Remove support for anonymous objects.

Anonymous objects were initially implemented as a way of failing
gracefully in the case when no explicit name was supplied.  However, an
anonymous object does not make much sense.

sympy/categories/baseclasses.py

@@ -21,40 +21,34 @@ class Object(Basic):
 
     While concrete categories may have some concrete SymPy classes as
     object types, in abstract categories only the name of an object is
-    known.
+    known.  Anonymous objects are not allowed.
 
-    Two objects with the same name are the same object.  An unnamed
-    object is not equal to any other object.
+    Two objects with the same name are the same object.
 
     Examples
     ========
 
     >>> from sympy.categories import Object
     >>> Object("A") == Object("A")
     True
-    >>> Object("A") == Object("")
-    False
 
     """
-    def __init__(self, name=""):
+    def __init__(self, name):
+        if not name:
+            raise ValueError("Anonymous Objects are not allowed.")
+
         self.name = name
 
     def __eq__(self, obj):
         if not isinstance(obj, Object):
             return False
 
-        if (not obj.name) or (not self.name):
-            return False
-
         return self.name == obj.name
 
     def __ne__(self, obj):
         if not isinstance(obj, Object):
             return True
 
-        if (not obj.name) or (not self.name):
-            return True
-
         return self.name != obj.name
 
     def __hash__(self):

sympy/categories/tests/test_baseclasses.py

@@ -9,13 +9,13 @@ def test_object():
 
     assert A == Object("A")
     assert A != Object("A1")
-    assert Object("") != A
-    assert Object("") != Object("")
 
     assert hash(A) == hash(Object("A"))
 
     assert A != None
 
+    raises(ValueError, lambda: Object(""))
+
 def test_morphism():
     A = Object("A")
     B = Object("B")

sympy/printing/latex.py

@@ -1182,10 +1182,7 @@ def _print_DMF(self, p):
         return self._print_DMP(p)
 
     def _print_Object(self, object):
-        if object.name:
-            return self._print(Symbol(object.name))
-        else:
-            return "\\bullet"
+        return self._print(Symbol(object.name))
 
     def _print_Morphism(self, morphism):
         domain = self._print(morphism.domain)

sympy/printing/pretty/pretty.py

@@ -1447,13 +1447,7 @@ def _print_DMF(self, p):
         return self._print_DMP(p)
 
     def _print_Object(self, object):
-        if object.name:
-            return self._print(pretty_symbol(object.name))
-        else:
-            if self._use_unicode:
-                return self._print(u"\u2022")
-            else:
-                return self._print(".")
+        return self._print(pretty_symbol(object.name))
 
     def _print_Morphism(self, morphism):
         arrow = "->"

sympy/printing/pretty/tests/test_pretty.py

@@ -3718,10 +3718,7 @@ def test_categories():
     assert pretty(K1) == "K1"
     assert upretty(K1) == u"K₁"
 
-    # Some further tests for anonymous objects and morphisms.
-    assert pretty(Object("")) == "."
-    assert upretty(Object("")) == u"•"
-
+    # Some further tests for anonymous morphisms.
     h = Morphism(A2, A3, "").compose(Morphism(A1, A2, ""), "h")
     assert pretty(h) == "h:A1->A3"
     assert upretty(h) == u"h:A₁→A₃"

sympy/printing/tests/test_latex.py

@@ -589,8 +589,6 @@ def test_categories():
 
     assert latex(K1) == "\mathbf{K_{1}}"
 
-    assert latex(Object("")) == "\\bullet"
-
     h = Morphism(A2, A3, "").compose(Morphism(A1, A2, ""), "h")
     assert latex(h) == "h:A_{1}\\rightarrow A_{3}"