For instance how does the XS interface hinder the implementation of proper signatures?

Thanks, but I don't know how these things apply to subroutine signatures. For instance how does the XS interface hinder the implementation of proper signatures?

Well, I was talking in general terms about why perl5 doesn't tend to get new features, in response to your general compliant about the management of perl5.

But specifically for signatures, there are many things that can break in XS. For example, if we introduce new op types to handle signature processing, then XS modules which manipulate the optree, or which assume certain ops at the start of a sub, or which modify op behaviour by changing their pp_addr function pointer, may all break. Or modules which use keyword plugins and make certain assumptions about allowed syntax. Or XS code which directly manipulates @_. Or code which attempts to hook into subroutine entry and exit. Or profilers that think they know all valid op types.

There are many things that can break just that I can think of; when deployed, there will be other things that break that hadn't even occurred to me.

Dave.

These examples sound like XS code exploiting undocumented or internal features, without being widely used.

Manipulating the OP Tree? Does really anyone seriously use B::Generate ?

I'd be interested to see official API which would break with signatures

I can't see how 3rd party modules like Function::Parameters break XS code while implementing most of Perl6 semantics.*

It's a matter of management to introduce an experimental feature and give module maintainers exploiting undocumented stuff a time span to fix their code (or not).

The benefits of decent signatures outweighs any possible damage.

And not all modules are as important as JSON::XS and not all maintainers are reluctant to improvement like Schmorp is.

I hope you see my point.

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

*) and it might be worth checking if cperl's implementation of signatures broke any official XS API.