--- Larry Wall <[EMAIL PROTECTED]> wrote:
> Well, it's not nearly as general as we're making it, but the
> inspiration for it comes in part from the "Traits" paper:
>
> http://www.cse.ogi.edu/~black/publications/TR_CSE_02-012.pdf
>
> Basically, I'm attempting to take their concept and unify it with
> properties, interfaces, generics, aspects, and mixins. Among other
> things...
Ok, having read this now (at least corsorily) and compared it with what I
believe I understand about the way P6 is implementing
traits/properties/roles, I begin to get it, and I am, as usual, suitably
impressed and excited.
So is this a good time to divert this topic into an elaboration of roles?
> : Somebody drop me an example?
>
> Well, it hasn't been defined yet. Likely there will be some syntax
>
> my property foo;
>
> that is shorthand for something vaguely resembling
>
> my role foo is property {
> has $.foo is rw;
> }
So if I want to implement a package of related roles that I commonly use in
our In-House code, such as to specify how verbose an object should be on log
output, and how touchy it should be over whether a problem is screamingly
fatal or just warningly annoying, and maybe toss in a shorthand method that
lets me pass the names of some specific traits I want to be able to use (
like "allow(qw/winkin blinkin nod/)" or some such), it should be pretty
simple....but I'm having a hard time coming up with the syntax that declares
the package and exports the roles.
module IHL::Roles;
@ISA = 'Exporter';
@EXPORT_OK = qw/ fatal verbose allow setvals /;
our role fatal is property {
has $.fatal is rw;
}
our role verbose is property {
has $.verbose is rw;
}
sub allow {
.... # I'd want to make this one too complex to actually do it here
}
sub import {
allow @_[1...];
}
sub setvals ($o, [EMAIL PROTECTED]) {
"\$o.$_ = true".eval for @t; # surely there's a better way to do this?
}
then write allow() to build roles for each value passed in, maybe taking an
arg to say whether they should be truly global, or built in the caller's
namespace....
Then I could say
use IHL::Roles qw/ allow setvals fatal verbose /;
use Foo;
my $o = Foo.new();
allow qw/ foo bar baz /;
setvals($o,qw/ verbose baz /);
I'm trying to make sure I don't tumble back into pure P5 here, but I don't
think I'm really awake yet. :)
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