Re: Action at a distance (updated)

I'm not an expert on Math::BigInt, but it seems to create objects and by copying you are always accessing the same instance.

And when searching for a clone method I found this in the documentation

$y = $x->copy(); # make a copy (unlike $y = $x)

So maybe try this?

HTH! :)

update

> This behaviour can be avoided if I use the overloaded ++ operator instead of the binc() method call:

Well you could "overload" assignments via tie, to always do a copy ...

see overload#Overloadable Operations:

> Simple assignment is not overloadable (the = key is used for the "Copy Constructor"). Perl does have a way to make assignments to an object do whatever you want, but this involves using tie(), not overload - see "tie" in perlfunc and the "COOKBOOK" examples below.

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

Wikisyntax for the Monastery}

Comment on Re: Action at a distance (updated) Select or Download Code

Replies are listed 'Best First'.
Re^2: Action at a distance by syphilis (Archbishop) on Nov 03, 2022 at 12:42 UTC
well you could "overload" assignments via tie to always do a copy Yes - that might be what I'm after. I'm looking for a solution that would be applied inside Math::BigInt. I'll see if I can get my head around it. (Thanks for the link.) I actually struck the problem in Math::MPFR (which is where I'd like to fix it), but used Math::BigInt as the demo because everyone already has that module and I believe that it's the same issue with both of those modules. Cheers, Rob	[reply]
Re^2: Action at a distance (updated) by ikegami (Patriarch) on Nov 03, 2022 at 14:29 UTC
I wouldn't go with `tie` (if it even works?). I'd overload `=` to automatically clone the object on assignment. Another approach is to use immutable objects. Such a class wouldn't provide a method for incrementing the object; it would provide a method that returns a new object with the higher value. Both of these approaches add the unnecessary computational and memory overhead of creating clones in situations where they aren't needed.	[reply] [d/l] [select]
Re^3: Action at a distance by LanX (Saint) on Nov 03, 2022 at 15:05 UTC
> I'd overload = to automatically clone the object on assignment. Sorry, that's too easy to misunderstand. Let me be more precise: `$b = $a` with `=` overloaded to `->clone` will not do an immediate `$b = $a->clone` ° It's rather a kind of copy-on-write. After the assignment the refs will still be identical : `$b == $a` The `->clone` ("copy" in COW) will only happen delayed just prior to changing `$b` or `$a` ("write" in COW) see https://perldoc.perl.org/overload#Copy-Constructor `$a = $b; # ... (other code which does not modify $a or $b) ... ++$b;` [download] would be executed in a manner equivalent to `$a = $b; # ... $b = $b->clone(undef, ""); $b->incr(undef, "");` [download] But the wording is fuzzy and needs to be tested. Anyway this could indeed fix the problem of the OP in an efficient way. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery} °) In Math::BigInt the cloning is done with the method ->copy	[reply] [d/l] [select]
Re^2: Action at a distance (updated) by ikegami (Patriarch) on Nov 03, 2022 at 14:15 UTC
~~You can overload `=` to get the desired effect. But that only works if you have immutable objects.~~	[reply] [d/l]
Re^3: Action at a distance (updated) by LanX (Saint) on Nov 03, 2022 at 14:24 UTC
> You can overload = to get the desired effect. Not sure what you mean, the reason why I've put "overload" in double-quotes is that it's not possible to change° assignment via overload. One needs to tie the obj-ref too, see the linked doc. Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery} update °) well, not the immediate assignment, see Re^3: Action at a distance	[reply]
Re^4: Action at a distance (updated) by ikegami (Patriarch) on Nov 03, 2022 at 14:30 UTC
Sorry, I hadn't read the post script. I was replying to the `tie` bit.	[reply] [d/l]