Perl version and environment matrix

---

examples/perl-env-version-matrix/.travis.yml

language: perl
perl:
   - "5.30"
   - "5.28"

env:
    - DEMO=Alpha
    - DEMO=Beta

matrix:
  exclude:
  - perl: "5.28"
    env: DEMO=Beta

examples/perl-env-version-matrix/Makefile.PL

use strict;
use warnings;
use ExtUtils::MakeMaker;

for my $key (sort keys %ENV) {
    print "$key=$ENV{$key}\n";
}

WriteMakefile(
    NAME         => 'Project',
    AUTHOR       => q{Gabor Szabo <szabgab@cpan.org>},
    VERSION      => '0.01',
    ABSTRACT     => 'Demo Perl Makefile.PL',
    ( $ExtUtils::MakeMaker::VERSION >= 6.3002
        ? ( 'LICENSE' => 'perl' )
        : () ),
    PL_FILES  => {},
    PREREQ_PM => {
    },
    dist  => { COMPRESS => 'gzip -9f', SUFFIX => 'gz', },
);