SV Manipulation Functions

Returns a boolean indicating whether the SV is derived from the specified class at the C level. To check derivation at the Perl level, call isa() as a normal Perl method.

Returns a boolean indicating whether the SV performs a specific, named role. The SV can be a Perl object or the name of a Perl class.

A specialised variant of croak() for emitting the usage message for xsubs

croak_xs_usage(cv, "eee_yow");

works out the package name and subroutine name from cv, and then calls croak(). Hence if cv is &ouch::awk, it would call croak as:

Perl_croak(aTHX_ "Usage %s::%s(%s)", "ouch" "awk", "eee_yow");