Re: Close($file) required in Perl 6, unlike Perl 5
On 07/13/2011 10:00 PM, Parrot Raiser wrote: > The following program: > > my $skeleton = "bones\n"; > my $new_file = "grave"; > my $handle = open($new_file, :w); > $handle.print($skeleton); > > opens the "grave" file, but leaves it empty. A last line: > > close($handle);# "close()" generates an error message. > > is required to get any contents in the file, unlike the equivalent Perl 5 > code: That's because Rakudo isn't yet able to execute any code (like a DESTROY method in Perl 5) when the garbage collector detects that an object is not referenced anywhere anymore. So it's a limitation in Rakudo, not a change in the language. An intrinsic difference is that Perl 5 guarantees a timely execution of such methods (because it is reference counted), whereas Perl 6 does not. Question to the Parrot developers: How could I implement DESTROY methods in Rakudo? Is there any vtable I can override, or so? Note that such a method might itself allocate new GCables. While not urgent, it's important for us in the long run. Cheers, Moritz
Re: Bug?
On 07/14/2011 11:47 PM, Parrot Raiser wrote:
> When a subroutine is invoked with an empty parameter list, as follows:
>
> run_stuff();
>
> sub run_stuff {
> my ($parm) = @_;
> say "Parameter is $parm";
> }
>
> @_[0] contains "Any()".
Not "Any()", but Any (which say() prints as "Any()" to ease debugging)
> Should it?
Yes.
Re: Close($file) required in Perl 6, unlike Perl 5
On Sun, Jul 17, 2011 at 10:21:19AM +0200, Moritz Lenz wrote:
>
> Question to the Parrot developers: How could I implement DESTROY methods
> in Rakudo? Is there any vtable I can override, or so? Note that such a
> method might itself allocate new GCables. While not urgent, it's
> important for us in the long run.
A possibly related (and more relevant) question for Parrot devs:
is there any reason that FileHandle PMCs do not automatically
flush + close on destruction?
pmichaud@kiwi:~/nom$ cat fh.pir
.sub 'main' :main
$P0 = new ['FileHandle']
$P1 = $P0.'open'('test.txt', 'w')
$P1.'print'("Hello\n")
.end
pmichaud@kiwi:~/nom$ install/bin/parrot fh.pir
pmichaud@kiwi:~/nom$ cat test.txt
pmichaud@kiwi:~/nom$ ls -l test.txt
-rw-r--r-- 1 pmichaud pmichaud 0 2011-07-17 09:57 test.txt
Pm
Re: Bug?
On Sun, Jul 17, 2011 at 10:40:01AM +0200, Moritz Lenz wrote:
> On 07/14/2011 11:47 PM, Parrot Raiser wrote:
> > When a subroutine is invoked with an empty parameter list, as follows:
> >
> > run_stuff();
> >
> > sub run_stuff {
> > my ($parm) = @_;
> > say "Parameter is $parm";
> > }
> >
> > @_[0] contains "Any()".
>
> Not "Any()", but Any (which say() prints as "Any()" to ease debugging)
>
> > Should it?
>
> Yes.
Not exactly -- master gets this wrong. Type objects are supposed
to stringify to "" and produce a warning.
Nom (cf0da7d) also gets this somewhat wrong at present (but still better
than master); it's treating the assignment as an item assignment.
Pm
Re: Bug?
On Jul 14, 2011, at 4:47 PM, Parrot Raiser wrote:
When a subroutine is invoked with an empty parameter list, as follows:
run_stuff();
sub run_stuff {
my ($parm) = @_;
say "Parameter is $parm";
}
@_[0] contains "Any()".
Should it?
Yes, but only because of the way you are inspecting it.
When run_stuff is called with no arguments, @_ is empty.
It does *not* contain an element with the value Any; it contains no
elements at all.
When you ask for the value of a specific (and non-existent) element of
the array,
you only see that the element has no defined value yet.
(The `Any` value in Perl 6 is like the `undef` value in Perl 5.)
The same will happen if you declared @foo, then asked for the value of
@foo[42].
perl -MData::Dumper -e 'sub look { print Dumper scalar(@_), \@_,
$_[0]; } look();'
$VAR1 = 0;
$VAR2 = [];
$VAR3 = undef;
perl6 -e 'sub look { .say for @_.elems, @_.perl, @_[0].perl; }; look();'
0
[]
Any
--
Hope this helps,
Bruce Gray (Util)
