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Postings from December 2004
MJD wrote:
> That is talking about something else that is irrelevant in this case.
> That paragraph refers to this situation;
>
> { my $obj = Class->new;
> ...
> }
>
> B;
>
> The question here is whether Class::DESTROY is called immediately at
> the end of the block, before B is executed. The paragraph you quote
> is warning us that that might not be the case.
Well I read that as a general observation that you cant count on DESTROY
being called at any particular time, which to me implys order.
> However, the problem I am reporting is a different situation. Here, a
> piece of data is destroyed prematurely, while there is still a
> reference to it. That is not the same thing at all; Perl *does*
> guarantee that it will not destroy an object that is reachable from an
> executing program.
Only in normal destruction. It _cant_ make the guarantee that you say it
does or circular structures would never be broken during global destruction:
my $x=bless {},'Foo';
my $y=bless {},'Foo';
$x->{y}=$y;
$y->{x}=$x;
my $z;
$z=bless \$z,"Foo";
sub Foo::Destroy { print "Destroying: @_\n" }
> > Im wondering why Perl doesn't have a counter whose value is incremented
and
> > assigned to each blessed object when they are blessed.
>
> It maintains a count of the number of references to each object; this
> count is intended to prevent exactly the behavior I am reporting.
Not in global destruction though. Refcounting can't help there at all.
That's why I was suggesting the counter approach. At least then you could
know that the objects would be destroyed in a defined order.
yves
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