Index: generic/nsf.c
===================================================================
diff -u -rf0bca18a085d7e071f54af9b4f0136b65ad1f8e6 -r0756410503b3b64d5b057afbdc3acb14278ef379
--- generic/nsf.c	(.../nsf.c)	(revision f0bca18a085d7e071f54af9b4f0136b65ad1f8e6)
+++ generic/nsf.c	(.../nsf.c)	(revision 0756410503b3b64d5b057afbdc3acb14278ef379)
@@ -16727,13 +16727,11 @@
   nonnull_assert(pPtr != NULL);
   nonnull_assert(clientData != NULL);
 
-  fprintf(stderr, "Nsf_ConvertToTclObjType: converterArg %p\n", (void*)pPtr->converterArg);
   if (unlikely(pPtr->converterArg != NULL)) {
     const Tcl_ObjType *tclObjType = pPtr->converterArg->internalRep.twoPtrValue.ptr1;
 
     if (tclObjType != NULL) {
       result = Tcl_ConvertToType(interp, objPtr, tclObjType);
-      fprintf(stderr, "Nsf_ConvertToTclObjType:type  %p -> %d\n", (void*)tclObjType, result);
 
       if (result != TCL_OK) {
         Tcl_ResetResult(interp);
@@ -16794,9 +16792,15 @@
   nonnull_assert(clientData != NULL);
 
   if (unlikely(pPtr->converterArg != NULL)) {
-    Tcl_Obj *objv[4];
-    /*fprintf(stderr, "ConvertToTclobj %s (must be %s)\n", ObjStr(objPtr), ObjStr(pPtr->converterArg));*/
+    /*
+     * Using "string is ..." as value checker.
+     */
+    Tcl_Obj *objv[4], *resultObj;
+    /* fprintf(stderr, "ConvertToTclobj %s (must be %s)\n", ObjStr(objPtr), ObjStr(pPtr->converterArg));*/
 
+    resultObj = Tcl_GetObjResult(interp);
+    Tcl_IncrRefCount(resultObj);
+
     objv[0] = NULL;
     objv[1] = pPtr->converterArg;
     objv[2] = NsfGlobalObjs[NSF_OPTION_STRICT];
@@ -16805,14 +16809,23 @@
     result = NsfCallCommand(interp, NSF_STRING_IS, 4, objv);
     if (likely(result == TCL_OK)) {
       int success;
+
       Tcl_GetIntFromObj(interp, Tcl_GetObjResult(interp), &success);
       if (success == 1) {
         *clientData = objPtr;
+        /*
+         * Restore the original result, which was clobbered by the "string is"
+         * command. Restoring is necessary in cases, where this function is
+         * used as result value function of a method.
+         */
+        Tcl_SetObjResult(interp, resultObj);
       } else {
         Tcl_ResetResult(interp);
         result = NsfObjErrType(interp, NULL, objPtr, ObjStr(pPtr->converterArg), (Nsf_Param *)pPtr);
       }
     }
+    Tcl_DecrRefCount(resultObj);
+
   } else {
     result = TCL_OK;
 
@@ -31939,14 +31952,17 @@
     }
   }
   paramPtr = paramWrapperPtr->paramPtr;
-  if (paramPtrPtr != NULL) *paramPtrPtr = paramPtr;
+  if (paramPtrPtr != NULL) {
+    *paramPtrPtr = paramPtr;
+  }
 
   if (isNamed) {
     paramPtr->flags &= ~NSF_ARG_UNNAMED;
   }
 
   RUNTIME_STATE(interp)->doClassConverterOmitUnknown = 1;
   outObjPtr = NULL;
+
   result = ArgumentCheck(interp, valueObj, paramPtr, doCheckArguments, &flags, &checkedData, &outObjPtr);
   RUNTIME_STATE(interp)->doClassConverterOmitUnknown = 0;
 
Index: tests/returns.test
===================================================================
diff -u -r8e2e356e9bcef39f43dfe3690b82d9586c7adc72 -r0756410503b3b64d5b057afbdc3acb14278ef379
--- tests/returns.test	(.../returns.test)	(revision 8e2e356e9bcef39f43dfe3690b82d9586c7adc72)
+++ tests/returns.test	(.../returns.test)	(revision 0756410503b3b64d5b057afbdc3acb14278ef379)
@@ -9,147 +9,147 @@
 
 #
 # The same tests are in this test suite, once with and once without
-# checking 
+# checking
 #
 # Make sure, checking is turned on
 #
 ::nsf::configure checkresult true
 
 nx::test configure -count 10000
-nx::test case int-returns { 
-    nx::Class create C {
-	# scripted method without paramdefs
-	:method bar-ok1 {a b} {return 1}
-	:method bar-ok2 {a b} {return $a}
-	# scripted method with paramdefs
-	:method bar-nok {a b:integer} {return a}
-	# alias to tcl-cmd (no param defs)
-	:alias incr -frame object ::incr
-	:alias lappend -frame object ::lappend
-	:create c1
-    }
+nx::test case int-returns {
+  nx::Class create C {
+    # scripted method without paramdefs
+    :method bar-ok1 {a b} {return 1}
+    :method bar-ok2 {a b} {return $a}
+    # scripted method with paramdefs
+    :method bar-nok {a b:integer} {return a}
+    # alias to tcl-cmd (no param defs)
+    :alias incr -frame object ::incr
+    :alias lappend -frame object ::lappend
+    :create c1
+  }
 
-    ::nsf::method::property C bar-ok1 returns integer
-    ::nsf::method::property C bar-ok2 returns integer
-    ::nsf::method::property C bar-nok returns integer
-    ::nsf::method::property C incr returns integer
-    ::nsf::method::property C lappend returns integer
+  ::nsf::method::property C bar-ok1 returns integer
+  ::nsf::method::property C bar-ok2 returns integer
+  ::nsf::method::property C bar-nok returns integer
+  ::nsf::method::property C incr returns integer
+  ::nsf::method::property C lappend returns integer
 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} {expected integer but got "a" as return value}
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} {expected integer but got "a" as return value}
 
-    ? {c1 incr x} 1
-    ? {c1 incr x} 10002
+  ? {c1 incr x} 1
+  ? {c1 incr x} 10002
 
-    ? {c1 lappend l e1} {expected integer but got "e1" as return value}
+  ? {c1 lappend l e1} {expected integer but got "e1" as return value}
 
-    # query the returns value
-    ? {::nsf::method::property C lappend returns} integer
+  # query the returns value
+  ? {::nsf::method::property C lappend returns} integer
 
-    # reset it to empty
-    ? {::nsf::method::property C lappend returns ""} ""
-    ? {::nsf::method::property C bar-ok1 returns ""} ""
-    ? {::nsf::method::property C bar-ok2 returns ""} ""
-    ? {::nsf::method::property C bar-nok returns ""} ""
+  # reset it to empty
+  ? {::nsf::method::property C lappend returns ""} ""
+  ? {::nsf::method::property C bar-ok1 returns ""} ""
+  ? {::nsf::method::property C bar-ok2 returns ""} ""
+  ? {::nsf::method::property C bar-nok returns ""} ""
 
-    # no checking 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} a
-    ? {c1 lappend l e2} "e1 e2"
+  # no checking
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} a
+  ? {c1 lappend l e2} "e1 e2"
 
-    # query returns "", if there is no returns checking
-    ? {::nsf::method::property C lappend returns} ""
-    ? {::nsf::method::property ::nx::Class method returns} ""
+  # query returns "", if there is no returns checking
+  ? {::nsf::method::property C lappend returns} ""
+  ? {::nsf::method::property ::nx::Class method returns} ""
 
 }
 
 nx::test configure -count 10
-nx::test case app-specific-returns { 
+nx::test case app-specific-returns {
 
-    ::nx::methodParameterSlot object method type=range {name value arg} {
-        lassign [split $arg -] min max
-	if {$value < $min || $value > $max} {
-	    error "Value '$value' of parameter $name not between $min and $max"
-	}
-	return $value
+  ::nx::methodParameterSlot object method type=range {name value arg} {
+    lassign [split $arg -] min max
+    if {$value < $min || $value > $max} {
+      error "Value '$value' of parameter $name not between $min and $max"
     }
+    return $value
+  }
 
-    nx::Class create C {
-	:method bar-ok1 {a b} {return 1}
-	:method bar-ok2 {a b} {return $a}
-	:method bar-nok {a b:integer} {return a}
-	:alias incr -frame object ::incr
-	:alias lappend -frame object ::lappend
-	:create c1
-    }
+  nx::Class create C {
+    :method bar-ok1 {a b} {return 1}
+    :method bar-ok2 {a b} {return $a}
+    :method bar-nok {a b:integer} {return a}
+    :alias incr -frame object ::incr
+    :alias lappend -frame object ::lappend
+    :create c1
+  }
 
-    ::nsf::method::property C bar-ok1 returns range,arg=1-3
-    ::nsf::method::property C bar-ok2 returns range,arg=1-3
-    ::nsf::method::property C bar-nok returns range,arg=1-3
-    ::nsf::method::property C incr returns range,arg=1-30
-    ::nsf::method::property C lappend returns range,arg=1-30
+  ::nsf::method::property C bar-ok1 returns range,arg=1-3
+  ::nsf::method::property C bar-ok2 returns range,arg=1-3
+  ::nsf::method::property C bar-nok returns range,arg=1-3
+  ::nsf::method::property C incr returns range,arg=1-30
+  ::nsf::method::property C lappend returns range,arg=1-30
 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} {Value 'a' of parameter return-value not between 1 and 3}
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} {Value 'a' of parameter return-value not between 1 and 3}
 
-    ? {c1 incr x} 1
-    ? {c1 incr x} 12
+  ? {c1 incr x} 1
+  ? {c1 incr x} 12
 
-    ? {c1 lappend l e1} {Value 'e1' of parameter return-value not between 1 and 30}
+  ? {c1 lappend l e1} {Value 'e1' of parameter return-value not between 1 and 30}
 }
 
 nx::test configure -count 1000
-nx::test case converting-returns { 
+nx::test case converting-returns {
 
-    ::nx::methodParameterSlot object method type=sex {name value args} {
-        #puts stderr "[current] slot specific converter"
-	switch -glob $value {
-	    m* {return m}
-	    f* {return f}
-	    default {error "expected sex but got $value"}
-	}
+  ::nx::methodParameterSlot object method type=sex {name value args} {
+    #puts stderr "[current] slot specific converter"
+    switch -glob $value {
+      m* {return m}
+      f* {return f}
+      default {error "expected sex but got $value"}
     }
+  }
 
-    nx::Class create C {
-	:method bar-ok1 {a b} {return male}
-	:method bar-ok2 {a b} {return $a}
-	:method bar-nok {a b:integer} {return $b}
-	:alias set -frame object ::set
-	:create c1
-    }
+  nx::Class create C {
+    :method bar-ok1 {a b} {return male}
+    :method bar-ok2 {a b} {return $a}
+    :method bar-nok {a b:integer} {return $b}
+    :alias set -frame object ::set
+    :create c1
+  }
 
-    ::nsf::method::property C bar-ok1 returns sex
-    ::nsf::method::property C bar-ok2 returns sex
-    ::nsf::method::property C bar-nok returns sex
-    ::nsf::method::property C set returns sex
+  ::nsf::method::property C bar-ok1 returns sex
+  ::nsf::method::property C bar-ok2 returns sex
+  ::nsf::method::property C bar-nok returns sex
+  ::nsf::method::property C set returns sex
 
-    ? {c1 bar-ok1 1 2} male
-    ? {c1 bar-ok2 female 2} female
-    ? {c1 bar-nok 1 6} {expected sex but got 6}
+  ? {c1 bar-ok1 1 2} male
+  ? {c1 bar-ok2 female 2} female
+  ? {c1 bar-nok 1 6} {expected sex but got 6}
 
-    ? {c1 set x male} male
-    ? {c1 eval {set :x}} male
-    ? {c1 set x} male
+  ? {c1 set x male} male
+  ? {c1 eval {set :x}} male
+  ? {c1 set x} male
 
-    ? {c1 set x hugo} {expected sex but got hugo}
+  ? {c1 set x hugo} {expected sex but got hugo}
 
-    ::nsf::method::property C bar-ok1 returns sex,convert
-    ::nsf::method::property C bar-ok2 returns sex,convert
-    ::nsf::method::property C bar-nok returns sex,convert
-    ::nsf::method::property C set returns sex,convert
+  ::nsf::method::property C bar-ok1 returns sex,convert
+  ::nsf::method::property C bar-ok2 returns sex,convert
+  ::nsf::method::property C bar-nok returns sex,convert
+  ::nsf::method::property C set returns sex,convert
 
-    ? {c1 bar-ok1 1 2} m
-    ? {c1 bar-ok2 female 2} f
-    ? {c1 bar-nok 1 6} {expected sex but got 6}
+  ? {c1 bar-ok1 1 2} m
+  ? {c1 bar-ok2 female 2} f
+  ? {c1 bar-nok 1 6} {expected sex but got 6}
 
-    ? {c1 set x male} m
-    ? {c1 eval {set :x}} male
-    ? {c1 set x} m
+  ? {c1 set x male} m
+  ? {c1 eval {set :x}} male
+  ? {c1 set x} m
 
-    ? {c1 set x hugo} {expected sex but got hugo}
+  ? {c1 set x hugo} {expected sex but got hugo}
 }
 
 #
@@ -158,205 +158,236 @@
 ::nsf::configure checkresults false
 
 ::nx::test configure -count 1000
-::nx::test case int-returns-nocheck { 
-    nx::Class create C {
-	# scripted method without paramdefs
-	:method bar-ok1 {a b} {return 1}
-	:method bar-ok2 {a b} {return $a}
-	# scripted method with paramdefs
-	:method bar-nok {a b:integer} {return a}
-	# alias to tcl-cmd (no param defs)
-	:alias incr -frame object ::incr
-	:alias lappend -frame object ::lappend
-	:create c1
-    }
+::nx::test case int-returns-nocheck {
+  nx::Class create C {
+    # scripted method without paramdefs
+    :method bar-ok1 {a b} {return 1}
+    :method bar-ok2 {a b} {return $a}
+    # scripted method with paramdefs
+    :method bar-nok {a b:integer} {return a}
+    # alias to tcl-cmd (no param defs)
+    :alias incr -frame object ::incr
+    :alias lappend -frame object ::lappend
+    :create c1
+  }
 
-    ::nsf::method::property C bar-ok1 returns integer
-    ::nsf::method::property C bar-ok2 returns integer
-    ::nsf::method::property C bar-nok returns integer
-    ::nsf::method::property C incr returns integer
-    ::nsf::method::property C lappend returns integer
+  ::nsf::method::property C bar-ok1 returns integer
+  ::nsf::method::property C bar-ok2 returns integer
+  ::nsf::method::property C bar-nok returns integer
+  ::nsf::method::property C incr returns integer
+  ::nsf::method::property C lappend returns integer
 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} a
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} a
 
-    ? {c1 incr x} 1
-    ? {c1 incr x} 1002
+  ? {c1 incr x} 1
+  ? {c1 incr x} 1002
 
-    ? {c1 lappend l e1} e1
+  ? {c1 lappend l e1} e1
 
-    # query the returns value
-    ? {::nsf::method::property C lappend returns} integer
+  # query the returns value
+  ? {::nsf::method::property C lappend returns} integer
 
-    # reset it to empty
-    ? {::nsf::method::property C lappend returns ""} ""
+  # reset it to empty
+  ? {::nsf::method::property C lappend returns ""} ""
 
-    c1 eval {set :l e1}
-    # no checking on lappend
-    ? {c1 lappend l e2} "e1 e2"
+  c1 eval {set :l e1}
+  # no checking on lappend
+  ? {c1 lappend l e2} "e1 e2"
 
-    # query returns "", if there is no returns checking
-    ? {::nsf::method::property C lappend returns} ""
-    ? {::nsf::method::property ::nx::Class method returns} ""
+  # query returns "", if there is no returns checking
+  ? {::nsf::method::property C lappend returns} ""
+  ? {::nsf::method::property ::nx::Class method returns} ""
 }
 
 ::nx::test configure -count 10
-::nx::test case app-specific-returns-nocheck { 
+::nx::test case app-specific-returns-nocheck {
 
-    ::nx::methodParameterSlot object method type=range {name value arg} {
-	lassign [split $arg -] min max
-	if {$value < $min || $value > $max} {
-	    error "Value '$value' of parameter $name not between $min and $max"
-	}
-	return $value
+  ::nx::methodParameterSlot object method type=range {name value arg} {
+    lassign [split $arg -] min max
+    if {$value < $min || $value > $max} {
+      error "Value '$value' of parameter $name not between $min and $max"
     }
+    return $value
+  }
 
-    nx::Class create C {
-	:method bar-ok1 {a b} {return 1}
-	:method bar-ok2 {a b} {return $a}
-	:method bar-nok {a b:integer} {return a}
-	:alias incr -frame object ::incr
-	:alias lappend -frame object ::lappend
-	:create c1
-    }
+  nx::Class create C {
+    :method bar-ok1 {a b} {return 1}
+    :method bar-ok2 {a b} {return $a}
+    :method bar-nok {a b:integer} {return a}
+    :alias incr -frame object ::incr
+    :alias lappend -frame object ::lappend
+    :create c1
+  }
 
-    ::nsf::method::property C bar-ok1 returns range,arg=1-3
-    ::nsf::method::property C bar-ok2 returns range,arg=1-3
-    ::nsf::method::property C bar-nok returns range,arg=1-3
-    ::nsf::method::property C incr returns range,arg=1-30
-    ::nsf::method::property C lappend returns range,arg=1-30
+  ::nsf::method::property C bar-ok1 returns range,arg=1-3
+  ::nsf::method::property C bar-ok2 returns range,arg=1-3
+  ::nsf::method::property C bar-nok returns range,arg=1-3
+  ::nsf::method::property C incr returns range,arg=1-30
+  ::nsf::method::property C lappend returns range,arg=1-30
 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} a
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} a
 
-    ? {c1 incr x} 1
-    ? {c1 incr x} 12
+  ? {c1 incr x} 1
+  ? {c1 incr x} 12
 
-    ? {c1 lappend l e1} e1
+  ? {c1 lappend l e1} e1
 }
 
 ::nx::test configure -count 1000
-::nx::test case converting-returns-nocheck { 
+::nx::test case converting-returns-nocheck {
 
-    ::nx::methodParameterSlot object method type=sex {name value args} {
-        #puts stderr "[current] slot specific converter"
-	switch -glob $value {
-	    m* {return m}
-	    f* {return f}
-	    default {error "expected sex but got $value"}
-	}
+  ::nx::methodParameterSlot object method type=sex {name value args} {
+    #puts stderr "[current] slot specific converter"
+    switch -glob $value {
+      m* {return m}
+      f* {return f}
+      default {error "expected sex but got $value"}
     }
+  }
 
-    nx::Class create C {
-	:method bar-ok1 {a b} {return male}
-	:method bar-ok2 {a b} {return $a}
-	:method bar-nok {a b:integer} {return $b}
-	:alias set -frame object ::set
-	:create c1
-    }
+  nx::Class create C {
+    :method bar-ok1 {a b} {return male}
+    :method bar-ok2 {a b} {return $a}
+    :method bar-nok {a b:integer} {return $b}
+    :alias set -frame object ::set
+    :create c1
+  }
 
-    #
-    # turn off checker
-    #
-    ::nsf::method::property C bar-ok1 returns sex
-    ::nsf::method::property C bar-ok2 returns sex
-    ::nsf::method::property C bar-nok returns sex
-    ::nsf::method::property C set returns sex
+  #
+  # turn off checker
+  #
+  ::nsf::method::property C bar-ok1 returns sex
+  ::nsf::method::property C bar-ok2 returns sex
+  ::nsf::method::property C bar-nok returns sex
+  ::nsf::method::property C set returns sex
 
-    ? {c1 bar-ok1 1 2} male
-    ? {c1 bar-ok2 female 2} female
-    ? {c1 bar-nok 1 6} 6
+  ? {c1 bar-ok1 1 2} male
+  ? {c1 bar-ok2 female 2} female
+  ? {c1 bar-nok 1 6} 6
 
-    ? {c1 set x male} male
-    ? {c1 eval {set :x}} male
-    ? {c1 set x} male
+  ? {c1 set x male} male
+  ? {c1 eval {set :x}} male
+  ? {c1 set x} male
 
-    ? {c1 set x hugo} hugo
+  ? {c1 set x hugo} hugo
 
-    #
-    # don't turn off converter
-    #
-    ::nsf::method::property C bar-ok1 returns sex,convert
-    ::nsf::method::property C bar-ok2 returns sex,convert
-    ::nsf::method::property C bar-nok returns sex,convert
-    ::nsf::method::property C set returns sex,convert
+  #
+  # don't turn off converter
+  #
+  ::nsf::method::property C bar-ok1 returns sex,convert
+  ::nsf::method::property C bar-ok2 returns sex,convert
+  ::nsf::method::property C bar-nok returns sex,convert
+  ::nsf::method::property C set returns sex,convert
 
-    ? {c1 bar-ok1 1 2} m
-    ? {c1 bar-ok2 female 2} f
-    ? {c1 bar-nok 1 6} {expected sex but got 6}
+  ? {c1 bar-ok1 1 2} m
+  ? {c1 bar-ok2 female 2} f
+  ? {c1 bar-nok 1 6} {expected sex but got 6}
 
-    ? {c1 set x male} m
-    ? {c1 eval {set :x}} male
-    ? {c1 set x} m
+  ? {c1 set x male} m
+  ? {c1 eval {set :x}} male
+  ? {c1 set x} m
 
-    ? {c1 set x hugo} {expected sex but got hugo}
+  ? {c1 set x hugo} {expected sex but got hugo}
 }
 
 
 ::nsf::configure checkresults true
 
-::nx::test case int-returns-sugar { 
-    nx::Class create C {
-	# scripted method without paramdefs
-	:method bar-ok1 {a b} -returns integer {return 1}
-	:method bar-ok2 {a b} -returns integer {return $a}
-	# scripted method with paramdefs
-	:method bar-nok {a b:integer} -returns integer {return a}
-	# alias to tcl-cmd (no param defs)
-	:alias incr -returns integer -frame object ::incr
-	:alias lappend -returns integer -frame object ::lappend
-	:forward ++ -returns integer ::expr 1 +
-	:forward | -returns integer ::append _ 
-	:public object method instances {} -returns object,1..n {:info instances}
-	:create c1
-    }
+::nx::test case int-returns-sugar {
+  nx::Class create C {
+    # scripted method without paramdefs
+    :method bar-ok1 {a b} -returns integer {return 1}
+    :method bar-ok2 {a b} -returns integer {return $a}
+    # scripted method with paramdefs
+    :method bar-nok {a b:integer} -returns integer {return a}
+    # alias to tcl-cmd (no param defs)
+    :alias incr -returns integer -frame object ::incr
+    :alias lappend -returns integer -frame object ::lappend
+    :forward ++ -returns integer ::expr 1 +
+    :forward | -returns integer ::append _
+    :public object method instances {} -returns object,1..n {:info instances}
+    :create c1
+  }
 
-    package req nx::serializer
-    set s [C serialize]
+  package req nx::serializer
+  set s [C serialize]
   puts $s
-    ? [list set _ [regsub -all returns $s returns s]] 8 "occurrences of returns"
+  ? [list set _ [regsub -all returns $s returns s]] 8 "occurrences of returns"
 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 ++ 1000} 1001
-    ? {c1 | a} {expected integer but got "a" as return value}
-    ? {::nsf::method::property ::C ::nsf::classes::C::bar-nok returns} integer
-    ? {c1 bar-nok 1 2} {expected integer but got "a" as return value}
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 ++ 1000} 1001
+  ? {c1 | a} {expected integer but got "a" as return value}
+  ? {::nsf::method::property ::C ::nsf::classes::C::bar-nok returns} integer
+  ? {c1 bar-nok 1 2} {expected integer but got "a" as return value}
 
-    ? {C instances} ::c1
+  ? {C instances} ::c1
 
-    ? {c1 incr x} 1
-    ? {c1 incr x} 1002
+  ? {c1 incr x} 1
+  ? {c1 incr x} 1002
 
-    ? {c1 lappend l e1} {expected integer but got "e1" as return value}
+  ? {c1 lappend l e1} {expected integer but got "e1" as return value}
 
-    # query the returns value
-    ? {::nsf::method::property C lappend returns} integer
+  # query the returns value
+  ? {::nsf::method::property C lappend returns} integer
 
-    # reset it to empty
-    ? {::nsf::method::property C lappend returns ""} ""
-    ? {::nsf::method::property C bar-ok1 returns ""} ""
-    ? {::nsf::method::property C bar-ok2 returns ""} ""
-    ? {::nsf::method::property C bar-nok returns ""} ""
-    ? {::nsf::method::property C ++ returns ""} ""
-    ? {::nsf::method::property C | returns ""} ""
+  # reset it to empty
+  ? {::nsf::method::property C lappend returns ""} ""
+  ? {::nsf::method::property C bar-ok1 returns ""} ""
+  ? {::nsf::method::property C bar-ok2 returns ""} ""
+  ? {::nsf::method::property C bar-nok returns ""} ""
+  ? {::nsf::method::property C ++ returns ""} ""
+  ? {::nsf::method::property C | returns ""} ""
 
-    # no checking 
-    ? {c1 bar-ok1 1 2} 1
-    ? {c1 bar-ok2 1 2} 1
-    ? {c1 bar-nok 1 2} a
-    ? {c1 lappend l e2} "e1 e2"
-    ? {c1 ++ 1000} 1001
-    ? {c1 | a} "a"
+  # no checking
+  ? {c1 bar-ok1 1 2} 1
+  ? {c1 bar-ok2 1 2} 1
+  ? {c1 bar-nok 1 2} a
+  ? {c1 lappend l e2} "e1 e2"
+  ? {c1 ++ 1000} 1001
+  ? {c1 | a} "a"
 
-    # query returns "", if there is no returns checking
-    ? {::nsf::method::property C lappend returns} ""
-    ? {::nsf::method::property ::nx::Class method returns} ""
+  # query returns "", if there is no returns checking
+  ? {::nsf::method::property C lappend returns} ""
+  ? {::nsf::method::property ::nx::Class method returns} ""
 
 }
 
+::nx::test case int-returns-string-checks {
+  ::nx::Class create TestOK {
+    #
+    # strings test with "string is alpha" checker
+    #
+    :public method get1 {} -returns alpha { return a }
+    :public method get2 {} -returns alpha { return 1 }
+    :public method get3 {} -returns alpha,1..n { return {a b c} }
+    :public method get4 {} -returns alpha,1..n { return {a 1 c} }
+    #
+    # built-in checker
+    #
+    :public method get5 {} -returns integer { return 2 }
+    :public method get6 {} -returns integer { return a }
+    :public method get7 {} -returns integer,1..n { return {1 2 3} }
+    :public method get8 {} -returns integer,1..n { return {1 2 a} }
+
+    :create a
+  }
+
+  ? {a get1} a
+  ? {a get2} {expected alpha but got "1" as return value}
+  ? {a get3} {a b c}
+  ? {a get4} {invalid value in "a 1 c": expected alpha but got "1" as return value}
+  ? {a get5} 2
+  ? {a get6} {expected integer but got "a" as return value}
+  ? {a get7} {1 2 3}
+  ? {a get8} {invalid value in "1 2 a": expected integer but got "a" as return value}
+}
+
+
 ::nx::test case empty-paramdefs-robustedness {
   ::nx::Object create ku {
     # 1: Create an empty or checker-free parameter spec
@@ -384,4 +415,3 @@
 #    tcl-indent-level: 2
 #    indent-tabs-mode: nil
 # End:
-