Can they be rewritten? Yes. It's just code.

Replacing XS is a big deal though. That's a bigger break than syntax, because 30% of the CPAN won't work with new releases.

Nicholas Clark's Ponie work shows one way where it's difficult. Artur Bergman ran an experiment around the same time to migrate SVs to something more like Parrot's PMCs, where every data type had virtual methods in well-defined slots instead of accessor macros. That didn't go very far either. These are fundamental assumptions of perl's implementation without any encapsulation beyond C macros.

It'll be a lot of work.

The best way I've ever figured out to do this is to introduce an abstraction layer for XS that's not XS and that lets the core gradually migrate away from the XS-ish implementation, but even that's a decades-long project I fear.

> PMCs, where every data type had virtual methods in well-defined slots instead of accessor macros

Well my first idea was, why not write a wrapper macro/class which applies the accessor macros in form of "virtual methods in well-defined slots"?

> The best way I've ever figured out to do this is to introduce an abstraction layer for XS that's not XS

Are you going into the same direction here?

Why would we need to gradually migrate away from XS then?

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

UPDATE s/CS/XS/ typo

Well my first idea was, why not write a wrapper macro/class which applies the accessor macros in form of "virtual methods in well-defined slots"?

It's been a long time since I thought about such a thing, but I don't know how much work it would be to write lvalue macros that could call set_ methods appropriately.

Why would we need to gradually migrate away from XS then?

CPAN/DarkPAN authors who want to support multiple language versions with a single release.