Hi, current git, the code below. In general: we look if given argument exists in a bundle and if so we check its typeof(). The first end the second examples work fine, but at the third evaluation of 'model_prior' looks like ommited we get error: "internal genr error: aux node mismatch". Marcin <hansl> set verbose off function void FOO (bundle UserOpts) bundle Overloadable string arg_name, type_of strings OverloadableKeys Overloadable["bic_type"] = _(bic=1, hbic=2, ibic=3) Overloadable["model_prior"] = _(binomial=1, betabinomial=2) Overloadable["with_const"] = _(never=0, always=1, canbedropped=2) OverloadableKeys = getkeys(Overloadable) eval OverloadableKeys loop i=1..nelem(OverloadableKeys) --quiet arg_name = OverloadableKeys[i] if inbundle(UserOpts, arg_name) if typeof(UserOpts[arg_name]) == 4 type_of = "string" else type_of = "non-string" endif printf "Typeof %s is %s\n", arg_name, type_of endif endloop end function printf "The first examle:\n" FOO(_(bic_type="bic", with_const=0)) printf "\nThe second examle:\n" FOO(_(bic_type="bic", model_prior="binomial", with_const="always")) printf "\nThe third examle:\n" FOO(_(bic_type="bic", model_prior="binomial", with_const=0)) </hansl>