* 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
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