comment on

The thing about Moose is that it isn't really addressing the issue that the OP cited -- that the "default" approach to objects in Perl 5 is blessing a hash and storing attributes in the hash -- as it doesn't address the encapsulation and substitutability issues (what has come to called "foreign inheritance" by inside-out authors).

Moose is built with Class::MOP, which provides some nice sugar, but doesn't really change the underlying behavior. From the description of Class::MOP:

This module is an attempt to create a meta object protocol for the Perl 5 object system. It makes no attempt to change the behavior or characteristics of the Perl 5 object system, only to create a protocol for its manipulation and introspection.

What it does well is to allow for various types of introspection. (See stvn's response to my question about this in another thread.) This is very helpful for object-relational mapping like DBIx::Class and (I'd imagine) request-dispatch mapping frameworks like Catalyst. The fact that Moose is proving useful to these applications doesn't mean that it's well suited for all types of problems. (It doesn't mean that it isn't, either.)

And while it might be possible to build inside-out objects using Class::MOP, the InsideOutClass example bundled with it has substantial missing pieces and is currently YABIOOI (yet another broken inside-out object implementation). When I have enough tuits, I might tackle a proper inside-out implementation using Class::MOP.

I have great respect for stvn, and I'm glad to see some of the insights from the Perl 6 object system migrating back to Perl 5, but I don't think that Class::MOP or Moose really address the underlying issues that the OP was asking about -- though they do bring some useful systematization to Perl OO techniques and make it easier to address the problems that exist today.

For that matter, it should be noted that inside-out objects aren't a panacea, either. They solve a couple of problems, but at the cost of a substantial increase in complexity.

It's all the more reason to look forward to Perl 6.

-xdg

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In reply to Re^2: Perl 5 OOP solutions by xdg
in thread Perl 5 OOP solutions by tomazos

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