Function exists

inst/include/Rcpp/Environment.h:163–172

* Indicates if an object called name exists in the * environment * * @param name name of the object * * @return true if the object exists in the environment */

         * @return true if the object exists in the environment
         */
        bool exists( const std::string& name ) const {
            SEXP nameSym = Rf_install(name.c_str());
#if R_VERSION < R_Version(4,5,0)
            SEXP res = Rf_findVarInFrame( Storage::get__() , nameSym  ) ;
            return res != R_UnboundValue;
#else
            SEXP res = R_getVarEx(nameSym, Storage::get__(), FALSE, NULL);
            return res != NULL;
#endif
        }

        /**
         * Attempts to assign x to name in this environment