Re: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object?

if I delete the Dir, the Files can no longer reference the Dir

It's not only a question of deletion. The reference to Dir within File will disappear as soon as the Dir object gets out of scope, which is a Bad Thing™

use strict;
use warnings;
use Data::Dump;

my $file = Practice::File->new('foo');
{
    my $dir = Practice::Dir->new('bar');
    $file->add_dir($dir);
}
dd $file;

__DATA__
bless({ dir => undef, name => "foo" }, "Practice::File")
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Greetings,
-jo

$gryYup$d0ylprbpriprrYpkJl2xyl~rzg??P~5lp2hyl0p$

Comment on Re: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object? Download Code

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Re^2: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object? by LanX (Saint) on Jan 21, 2024 at 23:06 UTC
That's one of the reasons why I wrote that it depends on design decisions For instance, a common concept in filesystems is that deleting a directory is only possible if it's empty. => `rmdir` Another that deleting a directory also deletes the containing files. => `rm -r` In both cases all "File" objects having weak references to the "Dir" should have been removed. If that's done automatically in a `File:: DESTROY` method or only allowed to happen after a `$dir->rm` call are other design decisions. The problem here is that the OP's question is to vague to be answered. If this is all hypothetical and intended for `Practice::` instead for a real simulation of a file system, I'd say the topic is too ambiguous to discuss `weaken` Especially as I can't even tell that I know all subtle differences between different file systems. Hence there is no "natural" model to copy. Update At least, I don't know what a "directory getting deleted after going out of scope" would translate to in "normal practice" ...(?) Personally I wouldn't allow it to happen. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l] [select]

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Re^2: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object?
by LanX (Saint) on Jan 21, 2024 at 23:06 UTC

design decisions

For instance, a common concept in filesystems is that deleting a directory is only possible if it's empty. => rmdir

Another that deleting a directory also deletes the containing files. => rm -r

In both cases all "File" objects having weak references to the "Dir" should have been removed.

If that's done automatically in a File:: DESTROY method or only allowed to happen after a $dir->rm call are other design decisions.

The problem here is that the OP's question is to vague to be answered.

If this is all hypothetical and intended for Practice:: instead for a real simulation of a file system, I'd say the topic is too ambiguous to discuss weaken

Especially as I can't even tell that I know all subtle differences between different file systems. Hence there is no "natural" model to copy.

Update

At least, I don't know what a "directory getting deleted after going out of scope" would translate to in "normal practice" ...(?)

Personally I wouldn't allow it to happen.

Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

[reply]
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