Calling Perl from Rust

[vickenty]

There are four functions to call into Perl in XS, of which only one is currently supported.

• I32 call_sv(SV* sv, I32 flags);
• I32 call_pv(char *subname, I32 flags);
• I32 call_method(char *methname, I32 flags);
• I32 call_argv(char *subname, I32 flags, char **argv);

What would be the best way to represent different combinations of flags? Some of them are mutually exclusive, others depend on other flags.

A further improvement can be a macro that hides different ways to call a sub, and handles argument passing, something like:

call!(ctx, sub_sv, a, b, c);
call!(ctx, "Foo::name", a, b, c);
call!(ctx, sv->"name", a, b, c);
call!(ctx, sv->method_sv, a, b, c);