This just went up in my blog, but I think it's interesting enough to post
to the list as well.
-jeff
One of the goals of the mod_parrot project is to provide the
infrastructure for running the Perl 6 version of mod_perl, a.k.a.
mod_perl6. I've already demonstrated that mod_perl6 works, so that goal is
slowly being achieved. Many thanks to Patrick Michaud, Jerry Gay, and
everyone else who has worked on the Parrot implementation of Perl 6.
Another lesser known goal of mod_parrot is to allow the high level
language (HLL) layers to be written in the HLL itself. That is to say,
write mod_perl6 in Perl 6. Up to this point, mod_parrot has five HLL
layers (PIR, NQP, Perl6, PHP/Plumhead, Perl1/Punie), all written in
Parrot's native PIR. However, yesterday, with some help from Patrick, I
was able to port mod_perl6 from PIR to pure Perl 6!
As an example, here is a very bare-bones mod_perl6 (DISCLAIMER: string
interpolation in namespaces doesn't actually work yet):
module ModParrot::HLL::perl6;
our %loaded_modules;
# load a Perl 6 handler module
sub load($module)
{
unless (%loaded_modules{$module}) {
use $handler;
%loaded_modules{$module} = 1;
}
}
# call a Perl 6 response handler
sub handler($name)
{
my $r = Apache::RequestRec.new();
load($name);
my $status = ::($name)::handler($r);
$status;
}
# call a Perl 6 authentication handler
sub authen_handler($name)
{
my $r = Apache::RequestRec.new();
load($name);
my $status = ::($name)::handler($r);
$status;
}
When calling a Perl 6 handler, mod_parrot loads this module and calls the
individual handler routines according to the Apache configuration. It also
provides the interface to Apache, including the Apache::RequestRec class
needed by mod_perl6. Everything else it leaves to the Perl 6 compiler.
You might think this code doesn't actually do much, and that's the point.
It's really just a simple thunking layer between mod_parrot and your
handlers, enforcing the rules of the mod_perl6 implementation. For
example, in mod_perl, an Apache::RequestRec object is passed to all
response handlers. This layer is responsible for making sure that happens.
As the Perl 6 compiler matures and mod_parrot adds more functionality,
this version of mod_perl6 will inevitably change. But what you see above
will remain at its core -- loading Perl 6 modules, juggling arguments, and
passing control to handler subroutines. And the fact that it's pure Perl 6
will enable scores of Perl programmers to hack on it without having to
know anything about Parrot or C programming. Take that, XS.
