Reviewer changes: delete is_cdvr functions and friends, add abstract_…

…method to precision_absolute and precision_relative, add some tests

src/sage/categories/complete_discrete_valuation.py

@@ -22,6 +22,18 @@
 class CompleteDiscreteValuationRings(Category_singleton):
     """
     The category of complete discrete valuation rings
+
+    EXAMPLES::
+
+        sage: Zp(7) in CompleteDiscreteValuationRings()
+        True
+        sage: QQ in CompleteDiscreteValuationRings()
+        False
+        sage: QQ[['u']] in CompleteDiscreteValuationRings()
+        True
+        sage: Qp(7) in CompleteDiscreteValuationRings()
+        False
+        sage: TestSuite(CompleteDiscreteValuationRings()).run()
     """
     def super_categories(self):
         """
@@ -32,23 +44,8 @@ def super_categories(self):
         """
         return [DiscreteValuationRings()]
 
-    class ParentMethods:
-        def is_cdvr(self):
-            """
-            Return True if this ring is complete DVR.
-
-            EXAMPLES::
-
-                sage: Zp(7).is_cdvr()
-                True
-
-                sage: K.<u> = QQ[[]]
-                sage: K.is_cdvr()
-                True
-            """
-            return True
-
     class ElementMethods:
+        @abstract_method
         def precision_absolute(self):
             """
             Return the absolute precision of this element.
@@ -61,8 +58,8 @@ def precision_absolute(self):
                 sage: x.precision_absolute()
                 21
             """
-            pass
 
+        @abstract_method
         def precision_relative(self):
             """
             Return the relative precision of this element.
@@ -75,12 +72,22 @@ def precision_relative(self):
                 sage: x.precision_relative()
                 20
             """
-            pass
-
 
 class CompleteDiscreteValuationFields(Category_singleton):
     """
     The category of complete discrete valuation fields
+
+    EXAMPLES::
+
+        sage: Zp(7) in CompleteDiscreteValuationFields()
+        False
+        sage: QQ in CompleteDiscreteValuationFields()
+        False
+        sage: LaurentSeriesRing(QQ,'u') in CompleteDiscreteValuationFields()
+        True
+        sage: Qp(7) in CompleteDiscreteValuationFields()
+        True
+        sage: TestSuite(CompleteDiscreteValuationFields()).run()
     """
 
     def super_categories(self):
@@ -92,20 +99,8 @@ def super_categories(self):
         """
         return [DiscreteValuationFields()]
 
-    class ParentMethods:
-        def is_cdvf(self):
-            """
-            Return True if this ring is a field equipped with a discrete valuation
-            for which it is complete.
-
-            EXAMPLES::
-
-                sage: Qp(7).is_cdvf()
-                True
-            """
-            return True
-
     class ElementMethods:
+        @abstract_method
         def precision_absolute(self):
             """
             Return the absolute precision of this element.
@@ -118,8 +113,8 @@ def precision_absolute(self):
                 sage: x.precision_absolute()
                 21
             """
-            pass
 
+        @abstract_method
         def precision_relative(self):
             """
             Return the relative precision of this element.
@@ -132,4 +127,3 @@ def precision_relative(self):
                 sage: x.precision_relative()
                 20
             """
-            pass

src/sage/categories/discrete_valuation.py

@@ -24,6 +24,12 @@
 class DiscreteValuationRings(Category_singleton):
     """
     The category of discrete valuation rings
+
+    EXAMPLES::
+
+        sage: GF(7)[['x']] in DiscreteValuationRings()
+        True
+        sage: TestSuite(DiscreteValuationRings()).run()
     """
     def super_categories(self):
         """
@@ -65,21 +71,6 @@ def residue_field(self):
                 Rational Field
             """
 
-        def is_dvr(self):
-            """
-            Return True if this ring is DVR.
-
-            EXAMPLES::
-
-                sage: Zp(7).is_dvr()
-                True
-
-                sage: K.<u> = QQ[[]]
-                sage: K.is_dvr()
-                True
-            """
-            return True
-
     class ElementMethods:
         @abstract_method
         def valuation(self):
@@ -139,6 +130,12 @@ def lcm(self,other):
 class DiscreteValuationFields(Category_singleton):
     """
     The category of discrete valuation fields
+
+    EXAMPLES::
+
+        sage: Qp(7) in DiscreteValuationFields()
+        True
+        sage: TestSuite(DiscreteValuationFields()).run()
     """
 
     def super_categories(self):
@@ -178,17 +175,6 @@ def residue_field(self):
                 Rational Field
             """
 
-        def is_dvf(self):
-            """
-            Return True if this ring is a field equipped with a discrete valuation.
-
-            EXAMPLES::
-
-                sage: Qp(7).is_cdvf()
-                True
-            """
-            return True
-
     class ElementMethods:
         @abstract_method
         def valuation(self):