Blessing into the same package in class (object) and tie contexts

ryangies has asked for the wisdom of the Perl Monks concerning the following question:

I find myself using this pattern a lot, and I'm not sure of two things: 1) Is this standard operating procedure and there is a name for it? 2) Is it forward compatible, going to work in perl6? All I'm doing is blessing a reference in the subroutine, "new" and then tying that blessed thingy to the same package. Example, "MyPackage.pm"

package MyPackage;
use strict;
our $VERSION = 0;

use Tie::Hash;
use base qw(Tie::ExtraHash);

# OO Interface

sub new {
  my $class = ref($_[0]) || $_[0];
  my $self = bless {}, $class;
  tie %$self, $class;
}

sub to_string { join ' ', %{$_[0]}; }

# Tie interface

sub STORE { $_[0][0]{$_[1]} = ucfirst($_[2]); }

1;
[download]

Example, "t-mypackage.pl" which uses "MyPackage.pm"

#!/usr/bin/perl -w
use strict;
use MyPackage;

my $p = MyPackage->new();
$$p{Hello} = "world";
print $p->to_string, "\n";
[download]

Comment on Blessing into the same package in class (object) and tie contexts Select or Download Code

Replies are listed 'Best First'.
Re: Blessing into the same package in class (object) and tie contexts by Arunbear (Prior) on Mar 27, 2008 at 21:28 UTC
This is not standard operating procedure, as far as I know. `my $p = MyPackage->new(); $$p{Hello} = "world"; print $p->to_string, "\n";` [download] Requiring users of MyPackage objects to know that the objects are hashrefs isn't good OO (no encapsulation). And dereferencing the hashref to use it as a tied hash seems convoluted and unnatural e.g. compared to an interface like `tie my %h, MyPackage; $h{Hello} = "world"; # use tied to call object methods print tied(%h)->to_string, "\n"; # -> 'Hello World'` [download] i.e. in the example you've given there doesn't seem to be a case for going beyond the standard tied hash semantics.	[reply] [d/l] [select]
Re^2: Blessing into the same package in class (object) and tie contexts by ryangies (Initiate) on Mar 28, 2008 at 02:05 UTC
I suspected this was not common and appreciate the validation. I have run in to a few stack dumps with different variations on this theme and am concerned that there might be a critical no-no which I'm unaware of. Read more... (677 Bytes)	[reply] [d/l]
Re: Blessing into the same package in class (object) and tie contexts by ikegami (Patriarch) on Mar 27, 2008 at 18:17 UTC
Why use `(ref($_[0]) \|\| $_[0])` in one place and `__PACKAGE__` in the other? `sub new { my $class = (ref($_[0]) \|\| $_[0]); my $self = bless {}, $class; tie %$self, $class; $self }` [download]	[reply] [d/l] [select]
Re^2: Blessing into the same package in class (object) and tie contexts by ryangies (Initiate) on Mar 27, 2008 at 18:42 UTC
Oops, thank you, I updated the post.	[reply]