X-Git-Url: http://nitlanguage.org

diff --git a/lib/poset.nit b/lib/poset.nit
index c6fd1d2..93afcf1 100644
--- a/lib/poset.nit
+++ b/lib/poset.nit
@@ -71,7 +71,7 @@ module poset
 #
 # Thanks to the `[]` method, elements can be considered relatively to the poset.
 # SEE `POSetElement`
-class POSet[E: Object]
+class POSet[E]
 	super Collection[E]
 	super Comparator
 
@@ -226,21 +226,26 @@ class POSet[E: Object]
 
 	# Write the POSet as a graphviz digraph.
 	#
-	# Nodes are identified with their `to_s`.
+	# Nodes are labeled with their `to_s` so homonymous nodes may appear.
 	# Edges are unlabeled.
-	fun write_dot(f: OStream)
+	fun write_dot(f: Writer)
 	do
 		f.write "digraph \{\n"
+		var ids = new HashMap[E, Int]
+		for x in elements.keys do
+			ids[x] = ids.length
+		end
 		for x in elements.keys do
 			var xstr = x.to_s.escape_to_dot
-			f.write "\"{xstr}\";\n"
+			var nx = "n{ids[x]}"
+			f.write "{nx}[label=\"{xstr}\"];\n"
 			var xe = self.elements[x]
 			for y in xe.dtos do
-				var ystr = y.to_s.escape_to_dot
+				var ny = "n{ids[y]}"
 				if self.has_edge(y,x) then
-					f.write "\"{xstr}\" -> \"{ystr}\"[dir=both];\n"
+					f.write "{nx} -> {ny}[dir=both];\n"
 				else
-					f.write "\"{xstr}\" -> \"{ystr}\";\n"
+					f.write "{nx} -> {ny};\n"
 				end
 			end
 		end
@@ -253,8 +258,7 @@ class POSet[E: Object]
 	# See `write_dot` for details.
 	fun show_dot
 	do
-		var f = new OProcess("dot", "-Txlib")
-		f.write "\}\n"
+		var f = new ProcessWriter("dot", "-Txlib")
 		write_dot(f)
 		f.close
 		f.wait
@@ -366,14 +370,16 @@ end
 #
 # For instance, one common usage is to add a specific attribute for each poset a class belong.
 #
-#     class Thing
-#         var in_some_relation: POSetElement[Thing]
-#         var in_other_relation: POSetElement[Thing]
-#     end
-#     var t: Thing # ...
-#     t.in_some_relation.greaters
-#
-class POSetElement[E: Object]
+# ~~~nitish
+# class Thing
+#     var in_some_relation: POSetElement[Thing]
+#     var in_other_relation: POSetElement[Thing]
+# end
+# var t: Thing
+# # ...
+# t.in_some_relation.greaters
+# ~~~
+class POSetElement[E]
 	# The poset self belong to
 	var poset: POSet[E]