Index: generic/predefined.h
===================================================================
diff -u -r3b2edfa776291682e0d251322997aad328b885df -rdd7a26337aa9aec3e0a06d2137ee7e708a8e1a9a
--- generic/predefined.h	(.../predefined.h)	(revision 3b2edfa776291682e0d251322997aad328b885df)
+++ generic/predefined.h	(.../predefined.h)	(revision dd7a26337aa9aec3e0a06d2137ee7e708a8e1a9a)
@@ -15,15 +15,11 @@
 "eval [linsert $cmd 1 $object]} else {\n"
 "eval [linsert $(definition) 1 $object]}} else {\n"
 "error \"cannot require method $name for $object, method unknown\"}}\n"
-"set ::nsf::parametersyntax(::nsf::mixin) \"object ?-per-object? classes\"\n"
-"proc ::nsf::mixin {object args} {\n"
-"if {[lindex $args 0] eq \"-per-object\"} {\n"
-"set rel \"object-mixin\"\n"
-"set args [lrange $args 1 end]} else {\n"
-"set rel \"class-mixin\"}\n"
-"if {[lindex $args 0] ne \"\"} {\n"
+"::nsf::proc ::nsf::mixin {object -per-object:switch classes} {\n"
+"set rel [expr {${per-object} ? \"object-mixin\" : \"class-mixin\"}]\n"
+"if {[lindex $classes 0] ne \"\"} {\n"
 "set oldSetting [::nsf::relation $object $rel]\n"
-"uplevel [list ::nsf::relation $object $rel [linsert $oldSetting 0 $args]]} else {\n"
+"uplevel [list ::nsf::relation $object $rel [linsert $oldSetting 0 $classes]]} else {\n"
 "uplevel [list ::nsf::relation $object $rel \"\"]}}\n"
 "::nsf::provide_method autoname {::nsf::alias autoname ::nsf::methods::object::autoname}\n"
 "::nsf::provide_method exists   {::nsf::alias  exists ::nsf::methods::object::exists}\n"