Re^3: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object?

A unique textual identifier for each object. A name following rules and closely coupled to an object.

To get the actual reference, you'll call a class method like My::File->get_obj(symbol) to lookup in %My::File::instance

That's the "weakest" way...

Update

This allows to designs systems where warnings like "object (File/Directory) doesn't exist anymore" are possible. Think inodes!

Also keep in mind that Perl can reuse refs for new variables after destructions, tho I doubt this happens when there is still a weakened ref around. (?)

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

see Wikisyntax for the Monastery}

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Re^4: Should I use weaken on an object attribute containing a reference to an object which contains reference back to original object? by hv (Prior) on Jan 21, 2024 at 18:33 UTC
Also keep in mind that Perl can reuse refs after destructions, tho I doubt this happens when there is still a weakened ref around. (?) If all the strong refs to an object go away, it gets freed; there is nothing stopping the memory being reused after that. When a reference is weakened, a flag is set on the reference, and a record of the reference is added to a list of weakrefs attached to the object (stored under `PERL_MAGIC_backref` magic). When the object gets freed, it uses that list to set the affected weakrefs to undef to keep things safe. Note that the weakrefs are stored as a simple list, so freeing a weakref can get expensive when an individual object has many weakrefs to it: it has to do an O(n) scan of the list to find the entry to remove, so removing all of the weakrefs individually is O(n^2) whereas removing them in one go by freeing the object is O(n).	[reply] [d/l]
Re^5: 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 19:37 UTC
Thanks, that sounds like the good design I expected. 👍🏼 Apart from the note about the complexity of long lists, but yeah having tons of weak refs is hopefully only a rare edge case. :) Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery} update See also perlref#Circular-References	[reply]

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