes longer than typing use CGI; is overkill. Especially if it requires downloading something not in core. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: running perl script from inside another script collecting output in array
On Wed, 14 Sep 2011 21:07:31 -0700, Rajeev Prasad wrote:
thecalledscript.pl needs a filename as argument.
here is how i am calling it from a thecalling_script:
{
local @ARGV;
@ARGV = ($filename);
require thecalledscript.pl;
}
issue is, the called script prints some filenames after completion to
STDOUT. how can i collect them into an array variable?
You would be better off calling it with backticks. Otherwise you have to
try fragile techniques such as tying filehandles.
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Re: how to calculate the uncover region
On Tue, 13 Sep 2011 04:54:40 -0700, Lemon wrote:
I have some segments start and end position on a reference sequence, I
want to calculate the uncoverage region for the reference;
for example: reference sequence length= 100,
name [start,end]
segment 1 [1,20]
segment 2 [2,28]
segment 3 [50,100]
segment 4 [5,38]
so uncover region = [38,49]
now I already have %pos{start}=end structure for those segment position,
could somebody give a good method?
By the usual definition the uncovered region is [39,49]. Here's an
approach:
$ cat differ
#!/usr/local/bin/perl
use strict;
use warnings;
use Set::IntSpan; # http://search.cpan.org/perldoc?Set%3A%3AIntSpan
my ($diff, @sets) = map { Set::IntSpan-new( $_ ) }
qw(1-100 1-20 2-28 50-100 5-38);
$diff -= $_ for @sets;
print $diff\n;
$ ./differ
39-49
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Re: unit test case for this perl code
On Fri, 02 Sep 2011 14:16:30 +0530, anirban adhikary wrote: Hi I have write the following code and Now I have been asked to write a unit test case for this code. But neither I have any idea how to write a unit test case nor I have ever experience with it. So in this case I am asking your help. [Snip program that deletes old records from a database] If someone used the words unit test in a request to you then they likely have an existing testing environment and expectations of how tests should behave and what scope they have. Or is this the first unit test that the person asking you will have? So find out what unit test means to them, because there are many possibilities. Assuming they used the term in its usual sense, this test would be one unit out of many others, so what do those other tests do, what protocols do they follow, where do they send their results? Without knowing those things any well-meaning answers you could get here would probably lead you in the wrong direction. Tell us what you find out. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Accessing IMap accounts messages via Perl.
On Sat, 03 Sep 2011 13:39:47 +0200, werner wrote: Am 03.09.11 13:31, schrieb Sean Murphy: All. How can I access my IMap messages from Google via Perll. I wish to extract the message body only. how about Mail::IMAPClient? Or Net::IMAP::Client... -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/certificates/perl-programming.php -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: regex negative looking up a backtrace
On Wed, 24 Aug 2011 20:24:00 +0530, Ramprasad Prasad wrote:
Assume I have to find the first unique character in a string
$string = abtable;
# t is the first unique string
I tried using a negative backtrace lookup to get the answer in a single
regex ... But something is missing.
/(.).(?!\1)/ print $1;
it seems fine ... But doesn't work
The easier way would be with code instead of a regex:
use strict;
use warnings;
use 5.10.0;
@ARGV or @ARGV = (qw(abtable zzabtable abcabc zbbb abcdefabcdefg q qqq));
OUTER: for ( @ARGV )
{
my @c = split //;
my %n;
$n{$_}++ for @c;
for ( @c )
{
next if $n{$_} 1;
say;
next OUTER;
}
say FAIL: $_;
}
% ./proggie
t
t
FAIL: abcabc
z
g
q
FAIL: qqq
But if you really want a regular expression to do the job:
use strict;
use warnings;
use 5.10.0;
@ARGV or @ARGV = (qw(abtable zzabtable abcabc zbbb abcdefabcdefg q qqq));
for ( @ARGV )
{
say
/\A # Starts with
(.*?) # Minimal string, possibly null, then
(.) # Candidate character
(??{# Evaluate code
index($1,$2) = 0 # If first capture contains candidate
? '(*FAIL)'# Assert match failure
: '(*ACCEPT)' # Else success
}) # Followed by
(?!.*\2.*) # Chars not containing candidate
/x ? $1\[$2\]${^POSTMATCH} : FAIL: $_;
}
%proggie
ab[t]able
zzab[t]able
FAIL: abcabc
[z]bbb
abcdefabcdef[g]
[q]
FAIL: qqq
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Re: How to grab last element of array from split with no temporary variables?
On Thu, 11 Aug 2011 23:30:32 -0700, John W. Krahn wrote:
Peter Scott wrote:
On Thu, 11 Aug 2011 16:17:51 -0700, siegfried wrote:
Is there a way to do it with less typing? How can I do it without
creating a temporary variable @p? Thanks, siegfried
find /xyz -exec perl -e 'foreach(@ARGV){ my @p=split /; rename $_,
./$p[$#p].txt } '
Try this:
find /xyz -type f -print0 | perl -F/ -0lane 'rename $_,$F[-1].txt or
warn $!'
That won't work as that reads the contents of the files and not the file
names.
No, STDIN is the list of filenames; Perl's not taking that as @ARGV.
Observe:
$ ls -lR /tmp/xxx
/tmp/xxx:
total 4
-rw-rw-r-- 1 peter peter0 Aug 14 11:04 a
drwxrwxr-x 2 peter peter 4096 Aug 14 11:04 yyy
/tmp/xxx/yyy:
total 0
-rw-rw-r-- 1 peter peter 0 Aug 14 11:04 b
$ pwd
/tmp/zzz
$ find /tmp/xxx -type f -print0 | perl -F/ -0lane 'rename $_,$F[-1].txt
or warn $!'
$ ls -l
total 0
-rw-rw-r-- 1 peter peter 0 Aug 14 11:04 a.txt
-rw-rw-r-- 1 peter peter 0 Aug 14 11:04 b.txt
$ ls -lR /tmp/xxx
/tmp/xxx:
total 4
drwxrwxr-x 2 peter peter 4096 Aug 14 11:05 yyy
/tmp/xxx/yyy:
total 0
--
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Re: How to grab last element of array from split with no temporary variables?
On Thu, 11 Aug 2011 16:17:51 -0700, siegfried wrote:
This works!
Really? I get find: missing argument to `-exec'
I think your command also renames directories. You want that?
Is there a way to do it with less typing? How can I do it
without creating a temporary variable @p? Thanks,
siegfried
find /xyz -exec perl -e 'foreach(@ARGV){ my @p=split /; rename $_,
./$p[$#p].txt } '
Try this:
find /xyz -type f -print0 | perl -F/ -0lane 'rename $_,$F[-1].txt or
warn $!'
That should give you a good excuse to read perlrun :-)
--
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Re: Choosing between look up tables
On Fri, 08 Jul 2011 09:53:05 -0700, Steven Surgnier wrote: Hi everyone, I could use both suggestions and answers on the follow topic. The problem I'm trying to solve is quite simple: I must parse through a large csv file. A field within the csv will signify which product type the included data is associated with. Once the product type is known then a field within the same csv (a 64 byte long hex string) must be parsed out. The hex string is converted to binary where each binary bit represents pass/fail for a particular functional test. Each functional test is unique and the index of said test in the 512 bit string may differ by product type. Everything described so far I'm comfortable tackling. Now to the real question. My initial direction with this problem was to have a separate functable.pl file with unique arrays for each lookup table (the value of the each array location was simply a scalar of the test name). Then use functable.pl in the main parsing script and reference the desired lookup table. If I knew every lookup table ahead of time, I would of course just include them in the parsing script. However, new product types will always be around the corner. So is this a reasonable solution or a rookie mistake? Or should I simply have a .txt file that might look like the following: ### # begin: product1 testA,0 testB,8 testC,16 testD,32 # end # begin: product2 testA,2 testB,4 testC,8 testD,16 # end ### Then simply read in the .txt file and build the array from within the main parsing script as opposed to referencing an array in a separate file? It seems as though you are talking about data rather than code; hard to say because you don't describe how the functional tests may vary. But if all the variations can be captured in data then store it as data, either in a single file if there's not much of it, multiple files if you want to partition responsibility for updating new product types, or a database if it's really dynamic. Don't create reams of code that initializes arrays to literal lists, it's excruciating to read. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl4/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: discover all packages subclassing some other package
On Sat, 11 Jun 2011 08:25:15 +0200, marcos rebelo wrote:
I need to discover all the packages (not files, the symbolic tables)
that are child of my package, something like:
my @child = map { $_-isa('My::Class') } -ALL_PACKAGES-
How do I create the -ALL_PACKAGES- list?
Class::Inspector-subclasses.
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Re: timestamp with milisecond
On Fri, 03 Jun 2011 19:47:53 -0400, Uri Guttman wrote: regardless of the need for millisecond info, use the POSIX::strftime function as it does all of that formatting timestamps for you. and since you pass it a string you can just interpolate the millisecond part into that string. Like so: $ perl -MPOSIX=strftime -MTime::HiRes=time -le '$t = time; $s=sprintf % 06.3f, $t-int($t/60)*60; print strftime %H:%M:$s %d:%m:%Y, localtime $t' 20:38:44.551 03:06:2011 -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: how to do absolute redirect in perl
On Thu, 02 Jun 2011 02:45:25 -0700, anujbhambhani wrote:
$Request-redirect( url = $Std-url(/gp/errors/404),type =
permanent);
works for me
but
$Request-redirect( url = $Std-url(http://www.google.com;,
{absolute = 1});
does not work someone please help
Please provide a complete script of under 20 lines that we can run, tell
us what output you see from running it, and what output you think you
should see instead.
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Re: Ten Years of Considerate Help
On Tue, 31 May 2011 18:13:20 +0100, Dermot wrote: I'd like to put an idea out to see what the list thinks, what if Casey asked for a moderator to take on the role for one year and then the list hold an electon[1] in 12 months time for another moderator. That's as reasonable an idea as any. I could quibble, but I'd sooner see action taken than endless debate. The actual power of any moderator at this point is limited, I think, to requesting an end to certain threads. You can't remove anyone as far as I know; you could have someone removed from the mailing list but it is possible to post to this group via NNTP; that's how I do it. I don't think the means to prevent someone from coming in that way exists. Ultimately we are simply talking about an agreement to respect the requests of one or more people. So that when they request a thread be closed, there isn't a response of, So who put you in charge... oh yeah. This doesn't have to be difficult. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: [OT] Good Perl ISP's
On Wed, 11 May 2011 11:13:51 +0100, Rob Dixon wrote: I wonder what you urgently need that isn't in 5.8.8? Yes, 5.10/5.12 has a few nice things in it, but nothing life-changing. Some modules won't build with the version of ExtUtils::MakeMaker that comes with 5.8.8. Fairly major modules too, although I'm not sure exactly which ones right now. And cpan ExtUtils::MakeMaker won't help since core comes before site in @INC. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Remove all HTML tags
On Wed, 18 May 2011 09:13:20 -0400, Shawn H Corey wrote: On 11-05-18 09:02 AM, Mike Blezien wrote: Is there a perl module available, or a regex method, that will prase an HTML formatted file then remove ALL the HTML elements so you end up with just the text content of the file? HTML::TreeBuilder loads HTML::Element which has a method as_text(). Use HTML::Element::look_down() to find the body, than use as_text() http://search.cpan.org/~jfearn/HTML-Tree-4.2/lib/HTML/TreeBuilder.pm http://search.cpan.org/~jfearn/HTML-Tree-4.2/lib/HTML/Element.pm That's the answer I would give, I would just add to the OP that what you think the text content of a page ought to be may not match what this returns. Text without formatting runs together and for the majority of pages produces a useless mess. Usually more complex parsing is called for based on specific knowledge of the page. Although if all you want the text content for is further machine processing like checksums, concordance, or indexing, then this is fine. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Rounding Date/Time
On Mon, 02 May 2011 11:46:42 -0500, Matt wrote: Have a date: 2011-05-02-16:40:51 [...] I need to round it to nearest 5 minute point. 2011-05-02-16:40:51 If you care about things like daylight savings time adjustments, calendar changes, or leap seconds, the answer requires considerably more thought (use DateTime and do only one arithmetic operation to adjust the time). People who spend much time learning about time peculiarities tend to think of those considerations constantly. They only matter to you if you don't want to accidentally generate a time that didn't exist in your locale, e.g. 2am on a day that the clocks advanced. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: special method name start with _
On Thu, 28 Apr 2011 13:21:56 +0800, Jeff Pang wrote: I may think Perl OO (not moose) doesn't have private or protected methods as other languages like Java/Ruby. _method can be accessed from anywhere. In your example, yes. But Moose *is* Perl's O-O, it's just a wrapper around it. Perl provides enough flexibility to do all kinds of things. See http://search.cpan.org/perldoc?MooseX::Privacy. (That's Moose-X, not Moo-Sex.) Class::Std can do this too. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Fwd: how to parse complex table
On Sun, 24 Apr 2011 18:14:52 -0400, galeb abu-ali wrote:
I revised the code to the following:
[...]
for my $file( @ARGV ) {
open( my $IN, , $file ) or die Failed to open: $!\n;
my( %cog_cat, %cog_id, @cogs, $oid, $locus, $source, $cluster_info
);
while( my $line = $IN ) {
chomp $line;
if( $line=~ /COG_category/ ) {
( $oid, $locus, $source, $cluster_info ) = split /\t/,
$line;
push @{ $cog_cat{ $locus } }, $cluster_info if(
$cluster_info );
} elsif ( $line=~ /COG\d+/ ) {
( $oid, $locus, $source, $cluster_info ) = split /\t/,
$line; push @{ $cog_id{ $locus } }, $source if( $source );
push @{ $cog_id{ $locus } }, $cluster_info if( $cluster_info
);
}
}
Be ruthless about removing duplication. The more unnecessary code you
can prune, the more what's left reveals its true intention, like
chiseling away everything that is not David from a block of marble :-)
So in the above, you can take the line
( $oid, $locus, $source, $cluster_info ) = split /\t/, $line;
from both clauses and put it before the if statement. Also, Perl's topic
variable allows you to eliminate the use of certain variables that
otherwise serve no purpose, like $line in your code is only there to get
at its contents. So instead you can say
while ($IN) {
chomp;
if ( /COG_CATEGORY/ ) {
my ( $oid, $locus, $source, $cluster_info ) = split /\t/;
See also how I declared those four variables right there? Remove their
declaration from before the while loop now and you've gotten rid of some
more duplication and unnecessarily wide scoping.
Many thanks again! Must've spent ~ 4 days on this. I've been flirting
with Perl less than a year, it's so seductive I find myself debating
whether to go back to school.
Heh, camels can be like that :-)
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Re: Creating web pages using Perl.
On Sat, 23 Apr 2011 18:14:46 +1000, Sean Murphy wrote: I am starting another project and I wish to know the best method of creating a web page via Perl. I don't want to reinvent the wheel here. The perl script must generate plain 4.0 HTML code. I am not after any bells or whistles on the page. The Perl script will go through all my Audio books and group them by author, title and titles in series. I was thinking a table with the below columns: Author, Series, Title, stream, category and rating. Rating is Adult, Junior, etc. Category is SiFi, thriller, etc. If the person clicks on the title, a brief description would pop-up. This would be a text file that it would show. Stream it would send the audio directly to the browser. I find HTML::Template a good solution for the beginner who knows HTML. The Template Toolkit is awesome in its power but takes longer to learn for basic jobs like what you describe. If and when you learn the Template Toolkit for some other reason then you're likely to use it for everything including tasks like this one. The CGI.pm module can generate HTML via functions or methods with the same names as the elements. It was very popular at one time although templating makes a lot more sense. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Ten Years of Considerate Help
On Fri, 22 Apr 2011 13:39:15 -0400, Casey West wrote: Shortly after this mailing list got off the ground I wrote an article trying to instigate the Perl community to embrace the idea of a safe place for newcomers, both to Perl and programming. It's been pointed out I was marginally hyperbolic, but only a little. My abuse of the comma, however, has no justification. I quoted from the preface of a popular Perl book at the time, closing my argument thusly: But, paradoxically, the way in which Perl helps you the most has almost nothing to do with Perl, and everything to do with the people who use Perl. Perl folks are, frankly, some of the most helpful folks on earth. If there's a religious quality to the Perl movement, then this is at the heart of it. Larry wanted the Perl community to function like a little bit of heaven, and he seems to have gotten his wish, so far. Please do your part to keep it that way. -- Preface, Programming Perl 2nd Edition http://www.perl.com/pub/2001/05/29/tides.html Thanks, Casey, for coming back and demonstrating that intelligence and politeness are not mutually exclusive. I encourage people who haven't read your article linked above to do so; it contains some excellent and concise explanations of the rationale for civil treatment of beginners. One more explanation that might help was given to me by the founder of the O'Reilly School of Technology, who I am creating courses for. He is very enthusiastic and inspiring about education, and wants to make sure all the OST courses follow his vision, and he recognizes that expertise is not the same thing as teaching ability, so he impressed upon his authors the following model. He breaks down students into a bell curve. On the right tail are the early adopters like Randal, me, Uri, Casey, and other experts we could all name. These people will learn something, anything, and everything without any external prodding; they just go off and hunt down the resources, read the manual, experiment. They're completely self-starting. The middle of the bell curve - where the most students are - contains people who learn better with varying levels of help and encouragement, ranging from a point in the right direction to more directed help from a mentor. OST courses (and Stonehenge, etc, courses) are for them. They'd be a waste of time for the people on the right tail. People out on the right tail are particularly prone to thinking that the best or only way to learn is the same way they did - self-motivated figuring things out from the manual and experimentation - and that any other approach is inferior or wrong. But it's simply not going to work for the folk in the middle of the curve, who learn a different way. Some folk on the right tail think that if they beat up the people in the middle enough, they'll migrate to the right tail - where the right people are. Any instances of this actually working are so rare as to be the exceptions that prove the rule. Note that this is a bell curve of learning types, *not* intelligence or ability. And as other posters have pointed out, someone can be in the right tail in one discipline, like bioinformatics, and in the middle in another - like Perl. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Nature of this list
I remember when Casey West and Kevin Meltzer started this list. Casey was very specific on-line and in person about it being a place where newcomers could ask questions without being flamed. The FAQ bears this out: : 2.1 - What is the list for? : : A list for beginning Perl programmers to ask questions in a friendly : atmosphere. That is also the complete description of this group at http:// lists.perl.org/list/beginners.html. The FAQ goes on: : 2.3 - Are there any rules? : : Yes. As with most communities, there are rules. Not many, and ones that : shouldn't need to be mentioned, but they are. : : * Be nice : * No flaming : * Have fun :[...] : * If you think what you are writing may be taken in a way you didn't : intend, please add a smiley :-) Many flame wars are stopped by a simple : smiley! : * No flames. If your fingers are burning as you are typing the email, it : would likely be best not to send it. If anything is clear from that FAQ it is that the intention is to avoid flames on this list. Casey and Kevin appear to have stopped monitoring this group some time ago, though. There is no shortage of lists, groups, or forums where people can get flamed for not following the rules, and people who want to flame them have an outlet for doing so. I've already stopped reading most of them because it's not worth my time when most of the content is arguments about conduct. I don't know whether communities inevitably fall into that mode after a while but this one at least had a good run and I'll be sorry if I end up leaving it too. Andy Lester had a good article about this: http://perlbuzz.com/2010/11/ think-for-perls-sake.html. But judging from the responses it seems he and I may be in a minority. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: sample distribution
On Tue, 19 Apr 2011 16:29:16 -0700, ai nguyen wrote: A population of 20 cows, each one has age and weight (known). Device this population into 2 group, each group has 10 cows. Questions: How to pick a cow on each group so that a distribution of AGE and WEIGHT on each group is similar. Show your strategy or/and implement it in PERL. Is this a question on a quiz or test you're taking? Do the people giving the test have the expectation that your answer is a measure of your abilities or those of people you've asked for help? How far have you gotten with a solution? Or if you're just posing a question as a challenge for people to exercise their brains, this would be better off in the Perl Quiz-of-the-Week list (which hasn't seen any traffic in aeons). -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Alternative to goto
On Fri, 15 Apr 2011 08:48:10 -0400, shawn wilson wrote:
but, sense it is jumping to a different place in the stack, isn't it
more efficient than doing the above mentioned
my $done = 0;
while( !$done ){
$done = 1 if( contition );
do_work;
}
vs
for(;;) {
goto DONE if( contition );
do_work;
}
label DONE;
i'd think the later would be faster not only because you are jumping to
a memory location and because you're not assessing a value every time.
Exactly why would you care about what would be at best milliseconds of
execution speed more than maintainability? Seems like you'd be better
off programming in assembler if that's your priority. Execution speed
hasn't been a primary concern since the '70s, if it was even one then.
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Re: format output from system command
On Fri, 15 Apr 2011 08:53:12 -0700, sono-io wrote:
On Apr 15, 2011, at 8:37 AM, Alan Haggai Alavi wrote:
open ('FILEOUT', '', 'cmdout') ||die cant open cmdout: $! \n;
Is that O.K.?
You are still using a bareword filehandle.
Putting single quotes around the filehandle allows it to pass Perl
Critic, so I was just curious about the difference.
If you're concerned about following the recommendations of Perl Best
Practices (which PerlCritic is based on), I'd hope you'd follow the one
that says to not create bareword filehandles.
I adopted the PBP recommendation to always wrap the lexical filehandle in
curlies when using it as the indirect object, and I like the result a lot.
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Re: Calling subroutines with the sigil
On Wed, 13 Apr 2011 16:07:47 -0700, sono-io wrote: Hello, I read somewhere that it's bad practice anymore to call a subroutine like this: subroutine(); I've also read where it's faster to call a sub like this: subroutine; than it is to call like this: subroutine(); Is this true? I searched but I can't find a good recent discussion of this. What is the best (preferred) way to call subroutines today? It is better to call them as subroutine() provided that you don't define a subroutine with the same name as a Perl builtin. It's better to learn the names of the Perl builtins than to give up and always use subroutine. The builtins are all listed in perlfunc. It's actually not that hard to get them. The only one that people habitually collide with is log(). If you're worried about the speed overhead of one vs the other then either you are worried about the wrong thing or you have bigger problems. Worry about speed only when (a) you've determined that your code is too slow, and then (b) you've profiled it to find out where the bottleneck is (hint: it's not likely to be in subroutine call overhead). -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Alternative to goto
On Thu, 14 Apr 2011 14:05:54 +0300, Shlomi Fish wrote: Hi Uri and Peter, Regarding the Goto statement considered harmful myth, see what I wrote about it here: Myth is generally used to descibe something widely thought to be true that is in fact false. The assertion that goto is harmful has hardly been proven false. The entire GOTO statement considered harmful is quite a myth. Granted, Dijkstra wrote an article with this title, and many people agreed with him. But, on the other hand, some people have demonstrated that it is possible to do structured programming with goto statements, and sometimes even better with them than without them. Of course you *can* replace control structures with GOTOs, they all compile to machine code that uses either GOTO or program counter stacks anyway. The reason we even have GOTO in languages is because the first ones were assembler code that reflected the machine code. Ancient history. For example, Don Knuth wrote an article Structured Programming Using Goto Statements (rumouredly sub-titled 'Goto Statement Considered Harmful' Considered Harmful) in which he deomnstrated exactly that. And I take this view as well. Knuth's article is at http://citeseerx.ist.psu.edu/viewdoc/download? doi=10.1.1.103.6084rep=rep1type=pdf . He doesn't call Dijkstra's statement harmful. He spends half the paper discussing how to remove GOTOs and then brings up some cases where using them would make certain code run faster, which in 1974 was often more important than programmer time but almost always isn't now. Knuth also had spent time developing languages like MIX that needed GOTO; MIX was a hypothetical machine code (sort of an early Parrot). It included card punch devices and drum units. So he was used to writing programs that had to use GOTO. Only assembly programmers these days still need it. Like I said: I've never seen code that was clearer with a GOTO than without it. Shorter, maybe; faster, maybe, but not clearer. Even if I ever did, it would be the exception that proved an unusually universal rule. Any possible justification for a GOTO would be so arcane that it is counterproductive to suggest it at all in a beginner's group. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Calling subroutines with the sigil
On Thu, 14 Apr 2011 08:49:45 -0700, sono-io wrote: The only one I was concerned with was a sub called if, Sounds like a great device for an obfuscated Perl contest entry. That's the only place I want to see it, though. but it doesn't look like it's a built-in function. However, just so it makes more sense to me and to be on the safe side, I've renamed it if_routine. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Alternative to goto
On Thu, 14 Apr 2011 20:44:57 +0100, Rob Dixon wrote: [ Good arguments about goto ] A final note, perldoc perlsyn says A loop's LABEL is not actually a valid target for a goto; it's just the name of the loop. and I am left wondering what this means, as I have had no problem writing a 'goto' targetting such labels. I wonder if this is a mistake in the documentation, or it is simply saying that such a goto is deprecated? Mistake by the look of it. To the discoverer go the rights of perlbug :) -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Alternative to goto
On Thu, 14 Apr 2011 10:47:17 -0700, sono-io wrote: On Apr 14, 2011, at 10:15 AM, Uri Guttman wrote: goto just shouldn't be in your vocabulary. there is no reason for it at all in any decent language, especially perl. I've been following this thread and I'm just curious. If goto is so bad, why did they add it to Perl? Perl's goto is pretty old. Larry was feeling permissive and in a frame of mind to make BASIC programmers happy. He regrets it. The perldoc for goto says he has never found a reason to use it. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Alternative to goto
On Wed, 13 Apr 2011 21:57:53 -0700, Mariano Loza Coll wrote: Hi all, OC I never bothered to learn how OC to use goto because it's deprecated (or on it's way?), but it OC seems like this would be a good place to use it. At the same OC time, I understand that use of goto is akin to sleeping with your OC sister among most programmers in the Perl programming community. Like Owen, I've come across many a recommendation AGAINST using goto in Perl. And (like Owen?), I have yet to find one that explains clearly the reasons arguing against its use. If nothing else, it has made me very curious... Can any of the more experienced programmers (ie. nearly everyone else on this list by my standards) point to a good explanation as to why one should avoid goto in Perl (or coding in general)? I looked around in perl-begin.org but couldn't find anything obvious. Once again, I make my request from the purest desire of learning Perl the best way I can. Here is the definitive explanation: http://www.cs.utexas.edu/users/EWD/ ewd02xx/EWD215.PDF . I have never, ever, seen a situation where the use of goto would have resulted in clearer code. Considering it has always indicated to me that the person considering it has not understood the problem properly or modeled its solution well. Goto simply is not part of the vocabulary of clear coding. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: perl dd
On Fri, 01 Apr 2011 10:51:58 +0300, Shlomi Fish wrote: 2. The problem with 1E9 is that I think it's a floating point number (though Perl 5 may have some intelligence there). Not sure it matterns a lot for Perl but if you do something like 1.27E9 you may get weird side-effects due to: Yup, anything in scientific notation becomes floating point, but I doubt it's going to matter in the case of 1E9: $ perl -MDevel::Peek -e 'Dump($_) for 1E9, 10, 1E2' SV = NV(0x8a4aee8) at 0x8a367b8 REFCNT = 2 FLAGS = (NOK,READONLY,pNOK) NV = 10 SV = IV(0x8a367c4) at 0x8a367c8 REFCNT = 2 FLAGS = (IOK,READONLY,pIOK) IV = 10 SV = NV(0x8a4aef0) at 0x8a367d8 REFCNT = 2 FLAGS = (NOK,READONLY,pNOK) NV = 100 -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: perl dd
On Thu, 31 Mar 2011 12:07:41 +0200, Shlomi Fish wrote: Also, Larry Wall has allowed Perl 5 numeric constants to contain underscore so you can write 10**9 as 1_000_000_000 instead of 10 which is much less readable and also more error-prone. (Larry Wall)++ . 1E9 seems to capture your intention even better :-) -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: PERL CGI SCRIPT killed by apache on client abort
On Sat, 26 Mar 2011 15:56:08 +0100, Przemysław Rejf wrote: My upload script which uses upload hook works really nice. After the upload ends it writes some debug stuff to log file and sends some info to other host. When client aborts the upload the reminder of the script after hook is not executed and i get an error in my apache log: [Sat Mar 26 14:53:09 2011] [error] [client xxx.xxx.xxx.xxx] (70014)End + of file found: Error reading request entity data, referer: http://lo +calhost/upload [download] I'm thinking its the fault of apache, because without abort the script works just fine. Does anyone have any clue about it ? The script: Your script is invoked to read a file from the client. If the client doesn't send it what else would you expect to happen? How can it read a data stream that's not there? It's not apache's fault, it's the client's fault for not finishing what it said it would do or your script's fault for not trapping an exception it needs to handle. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-cgi-unsubscr...@perl.org For additional commands, e-mail: beginners-cgi-h...@perl.org http://learn.perl.org/
Re: shift oo
On Tue, 22 Mar 2011 13:41:59 -0700, Randal L. Schwartz wrote:
Peter == Peter Scott pe...@psdt.com writes:
my $s = Streamer-new;
my $app = sub {
return sub {
$s-open_fh;
my $writer = shift-(
[ 200, [ Content-type = text/plain ], $s ] );
};
};
Peter As it stands, this doesn't make sense because nothing happens to
$writer; Peter so why create it?
I presume you're objecting to the explicit $writer. Certainly, the
value of $writer is also the return value of the inner subroutine, so
that *is* something that could be noted:
Right, the superfluous naming of $writer leads to a lot of head-
scratching. Best guess (if this is an accurate post of the code), that
there was originally some debugging/logging code in there before a
return $writer that got taken out. Although I supposed that the paste
was incomplete. Either way, a giant red herring.
--
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Re: shift oo
On Fri, 18 Mar 2011 17:34:00 -0400, shawn wilson wrote:
here's the whole function (i didn't think i needed to post it because i
get the rest of this code):
Your problem is less to do with Perl than it is with explaining what you
need clearly. Clear thinking and clear communication lead to clear code
so this is an important thing to work on. This thread resembled a bad
rewrite of the Abbott Costello Who's on First? skit.
my $s = Streamer-new;
my $app = sub {
return sub {
$s-open_fh;
my $writer = shift-(
[ 200, [ Content-type = text/plain ], $s ]
);
};
};
That is a fancy piece of code somewhat beyond the usual definition of
beginner. Context is important; you haven't provided all of the
context we need to understand this so there is going to be some guesswork
in the explanation.
This code creates a Streamer object in $s. Then it populates $app with
a reference to a subroutine that when called, will return a reference to
a subroutine that first calls the open_fh() method of $s, then creates in
$writer the result of calling the first argument (to the inner
subroutine) as a code reference, passing it a reference to an array
containing 200, another array ref, and the $s object.
As it stands, this doesn't make sense because nothing happens to $writer;
so why create it? The code certainly does something but either there is
code that you haven't shown us or the writer of this code wasn't thinking
clearly in putting $writer in there.
There are two code refs created and another one passed in these few
lines; it is very compact. Use of this code would go something like this:
$other_ref = sub {
my $ar = shift;
my ($status, $header_ref, $streamer) = @$ar;
my @headers = @$header_ref;
# Do something with those variables...
};
$coderef = $app-();
$coderef-( $other_ref );
$other_ref must be a reference to a subroutine for this code to work. It
is not therefore an object (technically, it could be - it could be
blessed - but that is beside the point, nothing in this code expects it
to be an object).
You need to be very conversant with code references and functional
programming to be comfortable with this code.
--
Peter Scott
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Re: sub routine
On Thu, 17 Mar 2011 19:25:02 -0600, Chris Stinemetz wrote: Take the value of $data[261] and return the solution of: $data[261]+13)/6.6/8/2*10)/10 Your expression there is missing left parentheses. If we guess at where to put them we end up with (($data[261]+13)/6.6/8/2*10)/10 which doesn't make sense because why multiply by 10 only to divide by 10? The code you posted is an odd mix of sophistication levels. Did you write it all, and if not, do you understand it? You seem to be in need more of a beginner's lesson to Perl if you need to know how to construct expressions like that and yet are working with code containing Schwartzian transforms. In general, posting a lengthy program and asking how to enhance it to meet some new requirement is not what this list/group is about; that falls under doing your homework. We're here to teach you how to solve problems, not solve them for you. You might still get solutions - like you did here - but things will go better when you ask for learning instead. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: MRF-ERROR: Is a directory
On Thu, 17 Mar 2011 02:26:06 +0700, indrag wrote: this is the code: #!/usr/bin/perl use NetCDF; The error is coming out of NetCDF.pm. Check all of the calls you make to functions from that module against its documentation. Did you write the program you posted or did someone else? Do you understand it? -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How does the function loading works in Perl
On Wed, 02 Mar 2011 17:02:30 -0500, Shawn H Corey wrote: On 11-03-02 04:15 PM, Parag Kalra wrote: A Perl script may have many functions. When we execute the script via Perl Interpreter, does all the functions are loaded into memory? All the functions are compiled and loaded. Sometimes we just like to keep the coded functions in the script with the idea that we may need them in future. Will removing an un-called functions improve the execution time? Yes but on modern machines, you will need an awful lot of subs to get a noticeable slow down. Right. The AUTOLOAD feature can be used to delay the compilation and loading of a sub I think you mean AutoLoader. Or SelfLoader. They may use AUTOLOAD under the hood but that's not the direction to point the user in. but I have never seen it used in practice. There are a fair number of modules on CPAN using it. And in the core: POSIX, for instance. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: x,y axis graph
On Tue, 15 Feb 2011 19:35:03 -0700, Chris Stinemetz wrote: I am interested in creating a cgi perl script that I can publish on the web that will tie into a mysql database and create a x,y axis graph based on data selection. Any suggestions are greatly appreciated. Suggestion: http://search.cpan.org/~dmaki/Google-Chart-0.05014/lib/Google/Chart.pm -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: x,y axis graph
On Tue, Feb 15, 2011 at 9:35 PM, Chris Stinemetz cstinem...@cricketcommunications.com wrote: I am interested in creating a cgi perl script that I can publish on the web that will tie into a mysql database and create a x,y axis graph based on data selection. Any suggestions are greatly appreciated. Thank you, Chris Stinemetz I use GD::Graph with cgi to create graphs on the fly. There are some examples on http://gdgraph.com/ Regards, Scott
Re: understanding the ||= operator
On Sat, 12 Feb 2011 12:13:13 +0100, Dr.Ruud wrote:
On 2011-02-11 11:26, Alan Haggai Alavi wrote:
$variable_1 ||= $variable_2 is equivalent to $variable_1 = $variable_1
|| $variable_2.
Hmm, I don't buy that, I would say that $x ||= $y is equivalent to
$x = $y unless $x;
alternatively:
$x or $x = $y;
because the setting of $x only needs to happen if $x is false.
Realize that C$variable_1 = $variable_1; can only be optimized away if
no magic is involved.
No, the optimization seems to happen either way:
$ perl -E 'tie $x, F; tie $y, F; say Orcish:; $x ||= $y; say
Unwrapped:; $x = $x || $y; say Done; sub F::TIESCALAR{ bless [],
F }; sub F::AUTOLOAD{ say $F::AUTOLOAD } '
Orcish:
F::FETCH
Unwrapped:
F::FETCH
Done
F::DESTROY
F::DESTROY
--
Peter Scott
http://www.perlmedic.com/ http://www.perldebugged.com/
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Re: Dereference Links
On Fri, 21 Jan 2011 08:01:03 -0600, Mike Flannigan wrote:
I'm trying to dereference the @{$links} produced by WWW::SimpleRobot and
am having a heck of a time getting it done. Can anybody help? You can
see some of the things I have tried below.
That module hasn't been updated since 2001. You'll have a much easier
time using WWW::Mechanize and many more people will be in a position to
help you.
--
Peter Scott
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Re: advangtes of Perl on various languages
On Thu, 06 Jan 2011 09:32:31 +0530, Sunita Rani Pradhan wrote: This is a good question .I am asking for my own career growth . I work as a automation engineer . I used to be in manual testing and moved to automation just been 1.5yr. What does an automation engineer do, and what industry are you in or want to be in? Are you programming embedded devices or microcontrollers? In the video game business or financial services? Are you doing industrial process monitoring, educational software, mobile phone applications, CAD/ CAM, or engineering documentation library interfaces? All of those possibilities and more would have radically different answers and you have not provided any information to differentiate between them. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Function to print Object properties
On Thu, 06 Jan 2011 21:31:11 -0500, Shawn H Corey wrote:
On 11-01-06 09:25 PM, Parag Kalra wrote:
For example if I have a package say Foo::Bar. Now assume that there is
a object called $fob and pretend that I don't know that its an instance
of Foo::Bar
print ref( $fob ), \n;
See `perldoc -f ref`.
The officially blessed :-) way to do this is with Scalar::Util:
use Scalar::Util qw(blessed);
say blessed( $fob );
since this can discriminate between a reference and a blessed reference.
Consider the cases of
$fob = {};
$fob = bless {}, HASH;
for instance.
--
Peter Scott
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Re: perl training material and excercises for freshers
On Mon, 03 Jan 2011 13:26:49 +0530, Sunita Rani Pradhan wrote: I am planning to give Perl training to my juniors in my team. They are new to Perl. Could anyone please send me any Perl training materials with exercises, or links, which I can refer to? Please send me good suggestions also for training. Web-based training with instructor feedback at the O'Reilly School of Technology: http://www.oreillyschool.com/courses/perl1/ -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: 1st line of perl script
On Tue, 04 Jan 2011 01:09:56 -0500, George Worroll wrote: On Windows, that line is just a comment. Neither the operating system nor the interpreter does anything with it. Not quite. Any options on the line (e.g., -T) will be activated. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: advangtes of Perl on various languages
On Tue, 04 Jan 2011 12:42:28 +0530, Sunita Rani Pradhan wrote: I would like to know answers of following questions : - What all advantages Perl has on top of other scripting languages like Python , shell , Java ? - What is the career growth, road map in Perl programming ? These questions are more of a Rohrshach test for the reader than anything else. Without any idea of what goal you are trying to satisfy any answer is essentially useless. It is like the old saw that a recession is when the other guy is out of work and a depression is when you are out of work: aggregate statistics--and industry trends--are of very little importance compared to your personal priorities. If you want a language with a large install base, learn COBOL. If you want cool IDEs, learn Java. Me, I don't care whether there's more money in Java, it wouldn't be enough for me. And if money's the top priority, become a lawyer. So I can't see any answers to those questions being of use unless you tell us why you want to know. Are they an assignment for a term paper? Are you writing a trade magazine article? Or something else? If you're asking in regard to your own career path then we'd need to know a lot more about what your priorities and background are. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Strategy for diagnosing context-sensitive bug
On Tue, 07 Dec 2010 01:24:57 -0800, Jonathan Pool wrote: Are you familiar with the perl debugger? Thanks much for your reply. I haven't used the debugger, partly because its documentation describes it as an interactive tool and it's not clear to me how that works in my context. The script is executed by httpd in response to a browser form submission, which includes a file upload. Every CGI program should be testable from the command line (and CGI.pm can read arguments from there). But if that doesn't work, there is a way to remotely invoke the debugger in this situation. Rather than retype it, I googled and found it in a Perl Journal article saved at http:// www.foo.be/docs/tpj/issues/vol4_3/tpj0403-0008.html . -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Strategy for diagnosing context-sensitive bug
On Tue, 07 Dec 2010 10:33:08 -0800, Jonathan Pool wrote: Every CGI program should be testable from the command line. But if that doesn't work, there is a way to remotely invoke the debugger in this situation. http:// www.foo.be/docs/tpj/issues/vol4_3/tpj0403-0008.html . Thanks. The applicability of this approach is unclear to me. The document says The ptkdb window will appear. But this script is being run by httpd to generate a reply to a request from a web browser's form submission. I don't understand where a window could appear. On whatever workstation you designate through the DISPLAY environment variable. You have to have a basic understanding of X Windows and its client/server model to make this work. As for the command line, yes, but I would be simulating a multipart/form-data http form submission with a file-upload part and hoping that Perl is seeing the same thing. True, it won't be easy, but if you can come up with a test for whatever bug you are experiencing, it will be invaluable for saving time later. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Monitoring ssh connectivity to a server using perl !
On Tue, 23 Nov 2010 21:59:19 +0530, Amit Saxena wrote: Hi all, What's the best way to monitor ssh connectivity, and not just ssh port availability, to a server using perl assuming following constraints ? I tried for Net::SSH but public private key is not allowed. I tried for Net::SSH::Perl etc but these are not built in perl distribution (active perl on windows or part of perl distribution of linux / solaris). Can we do it via IO::Socket::INET ? If it's enough to check that something's listening to port 22: perl -MNet::Ping -le '$p=Net::Ping-new; $p-port_number(22); $p-ping (localhost) or warn SSH down' -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl3/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Email Filter Script
On Fri, 22 Oct 2010 03:35:19 -0400, Mark wrote: I have a college e-mail account. The college uses Outlook webmail. I hate Outlook webmail. You are among friends :) I have multiple e-mail accounts and use one IMAP e-mail client (Tbird) to manage them all; can't be chasing down individual webmail accounts. However, the college Outlook account in question is not accessible via IMAP. So I set up the Outlook account to automatically forward all messages to one of my personal accounts. The college's Outlook server does forward all messages, but in the process it severely alters the messages in the following ways: Can you create a redirection rule instead? http://office.microsoft.com/en-us/outlook-help/automatically-forward- messages-to-another-e-mail-account-HA001150201.aspx -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: PERL MYSQL query IF EXISTS then UPDATE else INSERT
On Wed, 20 Oct 2010 12:07:03 +0530, S Pratap Singh wrote: I want to update my database if the key value is already there then it will update the required field else it will insert the new row in the same table. Insert query works fine but I am not able to figure out how to achieve this IF EXISTS then UPDATE else INSERT using a one liner MYSQL statement . If someone can give me an example to write such query and execute it from perl then it would be really appreciated. This isn't a Perl question, you're asking in the wrong place. This is analogous to asking your auto mechanic what the feeding habits of emus are because you used your car to drive to the zoo. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: perl for systemadministration
On Wed, 20 Oct 2010 17:09:17 +0530, Jyoti wrote: I need your help. Please tell me a good book for perl for system administration. Perl for System Administration -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How can I open a remote ssh session with perl
On Sat, 28 Aug 2010 11:55:01 +0530, S Pratap Singh wrote: Is there any way I can get these interactive output via my script or I am missing something? .. Thanks for your continued help. I need to get those interactive outputs to my script or is there any way to open a psuedo terminal. I do not want to execute command on server it should be examined via my script and then it should get executed . Let me know if this is possible using perl or I have to use any other scripting language like python. Yes, the documentation for Net::SSH::Perl explains how. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How can I open a remote ssh session with perl
On Fri, 27 Aug 2010 09:17:22 +0530, S Pratap Singh wrote: Hello Peter , Did you try executing command top -cd2, iostat 1, vmstat 1 10 etc ? Did you get the output of those command ? vmstat 1 10 works for me; pstree works; but of course you're not going to run top -cd2 this way, that's an interactive program that won't terminate without user input. Neither will iostat 1 terminate; but iostat 1 10 works fine, just got to wait 10 seconds. I don't see anything in your pstree output that looks truncated. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: How can I open a remote ssh session with perl
On Thu, 26 Aug 2010 11:22:29 +0530, S Pratap Singh wrote:
Here is my code which logs in and performs some task but it does not
show the output of top and pstree command what would i do to get the
output of these commands along with vmstat and iostat
#!/usr/bin/perl -w
use Net::SSH::Perl
$host = '192.168.3.36';
$username = 'root';
$login_passwd = 'password';
#$session - close;
#my $cmd = ls -l;
my $ssh = Net::SSH::Perl-new($host); $ssh-login($username,
$login_passwd); #my $arg= join '',@ARGV;
#while ($arg) {
while() {
$cmd = $_;
my($stdout,$sterr, $stderr) = $ssh-cmd($cmd); print
\n$stdout\n$stderr ;
print quiting from the server if eof; }
I just tried this code with a server and credentials of my own and it
worked fine with several commands including pstree. So you have some
problem specific to your configuration that needs debugging. Either the
module isn't built right, you have the wrong credentials, you aren't
connecting, or the remote end doesn't have the right environment,
something like that.
--
Peter Scott
http://www.perlmedic.com/ http://www.perldebugged.com/
http://www.informit.com/store/product.aspx?isbn=0137001274
http://www.oreillyschool.com/courses/perl1/
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Re: How can I open a remote ssh session with perl
On Tue, 24 Aug 2010 14:25:01 +0530, S Pratap Singh wrote: I know how to run command on remote shell using script , but I want to open remote shell using perl and want to run the command manually and terminate the session when I am done as we normally do with shell . CPAN: Net::SSH::Perl . -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Perl obfuscator
On Sun, 22 Aug 2010 03:40:33 -0400, Chas. Owens wrote: But the names (variables, subroutines) can be rendered meaningless. Since picking good names is one of the most important contributions a good programmer can make, trying to understand and change a large body of code that has the worst names possible may not be impossible, but still is excruciating. snip If you do that in Perl 5, you run the risk of breaking the code. Anything that used a symbolic reference would break. [snip] This is why all Perl 5 obfuscators, that I know of, work by encoding the text somehow, not by modifying what perl sees. http://www.stunnix.com/prod/po/overview.shtml : Now, I haven't used it. But it does claim to be an exception to your rule. The users manual has a section on what to do about symbolic name construction. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
Re: Perl obfuscator
On Fri, 20 Aug 2010 14:27:29 -0400, Chas. Owens wrote: There are no good obfuscators. A user can always get the source back out. But the names (variables, subroutines) can be rendered meaningless. Since picking good names is one of the most important contributions a good programmer can make, trying to understand and change a large body of code that has the worst names possible may not be impossible, but still is excruciating. -- Peter Scott http://www.perlmedic.com/ http://www.perldebugged.com/ http://www.informit.com/store/product.aspx?isbn=0137001274 http://www.oreillyschool.com/courses/perl1/ -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
