1. ★ Advanced
Modulinos
brian d foy
The Perl Review
YAPC::NA 2012

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. STDIN $0 STDOUT
@ARGV
%ENV exit code

7. Starting

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

9. % perl hello.pl
Hello World!
% perl -e 'require q(hello.pl)'
Hello World!

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

11. % perl Hello.pm
Hello World!
% perl -MHello -e 1
%

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

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

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

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

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

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

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

19. % perl hello.pl
Hello World!
% perl hello.pl Chicago
Hello World!
% perl hello.pl -m Rahm
Hello World!
% perl hello.pl < aldermen
Hello World!

20. 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;

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

22. 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;
}

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

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

25. Stopping

26. #!perl
...;
...;
...;
exit(0);

27. sub run {
my( $class, @args ) = @_;
my $object = eval {
...;
Result->new( code => 0 );
} or $@;
exit( $object->code );
}

28. sub some_sub {
...;
die
Result->new( code => 15 );
...;
}

29. sub run {
my( $class, @args ) = @_;
my $object = eval {
...;
Result->new( code => 0 );
};
exit( $error_object->code );
}

30. Testing

31. run() unless caller;

32. UNITCHECK {
if($ENV{TEST_HARNESS}){
__PACKAGE__->run_tests;
}
elsif( ! caller ) {
__PACKAGE__->run;
}
}

33. Docs

34. UNITCHECK {
if($ENV{TEST_HARNESS}){
__PACKAGE__->run_tests;
}
elsif($ENV{PERLDOC}){
__PACKAGE__->show_docs;
}
elsif( ! caller ) {
__PACKAGE__->run;
}
}