Adopting one from Zefram Back in 2011, Andrew Main, known to the Perl community as Zefram, released Devel::CallParser . It was a quiet piece of infrastructure: a C API that let XS modules attach custom argument parsers to Perl subroutines. Where the core's PL_keyword_plugin API was awkward to work with directly, CallParser gave you a structured way to extend Perl's syntax from C. Zefram maintained it through 2013, fixing compatibility issues with indirect and Sub::StrictDecl , working around padrange optimiser changes, and shipping version 0.002. Then silence. The module sat on CPAN, unmaintained, while Perl kept moving. By the current year and perl version it was breaking. I personally could not install it locally on my hardened macOS runtimes, many reports of issues on threaded builds, shifted qerror internals, and many red reports on CPAN testers.…