Replace None with _Undefined in constructors, and move validation to …

…the ParameterizedMetaclass

param/__init__.py

@@ -25,7 +25,7 @@
 import datetime as dt
 import collections
 
-from .parameterized import (
+from .parameterized import ( _Undefined,
     Parameterized, Parameter, String, ParameterizedFunction, ParamOverrides,
     descendents, get_logger, instance_descriptor, basestring)
 
@@ -778,8 +778,8 @@ class Number(Dynamic):
 
     __slots__ = ['bounds', 'softbounds', 'inclusive_bounds', 'set_hook', 'step']
 
-    def __init__(self, default=0.0, bounds=None, softbounds=None,
-                 inclusive_bounds=(True,True), step=None, **params):
+    def __init__(self, default=0.0, bounds=_Undefined, softbounds=_Undefined,
+                 inclusive_bounds=(True,True), step=_Undefined, **params):
         """
         Initialize this parameter object and store the bounds.
 
@@ -792,7 +792,6 @@ def __init__(self, default=0.0, bounds=None, softbounds=None,
         self.inclusive_bounds = inclusive_bounds
         self.softbounds = softbounds
         self.step = step
-        self._validate(default)
 
     def __get__(self, obj, objtype):
         """
@@ -944,7 +943,7 @@ def _validate_step(self, val, step):
 class Magnitude(Number):
     """Numeric Parameter required to be in the range [0.0-1.0]."""
 
-    def __init__(self, default=1.0, softbounds=None, **params):
+    def __init__(self, default=1.0, softbounds=_Undefined, **params):
         Number.__init__(self, default=default, bounds=(0.0,1.0), softbounds=softbounds, **params)
 
 
@@ -977,22 +976,21 @@ class Tuple(Parameter):
 
     __slots__ = ['length']
 
-    def __init__(self, default=(0,0), length=None, **params):
+    def __init__(self, default=(0,0), length=_Undefined, **params):
         """
         Initialize a tuple parameter with a fixed length (number of
         elements).  The length is determined by the initial default
         value, if any, and must be supplied explicitly otherwise.  The
         length is not allowed to change after instantiation.
         """
         super(Tuple,self).__init__(default=default, **params)
-        if length is None and default is not None:
-            self.length = len(default)
-        elif length is None and default is None:
+        if length is _Undefined and self.default is not None:
+            self.length = len(self.default)
+        elif length is _Undefined and self.default is None:
             raise ValueError("%s: length must be specified if no default is supplied." %
                              (self.name))
         else:
             self.length = length
-        self._validate(default)
 
     def _validate_value(self, val, allow_None):
         if val is None and allow_None:
@@ -1114,10 +1112,10 @@ class Composite(Parameter):
 
     __slots__ = ['attribs', 'objtype']
 
-    def __init__(self, attribs=None, **kw):
-        if attribs is None:
+    def __init__(self, attribs=_Undefined, **kw):
+        if attribs is _Undefined:
             attribs = []
-        super(Composite, self).__init__(default=None, **kw)
+        super(Composite, self).__init__(default=_Undefined, **kw)
         self.attribs = attribs
 
     def __get__(self, obj, objtype):
@@ -1192,12 +1190,12 @@ class Selector(SelectorBase):
 
     # Selector is usually used to allow selection from a list of
     # existing objects, therefore instantiate is False by default.
-    def __init__(self, objects=None, default=None, instantiate=False,
-                 compute_default_fn=None, check_on_set=None,
-                 allow_None=None, empty_default=False, **params):
+    def __init__(self, objects=_Undefined, default=_Undefined, instantiate=False,
+                 compute_default_fn=_Undefined, check_on_set=_Undefined,
+                 allow_None=_Undefined, empty_default=False, **params):
 
         autodefault = None
-        if objects:
+        if objects is not _Undefined:
             if is_ordered_dict(objects):
                 autodefault = list(objects.values())[0]
             elif isinstance(objects, dict):
@@ -1209,9 +1207,9 @@ def __init__(self, objects=None, default=None, instantiate=False,
             elif isinstance(objects, list):
                 autodefault = objects[0]
 
-        default = autodefault if (not empty_default and default is None) else default
+        default = autodefault if (not empty_default and default is _Undefined) else default
 
-        if objects is None:
+        if objects is _Undefined:
             objects = []
         if isinstance(objects, collections_abc.Mapping):
             self.names = objects
@@ -1221,7 +1219,7 @@ def __init__(self, objects=None, default=None, instantiate=False,
             self.objects = objects
         self.compute_default_fn = compute_default_fn
 
-        if check_on_set is not None:
+        if check_on_set is not _Undefined:
             self.check_on_set = check_on_set
         elif len(objects) == 0:
             self.check_on_set = False
@@ -1232,8 +1230,6 @@ def __init__(self, objects=None, default=None, instantiate=False,
             default=default, instantiate=instantiate, **params)
         # Required as Parameter sets allow_None=True if default is None
         self.allow_None = allow_None
-        if default is not None and self.check_on_set is True:
-            self._validate(default)
 
     # Note that if the list of objects is changed, the current value for
     # this parameter in existing POs could be outside of the new range.
@@ -1255,6 +1251,10 @@ def _validate(self, val):
         """
         val must be None or one of the objects in self.objects.
         """
+
+        if self.default is None or self.check_on_set is True:
+            return
+
         if not self.check_on_set:
             self._ensure_value_is_in_objects(val)
             return
@@ -1305,7 +1305,7 @@ class ObjectSelector(Selector):
     Deprecated. Same as Selector, but with a different constructor for
     historical reasons.
     """
-    def __init__(self, default=None, objects=None, **kwargs):
+    def __init__(self, default=_Undefined, objects=_Undefined, **kwargs):
         super(ObjectSelector,self).__init__(objects=objects, default=default,
                                             empty_default=True, **kwargs)
 
@@ -1320,11 +1320,10 @@ class ClassSelector(SelectorBase):
 
     __slots__ = ['class_', 'is_instance']
 
-    def __init__(self,class_,default=None,instantiate=True,is_instance=True,**params):
+    def __init__(self, class_, default=_Undefined, instantiate=True, is_instance=True, **params):
         self.class_ = class_
         self.is_instance = is_instance
         super(ClassSelector,self).__init__(default=default,instantiate=instantiate,**params)
-        self._validate(default)
 
     def _validate(self, val):
         super(ClassSelector, self)._validate(val)
@@ -1384,14 +1383,13 @@ class List(Parameter):
 
     __slots__ = ['bounds', 'item_type', 'class_']
 
-    def __init__(self, default=[], class_=None, item_type=None,
+    def __init__(self, default=[], class_=_Undefined, item_type=_Undefined,
                  instantiate=True, bounds=(0, None), **params):
         self.item_type = item_type or class_
         self.class_ = self.item_type
         self.bounds = bounds
         Parameter.__init__(self, default=default, instantiate=instantiate,
                            **params)
-        self._validate(default)
 
     def _validate(self, val):
         """
@@ -1463,7 +1461,7 @@ class Dict(ClassSelector):
     Parameter whose value is a dictionary.
     """
 
-    def __init__(self, default=None, **params):
+    def __init__(self, default=_Undefined, **params):
         super(Dict, self).__init__(dict, default=default, **params)
 
 
@@ -1472,7 +1470,7 @@ class Array(ClassSelector):
     Parameter whose value is a numpy array.
     """
 
-    def __init__(self, default=None, **params):
+    def __init__(self, default=_Undefined, **params):
         from numpy import ndarray
         super(Array, self).__init__(ndarray, allow_None=True, default=default, **params)
 
@@ -1511,13 +1509,12 @@ class DataFrame(ClassSelector):
 
     __slots__ = ['rows', 'columns', 'ordered']
 
-    def __init__(self, default=None, rows=None, columns=None, ordered=None, **params):
+    def __init__(self, default=_Undefined, rows=_Undefined, columns=_Undefined, ordered=_Undefined, **params):
         from pandas import DataFrame as pdDFrame
         self.rows = rows
         self.columns = columns
         self.ordered = ordered
         super(DataFrame,self).__init__(pdDFrame, default=default, **params)
-        self._validate(self.default)
 
     def _length_bounds_check(self, bounds, length, name):
         message = '{name} length {length} does not match declared bounds of {bounds}'
@@ -1588,12 +1585,11 @@ class Series(ClassSelector):
 
     __slots__ = ['rows']
 
-    def __init__(self, default=None, rows=None, allow_None=False, **params):
+    def __init__(self, default=_Undefined, rows=_Undefined, allow_None=False, **params):
         from pandas import Series as pdSeries
         self.rows = rows
         super(Series,self).__init__(pdSeries, default=default, allow_None=allow_None,
                                     **params)
-        self._validate(self.default)
 
     def _length_bounds_check(self, bounds, length, name):
         message = '{name} length {length} does not match declared bounds of {bounds}'
@@ -1731,8 +1727,8 @@ class Path(Parameter):
 
     __slots__ = ['search_paths']
 
-    def __init__(self, default=None, search_paths=None, **params):
-        if search_paths is None:
+    def __init__(self, default=_Undefined, search_paths=_Undefined, **params):
+        if search_paths is _Undefined:
             search_paths = []
 
         self.search_paths = search_paths
@@ -1832,7 +1828,7 @@ class FileSelector(Selector):
     """
     __slots__ = ['path']
 
-    def __init__(self, default=None, path="", **kwargs):
+    def __init__(self, default=_Undefined, path="", **kwargs):
         self.default = default
         self.path = path
         self.update()
@@ -1860,7 +1856,7 @@ class ListSelector(Selector):
     a list of possible objects.
     """
 
-    def __init__(self, default=None, objects=None, **kwargs):
+    def __init__(self, default=_Undefined, objects=_Undefined, **kwargs):
         super(ListSelector,self).__init__(
             objects=objects, default=default, empty_default=True, **kwargs)
 
@@ -1885,7 +1881,7 @@ class MultiFileSelector(ListSelector):
     """
     __slots__ = ['path']
 
-    def __init__(self, default=None, path="", **kwargs):
+    def __init__(self, default=_Undefined, path="", **kwargs):
         self.default = default
         self.path = path
         self.update()
@@ -1911,7 +1907,7 @@ class Date(Number):
     Date parameter of datetime or date type.
     """
 
-    def __init__(self, default=None, **kwargs):
+    def __init__(self, default=_Undefined, **kwargs):
         super(Date, self).__init__(default=default, **kwargs)
 
     def _validate_value(self, val, allow_None):
@@ -1955,7 +1951,7 @@ class CalendarDate(Number):
     Parameter specifically allowing dates (not datetimes).
     """
 
-    def __init__(self, default=None, **kwargs):
+    def __init__(self, default=_Undefined, **kwargs):
         super(CalendarDate, self).__init__(default=default, **kwargs)
 
     def _validate_value(self, val, allow_None):
@@ -2031,10 +2027,9 @@ class Color(Parameter):
 
     __slots__ = ['allow_named']
 
-    def __init__(self, default=None, allow_named=True, **kwargs):
+    def __init__(self, default=_Undefined, allow_named=True, **kwargs):
         super(Color, self).__init__(default=default, **kwargs)
         self.allow_named = allow_named
-        self._validate(default)
 
     def _validate(self, val):
         self._validate_value(val, self.allow_None)
@@ -2067,8 +2062,8 @@ class Range(NumericTuple):
 
     __slots__ = ['bounds', 'inclusive_bounds', 'softbounds', 'step']
 
-    def __init__(self,default=None, bounds=None, softbounds=None,
-                 inclusive_bounds=(True,True), step=None, **params):
+    def __init__(self, default=_Undefined, bounds=_Undefined, softbounds=_Undefined,
+                 inclusive_bounds=(True,True), step=_Undefined, **params):
         self.bounds = bounds
         self.inclusive_bounds = inclusive_bounds
         self.softbounds = softbounds

param/parameterized.py

@@ -969,7 +969,8 @@ class Foo(Bar):
 
     _serializers = {'json': serializer.JSONSerialization}
 
-    def __init__(self,default=None, doc=None, label=None, precedence=None,  # pylint: disable-msg=R0913
+    def __init__(self, default=_Undefined, doc=_Undefined, # pylint: disable-msg=R0913
+                 label=_Undefined, precedence=_Undefined,
                  instantiate=False, constant=False, readonly=False,
                  pickle_default_value=True, allow_None=False,
                  per_instance=True):
@@ -1056,7 +1057,7 @@ class hierarchy (see ParameterizedMetaclass).
         self._internal_name = None
         self._set_instantiate(instantiate)
         self.pickle_default_value = pickle_default_value
-        self.allow_None = (default is None or allow_None)
+        self.allow_None = (self.default is None or allow_None)
         self.watchers = {}
         self.per_instance = per_instance
 
@@ -1317,7 +1318,7 @@ def __init__(self, default="0.0.0.0", allow_None=False, **kwargs):
     def __init__(self, default="", regex=None, allow_None=False, **kwargs):
         super(String, self).__init__(default=default, allow_None=allow_None, **kwargs)
         self.regex = regex
-        self.allow_None = (default is None or allow_None)
+        self.allow_None = (self.default is None or allow_None)
         self._validate(default)
 
     def _validate_regex(self, val, regex):
@@ -1831,6 +1832,10 @@ def add_parameter(self_, param_name, param_obj):
         except AttributeError:
             pass
 
+        if hasattr(param_obj, '_validate'):
+            param_obj._validate(param_obj.default)
+
+
     # PARAM2_DEPRECATION: Backwards compatibilitity for param<1.12
     _add_parameter = add_parameter
 
@@ -2680,6 +2685,13 @@ def __init__(mcs, name, bases, dict_):
         if docstring_signature:
             mcs.__class_docstring_signature()
 
+        # Validation is done here rather than in the Parameter itself so that slot
+        # values can be inherited along superclasses
+        for p in mcs.param.objects().values():
+            if hasattr(p, '_validate'):
+                p._validate(p.default)
+
+
     def __class_docstring_signature(mcs, max_repr_len=15):
         """
         Autogenerate a keyword signature in the class docstring for
@@ -2847,14 +2859,14 @@ def __param_inheritance(mcs,param_name,param):
                 param.instantiate=True
         del slots['instantiate']
 
-
+        supers = classlist(mcs)[::-1]
         for slot in slots.keys():
-            superclasses = iter(classlist(mcs)[::-1])
+            superclasses = iter(supers)
 
             # Search up the hierarchy until param.slot (which has to
             # be obtained using getattr(param,slot)) is not None, or
             # we run out of classes to search.
-            while getattr(param,slot) is None:
+            while getattr(param,slot) is _Undefined:
                 try:
                     param_super_class = next(superclasses)
                 except StopIteration:
@@ -2865,7 +2877,10 @@ def __param_inheritance(mcs,param_name,param):
                     # (slot might not be there because could be a more
                     # general type of Parameter)
                     new_value = getattr(new_param,slot)
-                    setattr(param,slot,new_value)
+                    if new_value is not _Undefined:
+                        setattr(param, slot, new_value)
+            if getattr(param, slot) is _Undefined:
+                setattr(param, slot, None)
 
 
     def get_param_descriptor(mcs,param_name):
@@ -3163,6 +3178,7 @@ def __init__(self, **params):
 
         self.initialized = True
 
+
     @property
     def param(self):
         return Parameters(self.__class__, self=self)