The Perl Short Questions Megathread: executable line noise

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heeen: May 14, 2005; CAT NEVER STOPS

^^ I think you don't even need do, wouldn't just curly brackets suffice?

a little gem I recently stumbled over:
How to sort a subset by a given ordered superset:

code:

#/usr/bin/perl -w
my @subset=('z','v','a','t');
my @ordered_total=(a..z);
print "$_," for (@subset);
print "\n";
print "$_," for (@ordered_total);
print "\n";


my %h; 
$h{ $_} = 1 for @subset;
my @ordered_sub = grep $h{ $_}, @ordered_total;


print "$_," for (@ordered_sub);
print "\n";

code:

z,v,a,t,
a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z,
a,t,v,z,

# ¿ Oct 30, 2007 19:15

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# ¿ Apr 30, 2024 04:59

heeen: May 14, 2005; CAT NEVER STOPS

by the way, this also works:

code:

perl -e 'print "$_\n" foreach(<*.*> );'

# ¿ Dec 18, 2007 18:54

heeen: May 14, 2005; CAT NEVER STOPS

Someone posted a module that, when ncluded, would change all string literals to pirate speak or something like that, does someone remember the link?

# ¿ Apr 3, 2008 18:34

heeen: May 14, 2005; CAT NEVER STOPS

how about

code:

$data[$i] = substr $input, $i*$col_width, ($i+1)*$col_width for my $i (1..160)
#or
@data = $input=~/(.{$col_width}){160}/ #or a precompiled regexp

# ¿ Apr 7, 2008 19:28

heeen: May 14, 2005; CAT NEVER STOPS

^^^ might look a bit hackish, but maybe ($col1, $col2, ..., $col160) performs faster?

I would really like to see a simple benchmark of the various methods posted so far, including the regexp. I think the regexp wouldn't perform too badly, since it gets compiled once at compile time and should be reasonably fast after that. If you build it with fixed length matches of any character it won't have backtracking or complicated matching cases.

# ¿ Apr 8, 2008 15:03

heeen: May 14, 2005; CAT NEVER STOPS

code:

SOAP::Data->name("pointHistory" => @credit_arr)

Even without knowing the package, this looks highly suspicious. sub parameters get coerced into flat arrays, which would lead to the following parameters passed to the sub:

code:

@_=("pointHistory", $credit_arr[0],  $credit_arr[1],  $credit_arr[2], ...)

which I'm quite certain the sub can't handle correctly. How does the sub know how many parameter elements belong to pointHistory and where the next hash key begins?
What the sub probably expects is:

code:

SOAP::Data->name("pointHistory" => \@credit_arr)

which it then can turn into a hash again.

# ¿ May 23, 2008 19:38

heeen: May 14, 2005; CAT NEVER STOPS

LightI3ulb posted:

Does anyone know of any modules that would allow me to receive mail and work with the attachments? The ones I've found on google are typically just for sending.

How do you define "receiving"? opening a port and listening to it? You're better off with letting a proper mail demon handling the receiving and a perl module reading a mbox file or Maildir frequently.

# ¿ May 23, 2008 19:40

heeen: May 14, 2005; CAT NEVER STOPS

Triple Tech posted:

So I want to call method from a super class that uses data defined in each sub class. Sort like...
code:
# object method

sub parse {
  my $self = shift;

  _munge($self::parameter);
}
Is this the way to go? Is my point clear enough? I don't even know if that example works of if it's even best practice. Obviously, the other way would be to just define shallow methods...
code:
sub parse {
  my $self = shift;

  _munge($self->getParameter);
}

What type is your object? blessed hashref? inside-out object?

# ¿ Jun 26, 2008 16:21

heeen: May 14, 2005; CAT NEVER STOPS

Triple Tech posted:

What's a compelling reason to use an INIT block versions just some code in main:: when making a module? My coworker says it's easier to tell how code in a module breaks if it's inside an INIT, versus main where it just says module use failed. I told him, you could see the error if you just ran the module as a script. Thoughts?

You put initializaton and unloading code into INIT, BEGIN and END blocks when you're writing scripts that get compiled once and then used precompiled, like FastCGI and PersistentPerl

edit: Irssi scripts, too.
edit: not necessarily irssi scripts, but I think I had a case once when I used it.

heeen fucked around with this message at 19:55 on Aug 14, 2008

# ¿ Aug 14, 2008 19:27

heeen: May 14, 2005; CAT NEVER STOPS

SubG posted:

What's the syntax for POSTing a multiple SELECT input via LWP::UserAgent?

If I remember correctly you have to submit foozle=>foo and foozle=>bar together.
wait, that doesn't work here...
try using an array instead of a hash:
$ua->post('http://some_url',[foozle=>'foo', foozle=>'bar']);

heeen fucked around with this message at 23:51 on Aug 22, 2008

# ¿ Aug 22, 2008 23:43

heeen: May 14, 2005; CAT NEVER STOPS

SpeedFrog posted:

To be honest I can't really see any reasonable use for wantarray().

I've seen this:

code:

sub getStuff()
{
my @foo;
.
.
.
return wantarray? @foo : \@foo;
}

how about :

return generateHugeListOf10_000_000elements() if wantarray;
return $numberof10_000_000elements;

heeen fucked around with this message at 18:57 on Aug 27, 2008

# ¿ Aug 27, 2008 18:49

heeen: May 14, 2005; CAT NEVER STOPS

Behold my palindrome test:

code:

use strict;
use warnings;
chomp (my $input = <> );
while($input=~/(.)(.*)\1/)
{
print "palindrome!\n" if length($2) <= 1;
$input=$2;
}

# ¿ Nov 11, 2008 12:03

heeen: May 14, 2005; CAT NEVER STOPS

whoops forgot to add start and end markers to the regexp.

code:

use strict;
use warnings;
chomp (my $input = <> );
while((undef,$input) = $input=~/^(.)(.*)\1$/)
{
print "palindrome!\n" if length($input) <= 1;
}

# ¿ Nov 11, 2008 15:12

heeen: May 14, 2005; CAT NEVER STOPS

code:

my %foo; #hash
$foo{name}="the dude";
my $ref=\%foo; #get a reference ("pointer") to %foo
print $ref->{name}; #the dude

my %bar;
$bar{name}="the girl";
$foo{girlfriend}=\%bar;

print $ref->{girlfriend}->{name}; #the girl
print $ref->{girlfriend}{name}; #only first arrow required

# ¿ Nov 21, 2008 15:55

heeen: May 14, 2005; CAT NEVER STOPS

Riddle me this: why does php outperform perl in this nsieve test twelve-fold:
http://shootout.alioth.debian.org/gp4/benchmark.php?test=nsieve&lang=perl&id=2
http://shootout.alioth.debian.org/gp4/benchmark.php?test=nsieve&lang=php&box=1
I converted the perl version from lists to strings like the php version, and it made it two seconds slower, so that can't be it.

# ¿ Apr 7, 2009 22:55

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# ¿ Apr 30, 2024 04:59

heeen: May 14, 2005; CAT NEVER STOPS

Triple Tech posted:

That implementation is gay. Looking at the C implementation, I'm going to assume these aren't out to prove how a certain data structure performs (array access), but to just solve the problem. You'd use a bit vector with vec(). (See Computing primes)

Edit: Ugh, who wrote that Perl submission. It's so different from the PHP one.

There's a seperate version with bitsets for each language.

# ¿ Apr 7, 2009 23:13

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