Overriding the name Parameter is taken into account at the class an…

…d instance level (#740)

param/parameterized.py

@@ -2844,8 +2844,7 @@ def __init__(mcs, name, bases, dict_):
         """
         type.__init__(mcs, name, bases, dict_)
 
-        # Give Parameterized classes a useful 'name' attribute.
-        mcs.name = name
+        mcs.__set_name(name, dict_)
 
         mcs._parameters_state = {
             "BATCH_WATCH": False, # If true, Event and watcher objects are queued.
@@ -2898,6 +2897,37 @@ def __init__(mcs, name, bases, dict_):
         if docstring_signature:
             mcs.__class_docstring_signature()
 
+    def __set_name(mcs, name, dict_):
+        """
+        Give Parameterized classes a useful 'name' attribute that is by
+        default the class name, unless a class in the hierarchy has defined
+        a `name` String Parameter with a defined `default` value, in which case
+        that value is used to set the class name.
+        """
+        mcs.__renamed = False
+        name_param = dict_.get("name", None)
+        if name_param is not None:
+            if not type(name_param) is String:
+                raise TypeError(
+                    f"Parameterized class {name!r} cannot override "
+                    f"the 'name' Parameter with type {type(name_param)}. "
+                    "Overriding 'name' is only allowed with a 'String' Parameter."
+                )
+            if name_param.default:
+                mcs.name = name_param.default
+                mcs.__renamed = True
+            else:
+                mcs.name = name
+        else:
+            classes = classlist(mcs)[::-1]
+            found_renamed = False
+            for c in classes:
+                if getattr(c, "_ParameterizedMetaclass__renamed", False):
+                    found_renamed = True
+                    break
+            if not found_renamed:
+                mcs.name = name
+
     def __class_docstring_signature(mcs, max_repr_len=15):
         """
         Autogenerate a keyword signature in the class docstring for
@@ -3038,14 +3068,15 @@ def __param_inheritance(mcs,param_name,param):
             setattr(param,'objtype',mcs)
             del slots['objtype']
 
+        supers = classlist(mcs)[::-1]
+
         # instantiate is handled specially
-        for superclass in classlist(mcs)[::-1]:
+        for superclass in supers:
             super_param = superclass.__dict__.get(param_name)
             if isinstance(super_param, Parameter) and super_param.instantiate is True:
                 param.instantiate=True
         del slots['instantiate']
 
-        supers = classlist(mcs)[::-1]
         callables = {}
         for slot in slots.keys():
             superclasses = iter(supers)
@@ -3363,7 +3394,10 @@ def __init__(self, **params):
         self._param_watchers = {}
         self._dynamic_watchers = defaultdict(list)
 
-        self.param._generate_name()
+        # Skip generating a custom instance name when a class in the hierarchy
+        # has overriden the default of the `name` Parameter.
+        if self.param.name.default == self.__class__.__name__:
+            self.param._generate_name()
         self.param._setup_params(**params)
         object_count += 1
 

tests/testparameterizedobject.py

@@ -111,15 +111,158 @@ class P(param.Parameterized):
 
         p = P()
 
-        match = re.fullmatch(r'P\w{5}', p.name)
-        assert match is not None
+        assert p.name == 'Other'
 
     def test_parameter_name_fixed(self):
         testpo = TestPO()
 
         with pytest.raises(AttributeError):
             testpo.param.const.name = 'notconst'
 
+    def test_name_overriden(self):
+        class P(param.Parameterized):
+            name = param.String(default='other')
+
+        assert P.name == 'other'
+
+        p = P()
+
+        assert p.name == 'other'
+
+    def test_name_overriden_without_default(self):
+        class A(param.Parameterized):
+            pass
+        class B(param.Parameterized):
+            name = param.String(doc='some help')
+
+        class C(B):
+            pass
+
+        assert B.name == 'B'
+        assert B.param.name.doc == 'some help'
+        assert C.name == 'C'
+        assert C.param.name.doc == 'some help'
+
+    def test_name_overriden_constructor(self):
+        class P(param.Parameterized):
+            name = param.String(default='other')
+
+        p = P(name='another')
+
+        assert p.name == 'another'
+
+    def test_name_overriden_subclasses(self):
+        class P(param.Parameterized):
+            name = param.String(default='other')
+
+        class Q(P):
+            pass
+
+        class R(Q):
+            name = param.String(default='yetanother')
+
+        assert Q.name == 'other'
+
+        q1 = Q()
+
+        assert q1.name == 'other'
+
+        q2 = Q(name='another')
+
+        assert q2.name == 'another'
+
+        assert R.name == 'yetanother'
+
+        r1 = R()
+
+        assert r1.name == 'yetanother'
+
+        r2 = R(name='last')
+
+        assert r2.name == 'last'
+
+
+    def test_name_overriden_subclasses_name_set(self):
+        class P(param.Parameterized):
+            name = param.String(default='other')
+
+        class Q(P):
+            pass
+
+        P.name = 'another'
+
+        assert Q.name == 'another'
+
+        Q.name = 'yetanother'
+
+        assert Q.name == 'yetanother'
+
+        q = Q()
+
+        assert q.name == 'yetanother'
+
+    def test_name_overriden_error_not_String(self):
+
+        msg = "Parameterized class 'P' cannot override the 'name' Parameter " \
+              "with type <class 'str'>. Overriding 'name' is only allowed with " \
+              "a 'String' Parameter."
+
+        with pytest.raises(TypeError, match=msg):
+            class P(param.Parameterized):
+                name = 'other'
+
+        msg = "Parameterized class 'P' cannot override the 'name' Parameter " \
+              "with type <class 'param.parameterized.Parameter'>. Overriding 'name' " \
+              "is only allowed with a 'String' Parameter."
+
+        with pytest.raises(TypeError, match=msg):
+            class P(param.Parameterized):
+                name = param.Parameter(default='other')
+
+    def test_name_complex_hierarchy(self):
+        class Mixin1: pass
+        class Mixin2: pass
+        class Mixin3(param.Parameterized): pass
+
+        class A(param.Parameterized, Mixin1): pass
+        class B(A): pass
+        class C(B, Mixin2): pass
+        class D(C, Mixin3): pass
+
+        assert A.name == 'A'
+        assert B.name == 'B'
+        assert C.name == 'C'
+        assert D.name == 'D'
+
+    def test_name_overriden_complex_hierarchy(self):
+        class Mixin1: pass
+        class Mixin2: pass
+        class Mixin3(param.Parameterized): pass
+
+        class A(param.Parameterized, Mixin1): pass
+        class B(A):
+            name = param.String(default='other')
+
+        class C(B, Mixin2):
+            name = param.String(default='another')
+
+        class D(C, Mixin3): pass
+
+        assert A.name == 'A'
+        assert B.name == 'other'
+        assert C.name == 'another'
+        assert D.name == 'another'
+
+    def test_name_overriden_multiple(self):
+        class A(param.Parameterized):
+            name = param.String(default='AA')
+        class B(param.Parameterized):
+            name = param.String(default='BB')
+
+        class C(A, B): pass
+
+        assert C.name == 'AA'
+
     def test_constant_parameter(self):
         """Test that you can't set a constant parameter after construction."""
         testpo = TestPO(const=17)