Creating closure callback from XS

XSTesting.xs

/*
 * Usage:
 
 my $x = XSTesting::makecb("my arg for x");
 my $y = XSTesting::makecb("my arg for y");
 say $x->();
 say $y->();

*/

#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#include "ppport.h"

XS(cb_test) {
	dVAR;
	dXSARGS;
	dORIGMARK;
	
	SV *var = (SV *) CvXSUBANY(cv).any_ptr;

	ST(0) = var;
	XSRETURN(1);
}

MODULE = XSTesting		PACKAGE = XSTesting

void makecb(SV *var)
	PPCODE:
		CV *myxs = newXS(0, cb_test, __FILE__);

		CvXSUBANY(myxs).any_ptr = (void *) var;

		ST(0) = sv_2mortal( newRV_noinc( (SV *) myxs ) );

		XSRETURN(1);