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A comment on Damian Conway on Perl and its future. Parent comment

Re:Damian Conway on Perl and its future by berntb on Tuesday May 25, 2010 @09:17AM (#1377307)
I found out something that makes life on HN better.

To avoid the [language war] trolls in stories about Perl, I mention Moose.

Since it is a better OO system than anything in the competition, they generally go away... :-)

Edit: I really wish Lisp was the competition today, I always loved it. :-( I've never used CLOS, but afaik Moose is directly inspired by it (MOP, right?).

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by loewenskind on Tuesday May 25, 2010 @09:22AM (#1377318)
Anything in the competition, like say, CLOS? But I'll grant you that Moose is better than what a lot of other languages offer.
[ Parent | on HN ]
Re:Damian Conway on Perl and its future by draegtun on Tuesday May 25, 2010 @09:30AM (#1377336)
Moose is heavily inspired by CLOS and its borrowed features from it including having it built on top of a meta-circular MOP: http://search.cpan.org/dist/Class-MOP/

You may find this Perlmonks discussion interesting, especially "stvn" comments: http://www.perlmonks.org/?node_id=655788

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by sreque on Tuesday May 25, 2010 @12:42PM (#1377868)
I'll trollishly bite. I just read http://search.cpan.org/~flora/Moose-1.05/lib/Moose/Manual/Co.... While it does look like a good library that I'd be interested in learning if I'm ever forced to code Perl for monies again, I don't see anything special in it that isn't in other languages or couldn't be implemented in them as a library.
[ Parent | on HN ]
Re:Damian Conway on Perl and its future by berntb on Wednesday May 26, 2010 @07:51AM (#1380058)
Sorry for being irritated in the other comment, you obviously asked serious questions out of interest. I'll try to not let the trolling whenever Perl is mentioned to get under my skin in the future.

(On the other hand, you got a better answer than from me when Chromatic answered. :-) )

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by berntb on Tuesday May 25, 2010 @02:07PM (#1378085)
Please see draegtun's references, re MOP. (You don't like mixins in Role form? Ah, never mind -- I have real work to do.)
[ Parent | on HN ]
Re:Damian Conway on Perl and its future by sreque on Tuesday May 25, 2010 @02:19PM (#1378113)
What does Moose's mixins in role form give you over Ruby's mixins, or Scala's mixins, or PLT-Scheme's mixins, or just simulating mixins via a multiple-inheritance hierarchy ala Python or C++? I'm not going to spend a ton of time researching, but from what I see at links like http://search.cpan.org/~flora/Moose-1.05/lib/Moose/Manual/Ro..., it seems like a nice idea but it's certainly been done before and since in other languages. A lot of the features like method exclusion and aliasing or required host methods could easily be implemented in a library on top of your favorite dynamic language as well if they don't include them natively.

The MOP looks like a necessary tool for Perl's horribly designed OO that wouldn't be necessary for most other languages or could just as easily be implemented as a library. Python and Ruby both have what seems to be the equivalent of metaclasses. Most OO languages have some idea of what an attribute is. And so on. Once again, MOP looks neat, but it's certainly not unique to Moose.

edit: reading the MOP link more carefully, the idea of a class builder builder is more sophisticated than I originally thought MOP was, but as the link says, you're heading into esoteric territory at that point.

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by chromatic on Tuesday May 25, 2010 @04:51PM (#1378575)
What does Moose's mixins in role form give you over Ruby's mixins, or Scala's mixins, or PLT-Scheme's mixins, or just simulating mixins via a multiple-inheritance hierarchy ala Python or C++?

Safety and correctness.

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by sreque on Tuesday May 25, 2010 @05:56PM (#1378767)
Not sure what you mean. In Ruby, for instance, whenever a module is mixed in a hook method on the module is called. You can enforce any safety or correctness constraints on the parent class that you want at that point. You can easily imagine writing a library in ruby that lets you do the same things as in Moose in terms of correctness and safety. Similarly, you could write your own 'include' method that took extra parameters and performed the same mixin magic Moose is doing like excluding or aliasing methods, performing special handling of conflicting methods, etc.

My main point in all this is that, from my perspective, Moose may have a few bells and whistles beyond the base OO features of other dynamic languages, but these features are more 'nice to haves' than 'essentials. More importantly, these features could also be trivially added in other languages as libraries. Most importantly of all, none of these features is as important as starting out with a clean, well-designed language in the first place, and Perl is anything but clean or well-designed.

[ Parent | on HN ]
Re:Damian Conway on Perl and its future by chromatic on Tuesday May 25, 2010 @06:35PM (#1378867)
Not sure what you mean.

Duck typing suffers from the false cognate problem, and mixins suffer from false cognates and potential collisions. They also do nothing to ensure type safety or optional type-based compile-time optimizations.

More importantly, these features could also be trivially added in other languages as libraries.

Non-Moose Perl 5, Tcl, Lisp-pre-CLOS, Lua, and JavaScript to some extent demonstrate the "you can roll your own object system trivially!" fallacy, especially when you want to use libraries written by other people. Likewise, I'm not aware of anyone who's used roles in a serious project who wants to go back to object systems without them.

[ Parent | on HN ]