Re: To :D or not to :D
[email protected] (Mark Overmeer)
| Newsgroups | perl.perl6.language |
|---|---|
| Organization | MARKOV Solutions |
| Message-ID | <[email protected]> |
* Moritz Lenz ([email protected]) [151012 15:32]: > > . are they using :D correctly? > > Yes, though not everybody uses :D as much as they do. Do you check that > all the parameters that your Perl 5 methods/subs receive are defined? If > not, you wouldn't use :D in Perl 6 either. In Perl5, you get slower code when you test for definedness... in Perl6 you get faster (better optimized) code. That's a big difference. > FWIW you can now (as of a few days ago) control the default with > use invocant :D; How can de invocant not be defined? > use parameters :D; The new "use warnings"/"use strict"... > which means all those :D annotations can go away, and you have to use :_ > explicitly if you want to allow all. Oh, use :U for that. Ehhh.... already in use. > That said, I agree that it's the wrong default. And the design documents > even mandate a default to :D, though at the time it was written, it > wasn't clear how to switch off that default, nor how to avoid having to > write > > method new(MyClassHere:U: *@args) { ... } > > in the constructor, which would be quite hostile to newbies. It's still > not clear to me how to avoid that. It is also unclear to me what this means. It is a method which requires and undef parameter? > And I don't know if we can change it now without creating a huge havoc > in the existing ecosystem. There shouldn't be a problem making :D a superfluous option. Of swiftly add "use parameters $_;" to all modules. And there still quite a number of other crucial changes going in anyway... > Another concern is that if "everything" defaults to :D, then classes > (and other type objects) aren't really first class objects anymore, > which is a really neat thing to have. Can you give me an example? Many other languages are capable to live without undef and have first class type objects. In the old days, I had to implement the Algol68 style during compile construction course ;-) > > . :D looks really ugly, don't you think? Try to explain to students > > to add this smiley everywhere. > > It's not uglier than a 'die "Must be defined" unless defined $x' Much too expensive in Perl5. -- Regards, MarkOv ------------------------------------------------------------------------ Mark Overmeer MSc MARKOV Solutions [email protected] [email protected] http://Mark.Overmeer.net http://solutions.overmeer.net