On demand PDL::PP via Inline and string eval

on_demand_pdlpp.pl

#!/usr/bin/env perl

use strict;
use warnings;

use PDL;

my $cond = shift || 0; # can pass a true value as an arg to the script
my $pdl = null();

# sometime later
if ($cond)
{
    eval <<'STRING_EVAL';
warn "Compiling";
use Inline Pdlpp => << 'PDLPP';
pp_def('say_hi',
    'Pars' => 'a(n)',
    'Code' => q{ printf("%s\n", "Hello, world!"); }
);
PDLPP
STRING_EVAL
    $pdl->say_hi();
}