piggy back infos on a string scalar

LanX has asked for the wisdom of the Perl Monks concerning the following question:

I have to tunnel extra information (about creation) to a string passed to a third party module.

The module expects a string and I have an API to later retrieve that string.

Two approaches come to mind:

Tie::Scalar the string to act like a normal string, but later use tied to retrieve the underlying object with the infos
pass an $obj with an overload to stringify to the desired string but encapsulate further info inside the object

Before reinventing the wheel, are there already older (or other) solutions for that?

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

Wikisyntax for the Monastery}

Comment on piggy back infos on a string scalar

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Re: piggy back infos on a string scalar by haj (Vicar) on Feb 23, 2023 at 18:26 UTC
String::Tagged allows to attach data to (arbitrary parts of a) string, the objects "behave like strings". This is a bit of over-engineering if you need to attach only to the string as a whole, but alas, it's already existing!	[reply]
Re^2: piggy back infos on a string scalar by LanX (Saint) on Feb 23, 2023 at 18:56 UTC
Thanks, very interesting, I'm working on something roughly similar... Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply]
Re: piggy back infos on a string scalar by kikuchiyo (Hermit) on Feb 23, 2023 at 22:35 UTC
There is perhaps Variable::Magic? It even has an example "useful for passing user data through limited APIs". Caveat: "Magic is not copied on assignment." So whether this technique works for you depends on what your third party module does with the string.	[reply]
Re^2: piggy back infos on a string scalar by LanX (Saint) on Feb 23, 2023 at 22:57 UTC
Thanks, I already tested the overload approach and it works fine ... at least for the time being. The third party module is DBI and it's the statement string with attached debug infos. When inspecting `$sth->{Statement}` I can see the original object while `$sth = $dbh->prepare($stmt_obj)` processed the stringification. (Alas it's a bit more complicated since DBI depends on driver implementations which may differ, I already stumbled over things which are different for MySQL than documented, so testing and adjusting might be needed.) Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re: piggy back infos on a string scalar by tobyink (Canon) on Feb 24, 2023 at 16:04 UTC
Use object overloading. Ties and Variable::Magic (which was mentioned elsewhere in the thread) attach to the variable, not to the value, like this: my $x = "Hello world"; attach_some_special_magic( $x ); my $y = $x; # $y has no special magic As you're passing the string around, you don't want that. You want an overloaded object. The danger with overloaded objects is that the third-party module you mention might check `!ref( $str )` to ensure it's been passed a string. If it's doing that, you still have one workaround. Bless the object into a package called "0". Then `ref( $str )` will return "0" which is false. Hire me at Toby Ink Ltd or Join my OnlyFans	[reply] [d/l] [select]
Re^2: piggy back infos on a string scalar by LanX (Saint) on Feb 24, 2023 at 16:30 UTC
> Bless the object into a package called "0". Then `ref( $str )` will return "0" which is false. LOL. I think the `"0"` namespace could become quite overloaded now ;-) Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l] [select]
Re^3: piggy back infos on a string scalar by tobyink (Canon) on Feb 24, 2023 at 21:37 UTC
Well yeah, certainly don't use the "0" namespace for anything you want to be re-usable. Same as how you wouldn't use "main". Hire me at Toby Ink Ltd or Join my OnlyFans	[reply]
Re^4: piggy back infos on a string scalar by LanX (Saint) on Feb 24, 2023 at 23:17 UTC