On Fri, Mar 25, 2005 at 08:32:13AM -0000, Rafael Garcia-Suarez wrote:
> Autrijus Tang wrote in perl.perl6.compiler :
> > Consider this program, example.p6:
> >
> > use v6;
> > my $var = BEGIN { say "I'm compiling, man"; time() }
> > say "Compiled at { time() - $var } seconds ago!";
> >
> > Is this behaviour correct?
> >
> > % pugscc --parrot example.p6
> > I'm compiling, man
> > % sleep 60
> > % parrot example.pmc
> > Compiled at 60 seconds ago!
>
> It looks not correct to my perl 5 trained eyes.
> BEGIN is designed to let things run as early as possible, mostly
> for Perl programs to discover things about the environment they're
> running in. That's a different environment than the environment they
> were compiled in. For example :
>
> my $use_debug_mode = BEGIN { %*ENV{DEBUGME} ?? 1 :: 0 };
>
> On the other hand there are CHECK blocks too.
The pugs behaviour is consistent with Perl 5's byte compiler/ByteLoader:
$ cat sleeper
my $var;
BEGIN { print "I'm compiling, man\n"; $var = time(); };
print "Compiled at @{[ time() - $var ]} seconds ago!\n";
__END__
$ ~/Reference/5.8.1/bin/perl5.8.1-32 ~/Reference/5.8.1/bin/perlcc5.8.1 -B
sleeper
$ sleep 60
$ ~/Reference/5.8.1/bin/perl5.8.1-32 a.out
Compiled at 65 seconds ago!
If anyone wants to play with it, please note that the Perl 5 ByteLoader is
"experimental", not always reliable by 5.8.1, definitely not efficient, and
I think inadvertently broken from 5.8.3 or so onwards. Bug reports on it are
interesting, but fixing it isn't a priority. (Limited volunteer resources,
hard problem, and plenty of other things that can be done that are a better
use of time and enthusiasm)
Nicholas Clark
