Let's assume you have a recent Perl and CPANPLUS installed. You want your brand new script to automatically install any modules that are not found. Well, maybe you don't. I'm sure I don't, but I couldn't resist the temptation and made Blah.pm. The module name describes exactly what it does, or... no it doesn't... but I needed a name.

My first try had a $SIG{__DIE__} handler and die "Try again :)\n", but it still didn't look nice. I did this because you cannot resurrect scripts. Kane had the idea of using exec($^X, $0, @ARGV) instead, which worked perfectly. But then, lathos suggested using a code ref in @INC. With the help of this node, I created this:

Blah.pm

use strict;
use CPANPLUS;

push @INC, sub {
    my ($code, $file) = @_;
    my $module = $file;
    $module =~ s!/!::!g;
    $module =~ s!\.pm$!!g;
    install($module);
    for (@INC) {
        next if ref;
        if (-e "$_/$file" and -r _) {
            open my $fh, '<', "$_/$file" or die $!;
            return $fh;
        }
    }
    return undef;
};
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Please note that real programmers don't use CPANPLUS but CPANPLUS::Backend, and use the great backend. I was lazy and used CPANPLUS with the simple install() function, but that is bad.

Example script:

use Blah;
use Acme::Time::Baby;
print babytime(), "\n";
[download]

Example output:

3;0 root@ouranos:/home/juerd/modtest# perl test.pl
Checking if your kit is complete...
Looks good
Writing Makefile for Acme::Time::Baby
PERL_DL_NONLAZY=1 /usr/bin/perl -Iblib/arch -Iblib/lib -I/usr/lib/perl
+/5.6.1 -I/
usr/share/perl/5.6.1 -e 'use Test::Harness qw(&runtests $verbose); $ve
+rbose=(eva
l(chr(36).q(|=1))-1); runtests @ARGV;' t/*.t
t/00_en..........ok
t/01_du..........ok
t/02_custom......ok
t/03_noimport....ok
t/04_chef........ok
t/05_warez.......ok
t/06_de..........ok
t/07_fr..........ok
t/08_no..........ok
t/09_it..........ok
All tests successful.
Files=10, Tests=12972,  6 wallclock secs ( 2.33 cusr +  0.17 csys =  2
+.50 CPU)
Installing of Acme::Time::Baby succesfull
The big hand is on the eight and the little hand is on the ten
3;0 root@ouranos:/home/juerd/modtest# perl test.pl
The big hand is on the nine and the little hand is on the ten
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- Yes, I reinvent wheels.
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