> perl -MAcme::Everything -le 'print Math::GMP->new(42);'
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#!/usr/bin/perl -l
# Use a CPAN module that is *not* installed! Is this a good idea?
# Posted to perlmonks.org by an Anonymous Monk on Sun Jun 17 2018
#
# In this example, if the Astro::MoonPhase module is not installed,
# the use_cpan sub will parse the error, download the module page 
# from metacpan, parse that for the source code uri, download the
# raw module source, eval that string, and proceed normally as if 
# the module was installed! It does not work with all modules and 
# the concept is presented to the Monastery for contemplation.
#__QKB__
# Hacked by usemodperl: use Carp. Added module cache.

use strict;
use warnings;
use Carp 'croak';

eval { require Astro::MoonPhase };
use_CPAN($@) if $@;

my @phases = Astro::MoonPhase::phasehunt();
print q~LOCALTIME     = ~, scalar localtime time;
print q~New Moon      = ~, scalar localtime $phases[0];
print q~First quarter = ~, scalar localtime $phases[1];
print q~Full moon     = ~, scalar localtime $phases[2];
print q~Last quarter  = ~, scalar localtime $phases[3];
print q~New Moon      = ~, scalar localtime $phases[4];

sub use_CPAN
{
    local ($_) = @_;
    if (/install the (\S+) module/) {
         my $module = $1;
         my $moddir = '.perlmod';
        (my $modloc =  $module) =~ s/::/__/g;
            $modloc = "$moddir/$modloc";

        if (-d $moddir and -e $modloc) {
            open my $fh, '<', $modloc or croak "$!";
            @_ = <$fh>; close $fh; 
            $_ = join "\n", @_;
            eval $_ or croak;
        }
        else {
            require HTTP::Tiny;
            $_ = HTTP::Tiny->new->get("https://metacpan.org/pod/$modul
+e");
            croak unless $_->{content};

            for ($_->{content} =~ /Source<\/a>\s*\(<a href="([^"]+)">r
+aw/) {
                $_ = HTTP::Tiny->new->get($1);
                $_ = $_->{content} ? $_->{content} : croak;
                eval $_ or croak;
                eval mkdir $moddir; croak $@ if $@;
                if (open my $fh, '>', $modloc or croak "$!") {
                    print $fh $_; close $fh;
                }
                last
            }
        }
    }
}
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