I have been studying OOP and Moose.

I stumbled upon the RJBS presentation https://cdn.oreillystatic.com/en/assets/1/event/115/Moose%20is%20Perl_%20A%20Guide%20to%20the%20New%20Revolution%20Presentation%202.pdf "Moose is Perl".

I find it instructive to write Perl 5 programs showing each example found in presentations, blogs, and tutorials.

Here is one:

Perl 5 program: mip-087-001.pl

#!/usr/bin/perl

# Program name: mip-087-001.pl  Run it, thusly: See C++ comment below.
+  Moose is Perl (i.e., MIP or mip) presentation.

# From https://cdn.oreillystatic.com/en/assets/1/event/115/Moose%20is%
+20Perl_%20A%20Guide%20to%20the%20New%20Revolution%20Presentation%202.
+pdf.

# The code below is from https://www.perl.com/pub/2002/08/13/comment.h
+tml/

use Acme::Comment type => 'C++', one_line => 1, own_line => 0;

/*
cd C:\2020-Raku-001\
perl C:\2020-Raku-001\Perl-scripts\mip-087-001.pl
*/

use strict;
use warnings;
use feature 'say';
local $| = 1;    # Forces a flush.

package Employee {

use strict;
use warnings;

use Moose;
use namespace::autoclean;  # Code this instead of coding "no Moose;" a
+t the end of the package block.

has name  => (
  is       => 'ro',
  isa      => 'Str',
  required => 1,
);
has title => (
  is       => 'rw',
  isa      => 'Str',
  required => 1,
);

sub name_and_title {
  my ($self) = @_;

  my $name  = $self->name;
  my $title = $self->title;

  return "$name, $title";
}
1;  # Magic true value.
}

package Employee::Former {

use strict;
use warnings;

use Moose;
use namespace::autoclean;  # Code this instead of coding "no Moose;" a
+t the end of the package block.

extends 'Employee';

override name_and_title => sub {
  my ($self) = @_;
  my $old = super;
  return "$old (Former)";
};

# Slide #85.
# The + says "we're overriding the definition in our superclass.  Ever
+ything stays the same 
# except for the provided changes."

# Here, we give a default.  If no value is given, the default is used,
+ which lets us satisfy the 
# "required" even when no value was given in the call to the construct
+or.

has '+title' => (
  default => 'Team Member',
);
1;  # Magic true value.
}

# Commented out.  use Employee;
my $peon = Employee->new({
  name  => 'William Toady',
  title => 'Associate Assistant',
});

say $peon->name_and_title;  # Get name_and_title.

# Commented out.  use Employee::Former;
my $ex_peon = Employee::Former->new({
  name  => 'William Toady',
  title => 'Associate Assistant',
});

say $ex_peon->name_and_title;  # Get name_and_title.

# Where is the test code?  Answer: Slide #87.
# Name this script mip-087-001.pl

my $ex_peon2 = Employee::Former->new({
  name  => 'William Toady',
});

say $ex_peon2->name_and_title;  # ===> William Toady, Team Member (for
+mer)

__END__
[download]

Results:

William Toady, Associate Assistant
William Toady, Associate Assistant (Former)
William Toady, Team Member (Former)
[download]

I recently looked at Raku after the name change. (The Windows version is actually easy to install now.)

So, after reading much of the "Think Raku" book, I tried to write counterparts to my collection of Perl 5 RJBS presentation "Moose is Perl" programs.

Well,I am stuck. (I thought Moose was 1:1 Raku OOP. Boy, was I wrong.)

Raku program attempt: mip-087-001.raku

class Employee {
  has Str $.name  is readonly is required;  # "readonly" is the defaul
+t.
  has Str $.title is rw       is required;
  
  method name_and_title {

  my $name  = self.name;
  my $title = self.title;

  return "$name, $title";
  }
}


class Employee::Former is Employee {
  
  method name_and_title {
  
    my $old = callsame;
  
    return "$old (Former)";
  }

# Slide #85.
# The + says "we're overriding the definition in our superclass.  Ever
+ything stays the same 
# except for the provided changes."

# Here, we give a default.  If no value is given, the default is used,
+ which lets us satisfy the 
# "required" even when no value was given in the call to the construct
+or.

# XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
# Is there not a Raku counterpart for this?
# has '+title' => (
#   default => 'Team Member',
# );
# My poor attempt:
  has $.title is default('Team Member');
# XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
}

# Commented out.  use Employee;
my $peon = Employee.new(
  name  => 'William Toady',
  title => 'Associate Assistant',
);

say $peon.name_and_title;  # Get name_and_title.

# Commented out.  use Employee::Former;
my $ex_peon = Employee::Former.new(
  name  => 'William Toady',
  title => 'Associate Assistant',
);

say $ex_peon.name_and_title;  # Get name_and_title.

# Where is the test code?  Answer: Slide #87.
# Name this script mip-087-001.raku

my $ex_peon2 = Employee::Former.new(
  name  => 'William Toady',
);

say $ex_peon2.name_and_title;  # ===> William Toady, Team Member (form
+er)
[download]

Results:

William Toady, Associate Assistant
William Toady, Associate Assistant (Former)
The attribute '$!title' is required, but you did not provide a value f
+or it.
  in block <unit> at C:\2020-Raku-001\Raku-scripts\mip-087-001.raku li
+ne 60
[download]

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