[visitor] Fix up attrs visiting

Lib/fontTools/misc/visitor.py

@@ -8,22 +8,19 @@ class Visitor(object):
     defaultStop = False
 
     @classmethod
-    def _register(celf, clazzes, attrs=(None,)):
+    def _register(celf, clazzes_attrs):
         assert celf != Visitor, "Subclass Visitor instead."
         if "_visitors" not in celf.__dict__:
             celf._visitors = {}
+
+        def wrapper(method):
+            assert method.__name__ == "visit"
+            for clazzes,attrs in clazzes_attrs:
                 if type(clazzes) != tuple:
                     clazzes = (clazzes,)
                 if type(attrs) == str:
                     attrs = (attrs,)
-
-        def wrapper(method):
-            assert method.__name__ == "visit"
-            done = []
                 for clazz in clazzes:
-                if clazz in done:
-                    continue  # Support multiple names of a clazz
-                done.append(clazz)
                     _visitors = celf._visitors.setdefault(clazz, {})
                     for attr in attrs:
                         assert attr not in _visitors, (
@@ -37,17 +34,24 @@ class Visitor(object):
 
     @classmethod
     def register(celf, clazzes):
-        return celf._register(clazzes)
+        if type(clazzes) != tuple:
+            clazzes = (clazzes,)
+        return celf._register([(clazzes, (None,))])
 
     @classmethod
     def register_attr(celf, clazzes, attrs):
-        return celf._register(clazzes, attrs)
+        clazzes_attrs = []
+        if type(clazzes) != tuple:
+            clazzes = (clazzes,)
+        if type(attrs) == str:
+            attrs = (attrs,)
+        for clazz in clazzes:
+            clazzes_attrs.append((clazz, attrs))
+        return celf._register(clazzes_attrs)
 
     @classmethod
     def register_attrs(celf, clazzes_attrs):
-        for clazz, attrs in clazzes_attrs:
+        return celf._register(clazzes_attrs)
-            celf._register(clazz, attrs)
-        return lambda _: None
 
     @classmethod
     def _visitorsFor(celf, thing, _default={}):

Snippets/scale-upem.py

@@ -41,7 +41,6 @@ class ScalerVisitor(TTVisitor):
                 "ySuperscriptXOffset",
                 "ySuperscriptYOffset",
                 "yStrikeoutSize",
-                "yStrikeoutSize",
                 "yStrikeoutPosition",
                 "sTypoAscender",
                 "sTypoDescender",
@@ -130,3 +129,5 @@ if __name__ == "__main__":
 
     visitor = ScalerVisitor(new_upem / upem)
     visitor.visit(font)
+
+    font.save("out.ttf")