Aside from trying perldoc <module name> individually for any CPAN module that takes my fancy or going through the file system and looking at the directories I have no idea what modules we have installed. What's the easiest way to just get a big list of every CPAN module installed? From the command line or otherwise. ...
Many beginning programmers write code like this: sub copy_file ($$) { my $from = shift; my $to = shift; `cp $from $to`; } Is this bad, and why? Should backticks ever be used? If so, how? ...
At work I'm using Perl 5.8.0 on Windows. When I first put Perl on, I went to CPAN, downloaded all the sources, made a few changes (in the .MAK file? to support threads, or things like that), and did nmake / nmake test / nmake install. Then, bit by bit, I've downloaded individual modules from CPAN and done the nmake dance. So, I'd like ...
I understand that Parrot is a virtual machine, but I feel like I'm not completely grasping the idea behind it. As I understand, it's a virtual machine that's being made to handle multiple languages. Is this correct? What are the advantages of using a virtual machine instead of just an interpreter? What specifically is Parrot doin...
I have a string with possible command line arguments (using an Read-Eval-Print-Loop program) and I want it to be parsed similar to the command line arguments when passed to Getopt::Long. To elaborate: I have a string $str = '--infile /tmp/infile_location --outfile /tmp/outfile' I want it to be parsed by GetOptions so that it is easi...
I have a string of arbitrary length, and starting at position p0, I need to find the first occurrence of one of three 3-letter patterns. Assume the string contain only letters. I need to find the count of triplets starting at position p0 and jumping forward in triplets until the first occurrence of either 'aaa' or 'bbb' or 'ccc'. Is th...
I switched from Perl to Python about a year ago and haven't looked back. There is only one idiom that I've ever found I can do more easily in Perl than in Python: if ($var =~ /foo(.+)/) { # do something with $1 } elsif ($var =~ /bar(.+)/) { # do something with $1 } elsif ($var =~ /baz(.+)/) { # do something with $1 } The corres...
I'd be very grateful if you could compare the winning O’Rourke's Perl solution to Lundh's Python solution, as I don't know Perl good enough to understand what's going on there. More specifically I'd like to know what gave Perl version 3x advantage: algorithmic superiority, quality of C extensions, other factors? Wide Finder: Results ...
I need to do some simple timezone calculation in mod_perl. DateTime isn't an option. What I need to do is easily accomplished by setting $ENV{TZ} and using localtime and POSIX::mktime, but under a threaded MPM, I'd need to make sure only one thread at a time was mucking with the environment. (I'm not concerned about other uses of loca...
Coming from a Perl 5 background, what are the advantages of moving to Perl 6 or Python? Edit: If you downvoted this because you think it's just flamebait, read the answers below. They're not raving arguments; they're well-written discussions of the pros and cons of each language. Give the Stack Overflow community some credit. ...
Perl 6 has been under development for over 8 years now, and (as ever) there seems to be no end in sight. However, it has had a reasonable implementation for some time, Pugs, and even has multiple implementations now. When I last took a look at Perl 6 a few years ago, it seemed to me that there were lots of interesting ideas, but that e...
I need to pass a regex substitution as a variable: sub proc { my $pattern = shift; my $txt = "foo baz"; $txt =~ $pattern; } my $pattern = 's/foo/bar/'; proc($pattern); This, of course, doesn't work. I tried eval'ing the substitution: eval("$txt =~ $pattern;"); but that didn't work either. What horribly obvious thing a...
In reading about Perl 6, I see a feature being trumpeted about, where you no longer have to do: return "0 but true"; ...but can instead do: return 0 but True; If that's the case, how does truth work in Perl 6? In Perl 5, it was pretty simple: 0, "", and undef are false, everything else is true. What are the rules in Perl 6 when it...
Hi, I have an email subject of the form: =?utf-8?B?T3.....?= The body of the email is utf-8 base64 encoded - and has decoded fine. I am current using Perl's Email::MIME module to decode the email. What is the meaning of the =?utf-8 delimiter and how do I extract information from this string? ...
I'm trying to install Maatkit following the maatkit instructions. I can't get past having to install DBD::mysql. "Warning: prerequisite DBD::mysql 1 not found." When I try to install DBD::mysql from cpan, I get very helpful "make had returned bad status, install seems impossible". Perl is "v5.8.8 built for darwin-thread-multi-2level", ...
I am putting together a Samba-based server as a Primary Domain Controller, and ran into a cute little problem that should have been solved many times over. But a number of searches did not yield a result. I need to be able to remove an existing user from an existing group with a command line script. It appears that the usermod easily ...
I am seeing both of them used in this script I am trying to debug and the literature is just not clear. Can someone demystify this for me? ...
Can someone suggest a good module in perl which can be used to store collection of objects? Or is ARRAY a good enough substitute for most of the needs? Update: I am looking for a collections class because I want to be able to do an operation like compute collection level property from each element. Since I need to perform many such op...
Can someone explain what exactly the string "0 but true" means in Perl? As far as I understand, it equals zero in an integer comparison, but evaluates to true when used as a boolean. Is this correct? Is this a normal behavior of the language or is this a special string treated as a special case in the interpreter? ...
Does a hash shrink in Perl as you delete elements. More specifically I had a perl program that I inherited that would parse a huge file ( 1 GB ) and load up a hash of hashes. it would do that same for another file and then do a comparison of different elements. The memory consumption was huge during this process and even though I added...