lib/poset: fix warnings and a typo

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/poset.nit b/lib/poset.nit
index f7d6283..1c2a349 100644 (file)
--- a/lib/poset.nit
+++ b/lib/poset.nit
@@ -254,7 +254,7 @@ class POSet[E]
                        ids[x] = ids.length
                end
                for x in elements.keys do
-                       var xstr = x.to_s.escape_to_dot
+                       var xstr = (x or else "null").to_s.escape_to_dot
                        var nx = "n{ids[x]}"
                        f.write "{nx}[label=\"{xstr}\"];\n"
                        var xe = self.elements[x]
@@ -309,7 +309,7 @@ class POSet[E]
        # ~~~~
        #
        # Note that the linear extension is stable, unless a new node or a new edge is added.
-       redef fun compare(a, b: E): Int
+       redef fun compare(a, b)
        do
                var ae = self.elements[a]
                var be = self.elements[b]
@@ -486,7 +486,7 @@ class POSet[E]
        end
 end
 
-# View of an objet in a poset
+# View of an object in a poset
 # This class is a helper to handle specific queries on a same object
 #
 # For instance, one common usage is to add a specific attribute for each poset a class belong.