Perl 5 OOP programming

Question

I'm trying to port the following python program to perl5:

import numpy as np


class Hensuu:
    def __init__(self, data):
        self.data = data


class Kansuu:
    def __call__(self, input):
        x = input.data
        y = x ** 2
        output = Hensuu(y)
        return output

x = Hensuu(np.array(9.0))
f = Kansuu()
y = f(x)

print(type(y))
print(y.data)

main.Hensuu'> 81.0

Hensuu.pm

package Hensuu;
use strict;
use warnings FATAL => 'all';
our $version = 1.0.0;
sub new {
    our ($class,$data) = @_;
    my $self = {data=>$data};
    bless $self,$class;
    return $self;
}
1;

step1.pl

#!perl
use strict;
use warnings FATAL => 'all';
use Hensuu;
use PDL;
use PDL::Matrix;
my $datas = mpdl [[1.0,2.0],[3.0,4.0]];
my $x = Hensuu->new($datas);
print($x=>$datas);

Kansuu.pm

package Kansuu;
#use strict;
use warnings FATAL => 'all';
use Hensuu;
sub call {
    my ($self,$input) = @_;
    my $x = {$input => $data};
    #print($x);
    my $y = $x ** 2;
    my $output = Hensuu->new($y);
    return($output);
}
1;

step2.pl

#!perl
#use strict;
use warnings FATAL => 'all';
use PDL;
use PDL::Matrix;
use Hensuu;
use Kansuu;

my $a = mpdl [9.0];
my $x = Hensuu->new($a);
#my $f = Kansuu;
#my $y = $f->call($x);
my $y = Kansuu->call($x);
print($x=>$a);
print(ref($y));
print($y);

emit(step2.pl)

Hensuu=HASH(0x1faf80)
[
 [9]
]
HensuuHensuu=HASH(0x25b71c0)
Process finished with exit code 0

The above program (step2.pl), I want to set the display to "81" with print($y) ;, but I can't. Environment is Windows 10 pro, strawberry perl PDL edition (5.32.1.1), The IDE is intellij idea community edition perl plugin (2020.3).

user_1030675 · Answer

Hensuu.pm:

package Hensuu;
use strict;
use warnings;

sub new {
    my ($class, $data) = @_;
    return bless {data => $data}, $class
}

sub data {
    my ($self) = @_;
    return $self->{data}
}

1

Kansuu.pm:

package Kansuu;
use strict;
use warnings;

use Hensuu;

sub call {
    my ($input) = @_;
    my $x = $input->data;
    my $y = $x ** 2;
    my $output = Hensuu->new($y);
    return $output->data
}

1

step2.pl:

#!perl
use strict;
use warnings;
use feature qw{ say };

use PDL;
use PDL::Matrix;
use Hensuu;
use Kansuu;

my $p = mpdl [9.0];
my $x = Hensuu->new($p);
my $y = Kansuu::call($x);
say $y;

Don't use our variables for things that don't need to be global.
Don't use $a as a lexical variable, it's a special variable used in sort.
Low level Perl OO doesn't create accessors for attributes, you need to implement them yourself (see Moo or Moose for higher level ways).
Kansuu is not an OO class, use a fully qualified subroutine instead of a method.

Perl 5 OOP programming

<class 'main.Hensuu'> 81.0

1 Answers