use strict; use warnings;
my %options;
BEGIN {
    use Getopt::Std;
    getopt('v', \%options);
    die "invalid value for -v switch\n"
        if ($options{v} !~ /^(?:7|8)$/);
    my $path = "/path/for/v$options{v}/lib/perl5";
    unshift @INC, $path;
}   
use Infoblox; # /path/for/v$options{v}/lib/perl5 will be searched first