#!/bin/bash
declare -x PLV_STRING
function perl_v_in_use
{
  # contrast with use of version pragma as in:
  #   $ perl -le 'use version 0.77; print version->parse($])->normal'
  /usr/bin/env perl \
    -e 'my $pow = 2; @qiu = split(q/[.]/=>$]);' \
    -e '@qiu[1 .. @qiu] = map{sprintf(q[%u],$_/10**$pow++)} ' \
    -e 'map {unpack "A4 A4",$_ * 10**3 } @qiu[1 .. $#qiu];' \
    -e 'print join q[.], grep{length($_)} @qiu;'
}

function pviu_insurance
{
    by_longhand="$(perl_v_in_use)"
    if [[ "v$by_longhand" == $(/usr/bin/env perl -e 'print $^V') ]]
        then return 0
    else     return 1
    fi
}

function set_perl_v_in_use
{
    if pviu_insurance
        then PLV_STRING=$(perl_v_in_use)
        else printf >&2 "WARNING: NON-SUCCESS rv \"%u\" from pviu_insurance\n" $?
             PLV_STRING='0_INVALID'
    fi
}