Re: [RFC] Switch to make Test::Builder output even if $^C ( for B::C )
Now I understand I missed to tell you this fundamental detail before,
sorry.
> perlcc seems to be dropping BEGIN blocks entirely, that's the problem.
No, that's correct. Explanation: if I have a module Foo
package Foo;
$x = 1;
print "AAA";
sub a { $x }
1;
and a main program foo.pl
BEGIN { # think use Foo;, expanded for clarity
require Foo;
}
print Foo::a();
perl -MO=C foo.pl
calls B::C::compile _after_ it ran the BEGIN blocks; this means that the optree in
Foo that initializes $x, and does "print AAA" has already been freed. So, even if
B::C could save BEGIN blocks, this
is not a good idea, for quite a lot of reasons.
> # foo.plx
> BEGIN {
> print "foo\n";
> }
> print "bar\n";
>
> $ bleadperl foo.plx
> foo
> bar
> $ perlcc foo.plx
> $ ./a.out
> bar
>
> The result from the compiled program should be the same as the
> original. For some reason the BEGIN block is getting dropped when the
> program is compiled. That's a bug.
It is not a bug that the BEGIN blocks are dropped. It is a B::C bug
induced by the perl design that it can't deal gracefully with code in
BEGIN blocks that print()s, or does other things to the "environment"
( OS, screen, disks, %ENV ), or that initializes data structures outside the scope of
perl ( this includes interpreter-local data using MY_CXT ( Opcode.pm ), or creating a
SV holding a pointer to an external data structure, or dup()s filehandles (
Test::Builder ) [1] ). The only solution to these problems is something like
B::Script ( mentioned in april-june on p5p ).
Regards
Mattia
[1] try searching perlcc.PL for Test::Builder...
Re: [RFC] Switch to make Test::Builder output even if $^C ( for B::C )
On Sun, Jan 13, 2002 at 07:39:52PM +0100, Mattia Barbon wrote:
> > perlcc seems to be dropping BEGIN blocks entirely, that's the problem.
>
> No, that's correct. Explanation: if I have a module Foo
>
> package Foo;
>
> $x = 1;
> print "AAA";
>
> sub a { $x }
>
> 1;
>
> and a main program foo.pl
>
> BEGIN { # think use Foo;, expanded for clarity
> require Foo;
> }
>
> print Foo::a();
>
> perl -MO=C foo.pl
> calls B::C::compile _after_ it ran the BEGIN blocks; this means that the
> optree in Foo that initializes $x, and does "print AAA" has already been
> freed. So, even if B::C could save BEGIN blocks, this is not a good
> idea, for quite a lot of reasons.
$ bleadperl -MO=-qq,Deparse foo.plx
sub BEGIN {
print "foo\n";
}
print "bar\n";
If B::Deparse can save BEGIN blocks, B::C can.
--
Michael G. Schwern <[EMAIL PROTECTED]>http://www.pobox.com/~schwern/
Perl Quality Assurance <[EMAIL PROTECTED]> Kwalitee Is Job One
I have this god-awful need to aquire useless crap!!!
Re: [RFC] Switch to make Test::Builder output even if $^C ( for B::C )
> On Sun, Jan 13, 2002 at 07:39:52PM +0100, Mattia Barbon wrote:
> > > perlcc seems to be dropping BEGIN blocks entirely, that's the problem.
> >
> > No, that's correct. Explanation: if I have a module Foo
> >
> > package Foo;
> >
> > $x = 1;
> > print "AAA";
> >
> > sub a { $x }
> >
> > 1;
> >
> > and a main program foo.pl
> >
> > BEGIN { # think use Foo;, expanded for clarity
> > require Foo;
> > }
> >
> > print Foo::a();
> >
> > perl -MO=C foo.pl
> > calls B::C::compile _after_ it ran the BEGIN blocks; this means that the
> > optree in Foo that initializes $x, and does "print AAA" has already been
> > freed. So, even if B::C could save BEGIN blocks, this is not a good
> > idea, for quite a lot of reasons.
I didn't write what I meant, sorry, see below
> $ bleadperl -MO=-qq,Deparse foo.plx
> sub BEGIN {
> print "foo\n";
> }
> print "bar\n";
>
> If B::Deparse can save BEGIN blocks, B::C can.
I didn't mean that I can't write code to make B::C save BEGIN blocks
( it'd require <10 lines, probably ), I did mean that doing so would
not be a god idea: _I am
saving the state of the program after those blocks were ran_ and
they will be run _another time_ at runtime, and this is not correct:
( for example use lib 'a'; would put 'a' into @INC twice, once
( correctly ) at compile time, and another time ( incorrectly ) at runtime ). In this
case this is not harmful, but you get the idea.
Regards
Mattia
Compiled programs to keep BEGIN blocks? (was Re: [RFC] Switch to make Test::Builder output even if $^C ( for B::C ))
On Sun, Jan 13, 2002 at 10:04:58PM +0100, Mattia Barbon wrote:
> > $ bleadperl -MO=-qq,Deparse foo.plx
> > sub BEGIN {
> > print "foo\n";
> > }
> > print "bar\n";
> >
> > If B::Deparse can save BEGIN blocks, B::C can.
>
> I didn't mean that I can't write code to make B::C save BEGIN blocks
> ( it'd require <10 lines, probably ), I did mean that doing so would
> not be a god idea: _I am
> saving the state of the program after those blocks were ran_ and
> they will be run _another time_ at runtime, and this is not correct:
> ( for example use lib 'a'; would put 'a' into @INC twice, once
> ( correctly ) at compile time, and another time ( incorrectly ) at
> runtime ). In this
> case this is not harmful, but you get the idea.
I don't understand. The compiled program should do exactly what the
original program did. Anything else, as difficult as it may be, is a
bug. Lots of programs and modules do important load-time checks and
logic inside BEGIN blocks.
Why would this:
BEGIN {
push @INC, 'foo';
}
put 'foo' into @INC twice if it were compiled? The compiled program
should not be storing the post-BEGIN value of @INC, it should store
the original value at startup.
--
Michael G. Schwern <[EMAIL PROTECTED]>http://www.pobox.com/~schwern/
Perl Quality Assurance <[EMAIL PROTECTED]> Kwalitee Is Job One
Me? A robot? That's rediculous! For one thing, that doesn't compute at all!
