"TB" == Tim Bunce [EMAIL PROTECTED] writes:
TB On Thu, Feb 15, 2001 at 02:26:10PM -0500, Uri Guttman wrote:
"TB" == Tim Bunce [EMAIL PROTECTED] writes:
TB As a part of that the weak reference concept, bolted recently into
TB perl5, could be made more central in perl6.
TB
Damien Neil wrote:
Using object lifetime to control state is almost never a good idea,
even if you have deterministic finalization. A much better approach
is to have methods which allow holders of the object to control it,
and a finalizer (DESTROY method) which cleans up only if necessary.
Hong Zhang
A deterministic finalization means we shouldn't need to force
programmers
to have good ideas. Make it easy, remember? :)
I don't believe such an algorithm exists, unless you stick with reference
count.
Either doesn't exist, or is more expensive than refcounting. I guess we
On Thu, Feb 15, 2001 at 08:21:03AM -0300, Branden wrote:
Hong Zhang
A deterministic finalization means we shouldn't need to force
programmers
to have good ideas. Make it easy, remember? :)
I don't believe such an algorithm exists, unless you stick with reference
count.
Either
Tim Bunce wrote:
On Thu, Feb 15, 2001 at 08:21:03AM -0300, Branden wrote:
And don't forget that if we stick with refcounting, we should try to
find a
way to break circular references, too.
As a part of that the weak reference concept, bolted recently into perl5,
could be made more central
On Thu, Feb 15, 2001 at 08:07:39AM -0300, Branden wrote:
I think you just said all about why we shouldn't bother giving objects
deterministic finalization, and I agree with you. If we explicitly want to
free resources (files, database connections), then we explicitly call close.
Otherwise, it
Damien Neil wrote:
On Thu, Feb 15, 2001 at 08:07:39AM -0300, Branden wrote:
I think you just said all about why we shouldn't bother giving objects
deterministic finalization, and I agree with you. If we explicitly want
to
free resources (files, database connections), then we explicitly
Branden wrote:
Just set autoflush, if you're lazy...
And say goodbye to performance...
The problem is
that you can not only count on $fh's DESTROY being called at the end of
the block, you often can't count on it ever happening.
Anyway, the file would be flushed and closed...
That's
Hong Zhang wrote:
This code should NEVER work, period. People will just ask for trouble
with this kind of code.
Actually I meant to have specified "" as the mode, i.e. append, then
what I originally said holds true. This behaviour is predictable and
dependable in the current perl
Hong Zhang wrote:
This code should NEVER work, period. People will just ask for trouble
with this kind of code.
Actually I meant to have specified "" as the mode, i.e. append, then
what I originally said holds true. This behaviour is predictable and
dependable in the current perl
Hong Zhang wrote:
That was not what I meant. Your code already assume the existence of
reference counting. It does not work well with any other kind of garbage
collection. If you translate the same code into C without putting in
the close(), the code will not work at all.
Wrong, it does
Alan Burlison wrote:
I think you'll find that both GC *and* reference counting scheme will
require the heay use of mutexes in a MT program.
There are several concurrent GC algorithms that don't use
mutexes -- but they usually depend on read or write barriers
which may be really hard for us to
There are several concurrent GC algorithms that don't use
mutexes -- but they usually depend on read or write barriers
which may be really hard for us to implement. Making them run
well always requires help from the OS memory manager and that
would hurt portability. (If we don't have OS
Hong Zhang wrote:
The memory barriers are always needed on SMP, whatever algorithm
we are using.
I was just pointing out that barriers are an alternative to mutexes.
Ref count certainly would use mutexes instead of barriers.
The memory barrier can be easily coded in assembly, or intrinsic
At 02:08 PM 2/15/2001 -0800, Hong Zhang wrote:
Hong Zhang wrote:
This code should NEVER work, period. People will just ask for trouble
with this kind of code.
Actually I meant to have specified "" as the mode, i.e. append, then
what I originally said holds true. This behaviour is
At 09:13 PM 2/15/2001 -0500, Ken Fox wrote:
Hong Zhang wrote:
The memory barriers are always needed on SMP, whatever algorithm
we are using.
I was just pointing out that barriers are an alternative to mutexes.
Ref count certainly would use mutexes instead of barriers.
Not really they
At 07:44 PM 2/14/2001 +, Simon Cozens wrote:
On Wed, Feb 14, 2001 at 08:32:41PM +0100, [EMAIL PROTECTED] wrote:
DESTROY would get called twice, which is VERY BAD.
*blink*
It is? Why?
I grant you it isn't the clearest way of programming, but "VERY BAD"?
package
On Wed, Feb 14, 2001 at 02:10:59PM -0300, Branden wrote:
Dan Sugalski wrote:
Plus there's nothing stopping you from having $obj-DESTROY in your own
code, though it may be inadvisable.
It is (mainly) inadvisable because:
1. GC will call DESTROY when it collects the memory, so DESTROY
On Wed, Feb 14, 2001 at 08:32:41PM +0100, [EMAIL PROTECTED] wrote:
DESTROY would get called twice, which is VERY BAD.
*blink*
It is? Why?
I grant you it isn't the clearest way of programming, but "VERY BAD"?
package NuclearReactor::CoolingRod;
sub new {
[[ reply goes to -internals ]]
OK. Let's clear it up all at once from start. Below is the lifecycle of an
object (in Perl). A reference is blessed, and an object is the result of
this blessing. During the object's life, several methods of it are called,
but independent of which are called, it
[trimming distribution to -internals only]
On Wed, Feb 14, 2001 at 07:44:53PM +, Simon Cozens wrote:
package NuclearReactor::CoolingRod;
sub new {
Reactor-decrease_core_temperature();
bless {}, shift
}
sub DESTROY {
Reactor-increase_core_temperature();
}
A better
On Wed, Feb 14, 2001 at 01:24:34PM -0800, Damien Neil wrote:
Using object lifetime to control state is almost never a good idea,
even if you have deterministic finalization.
A deterministic finalization means we shouldn't need to force programmers
to have good ideas. Make it easy, remember?
On Thu, Feb 15, 2001 at 12:11:27AM +, Simon Cozens wrote:
Using object lifetime to control state is almost never a good idea,
even if you have deterministic finalization.
A deterministic finalization means we shouldn't need to force programmers
to have good ideas. Make it easy,
[moved to -internals]
On Mon, 12 Feb 2001 01:44:54 -0500, Dan Sugalski [EMAIL PROTECTED] wrote:
Perl needs some level of tracking for objects with finalization attached to
them. Full refcounting isn't required, however. Also, the vast majority of
perl variables have no finalization attached
Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
Also, the vast majority of perl variables have no finalization
attached to them.
That's true, but without static typing don't you have to treat them as if
they did? At the very least you need to do a "is it an object with a
Jan Dubois wrote:
On Mon, 12 Feb 2001 01:44:54 -0500, Dan Sugalski [EMAIL PROTECTED] wrote:
Perl needs some level of tracking for objects with finalization attached
to
them. Full refcounting isn't required, however. Also, the vast majority
of
perl variables have no finalization attached to
At 01:45 PM 02-12-2001 -0300, Branden wrote:
I think having both copying-GC and refcounting-GC is a good idea. I may be
saying a stupid thing, since I'm not a GC expert, but I think objects that
rely on having their destructors called the soonest possible for resource
cleanup could use a
Buddha Buck wrote:
At 01:45 PM 02-12-2001 -0300, Branden wrote:
Am I too wrong here?
It's... complicated...
Agreed.
Here's an example of where things could go wrong:
sub foo {
my $destroyme1 = new SomeClass;
my $destroyme2 = new SomeClass;
my @processme1;
At 10:38 AM 2/12/2001 -0500, Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
Perl needs some level of tracking for objects with finalization attached to
them. Full refcounting isn't required, however.
I think I've heard you state that before. Can you be more specific? What
At 11:01 PM 2/11/2001 -0800, Jan Dubois wrote:
[moved to -internals]
On Mon, 12 Feb 2001 01:44:54 -0500, Dan Sugalski [EMAIL PROTECTED] wrote:
Perl needs some level of tracking for objects with finalization attached to
them. Full refcounting isn't required, however. Also, the vast majority of
At 09:49 AM 2/12/2001 -0800, Jan Dubois wrote:
On Mon, 12 Feb 2001 14:50:44 -0300, "Branden" [EMAIL PROTECTED]
wrote:
Actually I was thinking something like PMCs ($@%) being copy-GCed and
referred objects (new SomeClass) being refcounted. In this case above, every
operation would use
On Mon, 12 Feb 2001 14:50:44 -0300, "Branden" [EMAIL PROTECTED]
wrote:
Actually I was thinking something like PMCs ($@%) being copy-GCed and
referred objects (new SomeClass) being refcounted. In this case above, every
operation would use refcount's, since they're storing objects in PMCs. What
On Mon, 12 Feb 2001 13:33:52 -0500 (EST), Sam Tregar [EMAIL PROTECTED]
wrote:
It's reasonably obvious (which is to say "cheap") which variables aren't
involved with anything finalizable.
Probably a simple bit check and branch. Is that cheap? I guess it must
be.
Yes, but incrementing the
On Mon, 12 Feb 2001, Dan Sugalski wrote:
I think I've heard you state that before. Can you be more specific? What
alternate system do you have in mind? Is this just wishful thinking?
This isn't just wishful thinking, no.
You picked the easy one. Maybe you can get back to the other two
On Mon, 12 Feb 2001 13:29:21 -0500, Dan Sugalski [EMAIL PROTECTED] wrote:
At 10:38 AM 2/12/2001 -0500, Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
Perl needs some level of tracking for objects with finalization attached to
them. Full refcounting isn't required, however.
I
On Mon, Feb 12, 2001 at 01:33:52PM -0500, Sam Tregar wrote:
Perhaps. It's not rare in OO Perl which is coincidentally one area in
serious need of a speedup. I suppose I'm warped by my own experience -
all the code I see every day is filled with references and objects.
That's probably not
At 01:33 PM 2/12/2001 -0500, Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
I think I've heard you state that before. Can you be more specific? What
alternate system do you have in mind? Is this just wishful thinking?
This isn't just wishful thinking, no.
You picked the
At 10:46 AM 2/12/2001 -0800, Jan Dubois wrote:
On Mon, 12 Feb 2001 13:29:21 -0500, Dan Sugalski [EMAIL PROTECTED] wrote:
At 10:38 AM 2/12/2001 -0500, Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
Perl needs some level of tracking for objects with finalization
attached to
Dan Sugalski [EMAIL PROTECTED] writes:
At 10:38 AM 2/12/2001 -0500, Sam Tregar wrote:
On Mon, 12 Feb 2001, Dan Sugalski wrote:
Perl needs some level of tracking for objects with finalization attached to
them. Full refcounting isn't required, however.
I think I've heard you state
On Mon, Feb 12, 2001 at 05:33:05PM -0500, Dan Sugalski wrote:
package foo;
use attrs qw(cleanup_sub);
would be nice, but I don't know that he'll go for it. (Though it's the only
way I can think of to avoid AUTOLOAD being considered a potential destructor)
Fiat?
It's pretty hard (for
At 11:28 PM 2/12/2001 +0100, Robin Berjon wrote:
At 15:37 12/02/2001 -0500, Dan Sugalski wrote:
It *is* rare in OO perl, though. How many of the variables you use are
really, truly in need of finalization? .1 percent? .01 percent? Less? Don't
forget that you need to count every scalar in every
On Sunday 11 February 2001 19:08, Jan Dubois wrote:
However, I couldn't solve the problem of "deterministic destruction
behavior": Currently Perl will call DESTROY on any object as soon as the
last reference to it goes out of scope. This becomes important if the
object own scarce external
On Sun, 11 Feb 2001 21:11:09 -0500, "Bryan C. Warnock"
[EMAIL PROTECTED] wrote:
On Sunday 11 February 2001 19:08, Jan Dubois wrote:
However, I couldn't solve the problem of "deterministic destruction
behavior": Currently Perl will call DESTROY on any object as soon as the
last reference to it
On Sun, 11 Feb 2001, Jan Dubois wrote:
However, I couldn't solve the problem of "deterministic destruction
behavior": Currently Perl will call DESTROY on any object as soon as the
last reference to it goes out of scope. This becomes important if the
object own scarce external resources
At 11:36 PM 2/11/2001 -0500, Sam Tregar wrote:
On Sun, 11 Feb 2001, Jan Dubois wrote:
However, I couldn't solve the problem of "deterministic destruction
behavior": Currently Perl will call DESTROY on any object as soon as the
last reference to it goes out of scope. This becomes important
Dan Sugalski wrote:
At 12:06 PM 2/9/2001 -0500, Ken Fox wrote:
2. Work proportional to live data, not total data. This is hard to
believe for a C programmer, but good garbage collectors don't have
to "free" every allocation -- they just have to preserve the live,
or
On Fri, Feb 09, 2001 at 01:19:36PM -0500, Dan Sugalski wrote:
The less memory you chew through the faster your code will probably be (or
at least you'll have less overhead). Reuse is generally faster and less
resource-intensive than recycling. What's true for tin cans is true for memory.
At 06:30 PM 2/9/2001 +, Nicholas Clark wrote:
On Fri, Feb 09, 2001 at 01:19:36PM -0500, Dan Sugalski wrote:
The less memory you chew through the faster your code will probably be (or
at least you'll have less overhead). Reuse is generally faster and less
resource-intensive than
At 04:53 PM 2/9/2001 -0500, Ken Fox wrote:
Dan Sugalski wrote:
At 04:09 PM 2/9/2001 -0200, Branden wrote:
If I change the way some objects are used so
that I tend to create other objects instead of reusing the old ones, I'm
actually not degrading GC performance, since its work is
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