Index: TODO
===================================================================
diff -u -r9ab7249b16aeb0ea906e3d614fee429edab1cfda -r97e0a189f00e655455aa3a48e44ab61f700eab58
--- TODO	(.../TODO)	(revision 9ab7249b16aeb0ea906e3d614fee429edab1cfda)
+++ TODO	(.../TODO)	(revision 97e0a189f00e655455aa3a48e44ab61f700eab58)
@@ -3258,6 +3258,10 @@
     accessors are deactivated for this attribute)
   * extended regression test
 
+- nx.tcl: extended object-parameter "switch" implementation:
+  now, accessors of type boolean are created, when type "switch" is used.
+
+
 TODO:
 
  - strange refcounting bug in 8.6b2 bug-is-86.tcl
Index: library/nx/nx.tcl
===================================================================
diff -u -r9ab7249b16aeb0ea906e3d614fee429edab1cfda -r97e0a189f00e655455aa3a48e44ab61f700eab58
--- library/nx/nx.tcl	(.../nx.tcl)	(revision 9ab7249b16aeb0ea906e3d614fee429edab1cfda)
+++ library/nx/nx.tcl	(.../nx.tcl)	(revision 97e0a189f00e655455aa3a48e44ab61f700eab58)
@@ -817,7 +817,6 @@
 
     if {[info exists type]} {
       #if {$type eq "switch"} {error "switch is not allowed as type for object parameter $name"}
-      if {$type eq "switch"} {set opt(-accessor) false}
       lappend opts -type $type
     }
     lappend opts {*}[array get opt]
@@ -1415,13 +1414,15 @@
   } {
     set options ""
     if {[info exists :type]} {
-      if {${:type} eq "initcmd"} {
+      set type ${:type}
+      if {$type eq "switch" && !$forObjectParameter} {set type boolean}
+      if {$type eq "initcmd"} {
 	lappend options initcmd
-      } elseif {[string match ::* ${:type}]} {
-	lappend options [expr {[::nsf::is metaclass ${:type}] ? "class" : "object"}] type=${:type}
+      } elseif {[string match ::* $type]} {
+	lappend options [expr {[::nsf::is metaclass $type] ? "class" : "object"}] type=$type
       } else {
-	lappend options ${:type}
-	if {${:type} ni [list "" "switch" \
+	lappend options $type
+	if {$type ni [list "" "switch" \
 			     "boolean" "integer" "object" "class" \
 			     "metaclass" "baseclass" "parameter" \
 			     "alnum" "alpha" "ascii" "control" "digit" "double" \
@@ -1665,17 +1666,21 @@
       lassign [::nx::MetaSlot parseParameterSpec -class $class $spec] \
 	  name parameterOptions class opts
 
+      set isSwitch [regsub {\mswitch\M} $parameterOptions boolean parameterOptions]
       if {[info exists value]} {
 	if {[info exists :$name] && !$nocomplain} {
 	  error "Object [self] has already an instance variable named '$name'"
 	}
 	if {$parameterOptions ne ""} {
-	  #puts stderr "::nsf::is $parameterOptions $value"
+	  #puts stderr "*** ::nsf::is $parameterOptions $value // opts=$opts"
+	  # we rely here that the nsf::is error message expresses the implementation limits
 	  ::nsf::is -complain $parameterOptions $value
 	} else {
 	  set name $spec
 	}
 	set :$name $value
+      } elseif {$isSwitch} {
+	set :$name 0
       } else {
 	error "Variable definition for '$name' (without value and accessor) is useless"
       }
Index: tests/parameters.test
===================================================================
diff -u -r9ab7249b16aeb0ea906e3d614fee429edab1cfda -r97e0a189f00e655455aa3a48e44ab61f700eab58
--- tests/parameters.test	(.../parameters.test)	(revision 9ab7249b16aeb0ea906e3d614fee429edab1cfda)
+++ tests/parameters.test	(.../parameters.test)	(revision 97e0a189f00e655455aa3a48e44ab61f700eab58)
@@ -499,7 +499,7 @@
     {d "literal $d"}
   }
 
-  ? {Bar attribute ss:switch} ""
+  ? {Bar attribute ss:switch} "::nsf::classes::Bar::ss"
 
   Bar create bar1
   #puts stderr [bar1 objectparameter]
@@ -2064,44 +2064,59 @@
   ? {lsort [o info vars]} {}
 }
 
-#
-# Testing object parameter switch
-#
 
 nx::Test case object-parameter-switch {
 
+  # Create a class with an attribute of type switch and an instance of
+  # the class
   ? {::nx::Class create C {
     :attribute foo:switch
     :create c1
   }} "::C"
 
-  # when the parameter is not specified, the default is false, an
-  # instance variable is set
+  # When the object parameter is not specified at creation time, the
+  # default is false, an instance variable is set with this value
   ? {lsort [c1 info vars]} {foo}
   ? {c1 eval {set :foo}} {0}
 
-  # when the parameter is specified, the instance variable has a value
-  # of true (i.e. 1)
+  # Object parameter of type "switch" are more tricky, since e.g. a
+  # setter with 0 arguments is a getter. When a setter is built, it
+  # uses the parameter type boolean instead.
+  ? {C info methods} "foo"
+  ? {c1 info lookup method foo} "::nsf::classes::C::foo"
+  ? {c1 foo} 0
+  ? {c1 foo 1} 1
+  ? {c1 foo} 1
+
+  # When the object parameter is specified, the instance variable has
+  # a value of true (i.e. 1)
   C create c2 -foo
   ? {lsort [c2 info vars]} {foo}
   ? {c2 eval {set :foo}} {1}
 
-  # One can pass false as well
+  # One can pass false (and other values) with the = notation as well
   C create c3 -foo=false
   ? {lsort [c3 info vars]} {foo}
   ? {c3 eval {set :foo}} {false}
 
-  # The inverted case, 
-  C attribute {foo2:switch true}
+  # In the inverted case, the switch has a default of "true". If the
+  # switch is specified, the valus is "false"
+  C attribute {foo2:switch 1}
   C create c4
   ? {lsort [c4 info vars]} {foo foo2}
-  ? {c4 eval {set :foo2}} {true}
+  ? {c4 eval {set :foo2}} {1}
   C create c5 -foo2
   ? {lsort [c5 info vars]} {foo foo2}
   ? {c5 eval {set :foo2}} {0}
 
-  # Object case, not very useful, boolean would be perfectly fine.
+  # Object case: variables of type "switch" are like variables of type
+  # boolean, except that without the specified value argument
+  # (variable foo below), it sets the the variable to "false".
   ? {::nx::Object create o1 {
-    :variable bar:switch 0
-  }} {invalid value constraints "switch"}
+    :variable foo:switch
+    :variable bar:switch 1
+  }} ::o1
+  ? {o1 eval {set :foo}} 0
+  ? {o1 eval {set :bar}} 1
+
 }
\ No newline at end of file