The document discusses advanced Perl modules, specifically how they can function both as standalone programs and reusable components. It illustrates various examples of defining and running a 'hello world' program, including unit testing techniques using the Test::More module. Additionally, it covers the implementation of command-line arguments and object-oriented structures in Perl applications.

1. Advanced
Modulinos
★ brian d foy
The Perl Review
Houston Perl Mongers

2. Files that work as
programs and modules
at the same time

3. Unit testing
Code reüse
Distribution

4. # hello.pl
use v5.10;
say 'Hello World!';

5. % perl hello.pl
Hello World!

6. use v5.10;
run();
sub run {
say 'Hello World!';
}

7. % perl hello.pl
Hello World!

8. # Hello.pm
use v5.10;
run() unless caller;
sub run {
say 'Hello World!';
}

9. % perl hello.pl
Hello World!
% perl -MHello -e 1
%

10. package Hello;
use v5.10;
__PACKAGE__->run
unless caller;
sub run {
say 'Hello World!';
}

11. use Test::More;
use Test::Output;
use_ok( 'Hello' );
stdout_ok(
sub { Hello->run() },
'Hello World!', ...
);

12. package Hello;
use v5.10;
__PACKAGE__->run
unless caller;
sub run {
my( $self ) = @_;
say { $self->fh }
'Hello World!';
}

13. package Hello;
use v5.10;
...;
sub fh { *STDOUT }

14. use Test::More;
use_ok( 'Hello' );
our $string;
{
open my $fh, '>', $string;
*Hello::fh = sub { $fh };
}
Hello->run;
is($string, 'Hello World!');

15. package Hello;
use v5.10;
...;
BEGIN {
my $fh = *STDOUT;
sub fh { $fh }
sub set_fh {
$fh = ...;
}

16. use Test::More;
use_ok( 'Hello' );
open my $fh, '>', my $string;
Hello->set_fh( $fh );
Hello->run;
is($string, 'Hello World!');

17. % perl hello.pl
Hello World!
% perl hello.pl Houston
Hello World!
% perl hello.pl -m Texas
Hello World!
% perl hello.pl < partiers
Hello World!

18. Connect the
command line to new()
% hello.pl -s Houston
?
use Hello;
new()
my $app->new(
input => $in_fh,
output => $out_fh,
message => $message,
);
$app->greet;

19. sub run {
my( $class, @args ) = @_;
my %args =
$class->process_args(@args);
my $self = $class->new(%args);
say { $self->fh }
$self->message;
}

20. sub process_args {
require Getopt::Std;
local @ARGV = @_;
getopts('oim:', my %opts);
$opts('o') //= *STDOUT;
$opts('i') //= *STDIN;
$opts('m') //= 'Hello World!';
# left over @_?
my %args = map {
$opts_map{$_} => $opts{$_}
} keys %opts;
}

21. $app->new(
input_fh => $in,
output_fh => $out,
message => 'Hello World!'
);

22. sub new {
my( $class, %args ) = @_;
my $self = bless {}, $class;
foreach ( keys %args ) {
# maybe more complicated
$self->set( $_, $args{$_} );
}
return $self;
}