if (SvROK(sv) && SvTYPE(sv) == SVt_PVCV)
   warn("sv is a code reference (CV) alright.");
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As for your second question, you can check that an sv is a reference to an object of (or derived from) a given class using sv_derived_from() (untested all the way):

if (SvROK(sv) && sv_derived_from(sv, "Foo"))
   warn("sv isa Foo");
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And to check that a method is valid for a given class you can do something like (really untested):

if (gv_fetchmethod(gv_stashpv("Foo", 0), "Foo::bar"))
   warn("succeeded in finding Foo::bar");
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Now, I doubt I answered your all your questions, but you weren't exactly clear about what you're trying to do. Maybe you can explain in more detail?

-sam

I think gv_fetchmethod() is sort of what I was looking for. In the situation I'm working with, perl passes to SV's to an XSUB. I verify (in one particular code branch) that the first is a reference to a blessed object, and that the second is a string. I would like to verify that the string is a valid method on the object before I call call_method(). The tricky bit is, I don't know the class name of the blessed object, I just have an instance reference. Is there some way to get the class name of the object?

I think you might be able to use HvNAME(SvSTASH(sv)) for that. Give it a try and see if that works.

-sam

I doubt if this is a complete answer, but the C linker does static checking of function names and signatures. If the dll, libfoo.so, doesn't have a foofunc() in its symbol table, the linker errs out when you try to build an xs interface which provides &LibFoo::foofunc.

After Compline,
Zaxo

What are you talking about? What does the C linker have to do with manipulating SVs inside an XSUB?

-sam