Add pytypes property to parameters to return Python type declaration

Author: philippjfr

param/__init__.py

@@ -24,6 +24,8 @@
 import re
 import datetime as dt
 import collections
+import numbers
+import typing
 
 from .parameterized import (
     Parameterized, Parameter, String, ParameterizedFunction, ParamOverrides,
@@ -692,7 +694,6 @@ def _force(self,obj,objtype=None):
             return gen
 
 
-import numbers
 def _is_number(obj):
     if isinstance(obj, numbers.Number): return True
     # The extra check is for classes that behave like numbers, such as those
@@ -752,6 +753,10 @@ def __init__(self, default=b"", regex=None, allow_None=False, **kwargs):
         self.allow_None = (default is None or allow_None)
         self._validate(default)
 
+    @property
+    def pytype(self):
+        return typing.Union[bytes, None] if self.allow_None else bytes
+
     def _validate_regex(self, val, regex):
         if (val is None and self.allow_None):
             return
@@ -834,6 +839,10 @@ def __init__(self, default=0.0, bounds=None, softbounds=None,
         self.step = step
         self._validate(default)
 
+    @property
+    def pytype(self):
+        return typing.Union[numbers.Number, None] if self.allow_None else numbers.Number
+
     def __get__(self, obj, objtype):
         """
         Same as the superclass's __get__, but if the value was
@@ -963,6 +972,10 @@ class Integer(Number):
     def __init__(self, default=0, **params):
         Number.__init__(self, default=default, **params)
 
+    @property
+    def pytype(self):
+        return typing.Union[int, None] if self.allow_None else int
+
     def _validate_value(self, val, allow_None):
         if callable(val):
             return
@@ -1000,6 +1013,10 @@ def __init__(self, default=False, bounds=(0,1), **params):
         self.bounds = bounds
         super(Boolean, self).__init__(default=default, **params)
 
+    @property
+    def pytype(self):
+        return typing.Union[bool, None] if self.allow_None else bool
+
     def _validate_value(self, val, allow_None):
         if allow_None:
             if not isinstance(val, bool) and val is not None:
@@ -1034,6 +1051,14 @@ def __init__(self, default=(0,0), length=None, **params):
             self.length = length
         self._validate(default)
 
+    @property
+    def pytype(self):
+        if self.length:
+            pytype = typing.Tuple[(typing.Any,)*self.length]
+        else:
+            ptype = typing.Tuple[typing.Any, ...]
+        return typing.Union[pytype, None] if self.allow_None else pytype
+
     def _validate_value(self, val, allow_None):
         if val is None and allow_None:
             return
@@ -1071,6 +1096,14 @@ def deserialize(cls, value):
 class NumericTuple(Tuple):
     """A numeric tuple Parameter (e.g. (4.5,7.6,3)) with a fixed tuple length."""
 
+    @property
+    def pytype(self):
+        if self.length:
+            pytype = typing.Tuple[(numbers.Number,)*self.length]
+        else:
+            ptype = typing.Tuple[numbers.Number, ...]
+        return typing.Union[pytype, None] if self.allow_None else pytype
+
     def _validate_value(self, val, allow_None):
         super(NumericTuple, self)._validate_value(val, allow_None)
         if allow_None and val is None:
@@ -1088,6 +1121,11 @@ class XYCoordinates(NumericTuple):
     def __init__(self, default=(0.0, 0.0), **params):
         super(XYCoordinates,self).__init__(default=default, length=2, **params)
 
+    @property
+    def pytype(self):
+        pytype = typing.Tuple[numbers.Number, numbers.Number]
+        return typing.Union[pytype, None] if self.allow_None else pytype
+
 
 class Callable(Parameter):
     """
@@ -1099,6 +1137,11 @@ class Callable(Parameter):
     2.4, so instantiate must be False for those values.
     """
 
+    @proprty
+    def pytype(self):
+        ctype = typing.Callable[..., typing.Any]
+        return typing.Union[ctype, None] if self.allow_None else ctype 
+
     def _validate_value(self, val, allow_None):
         if (allow_None and val is None) or callable(val):
             return
@@ -1197,6 +1240,11 @@ class SelectorBase(Parameter):
 
     __abstract = True
 
+    @proprty
+    def pytype(self):
+        literal = typing.Literal[tuple(self.get_range().values())]
+        return typing.Union[literal, None] if self.allow_None else literal 
+
     def get_range(self):
         raise NotImplementedError("get_range() must be implemented in subclasses.")
 
@@ -1433,6 +1481,17 @@ def __init__(self, default=[], class_=None, item_type=None,
                            **params)
         self._validate(default)
 
+    @property
+    def pytype(self):
+        if isinstance(self.item_type, tuple):
+            item_type = typing.Union[self.item_type]
+        elif self.item_type is not None:
+            item_type = self.item_type
+        else:
+            item_type = typing.Any
+        list_type = typing.List[item_type]
+        return typing.Union[list_type, None] if self.allow_None else list_type
+
     def _validate(self, val):
         """
         Checks that the value is numeric and that it is within the hard
@@ -1487,6 +1546,11 @@ class HookList(List):
     """
     __slots__ = ['class_', 'bounds']
 
+    @property
+    def pytype(self):
+        list_type = typing.List[typing.Callable[[], None]]
+        return typing.Union[list_type, None] if self.allow_None else list_type
+
     def _validate_value(self, val, allow_None):
         super(HookList, self)._validate_value(val, allow_None)
         if allow_None and val is None:
@@ -1506,16 +1570,27 @@ class Dict(ClassSelector):
     def __init__(self, default=None, **params):
         super(Dict, self).__init__(dict, default=default, **params)
 
+    @property
+    def pytype(self):
+        dict_type = typing.Dict[typing.Hashable, typing.Any]
+        return typing.Union[dict_type, None] if self.allow_None else dict_type
+
+
 
 class Array(ClassSelector):
     """
     Parameter whose value is a numpy array.
     """
 
     def __init__(self, default=None, **params):
-        from numpy import ndarray
+        
         super(Array, self).__init__(ndarray, allow_None=True, default=default, **params)
 
+    @property
+    def pytype(self):
+        from numpy import ndarray
+        return ndarray
+
     @classmethod
     def serialize(cls, value):
         if value is None:
@@ -1559,6 +1634,11 @@ def __init__(self, default=None, rows=None, columns=None, ordered=None, **params
         super(DataFrame,self).__init__(pdDFrame, default=default, **params)
         self._validate(self.default)
 
+    @property
+    def pytype(self):
+        from pandas import DataFrame
+        return DataFrame
+
     def _length_bounds_check(self, bounds, length, name):
         message = '{name} length {length} does not match declared bounds of {bounds}'
         if not isinstance(bounds, tuple):
@@ -1635,6 +1715,11 @@ def __init__(self, default=None, rows=None, allow_None=False, **params):
                                     **params)
         self._validate(self.default)
 
+    @property
+    def pytype(self):
+        from pandas import Series
+        return Series
+
     def _length_bounds_check(self, bounds, length, name):
         message = '{name} length {length} does not match declared bounds of {bounds}'
         if not isinstance(bounds, tuple):
@@ -1778,6 +1863,13 @@ def __init__(self, default=None, search_paths=None, **params):
         self.search_paths = search_paths
         super(Path,self).__init__(default,**params)
 
+    @property
+    def pytype(self):
+        path_types  =(str, pathlib.Path)
+        if self.allow_None:
+            path_types += (None,)
+        return typing.Union[path_types]
+
     def _resolve(self, path):
         return resolve_path(path, path_to_file=None, search_paths=self.search_paths)
 
@@ -1904,6 +1996,12 @@ def __init__(self, default=None, objects=None, **kwargs):
         super(ListSelector,self).__init__(
             objects=objects, default=default, empty_default=True, **kwargs)
 
+    @property
+    def pytype(self):
+        literal = typing.Literal[tuple(self.get_range().values())]
+        ltype = typing.List[literal]
+        return typing.Union[ltype, None] if self.allow_None else ltype
+
     def compute_default(self):
         if self.default is None and callable(self.compute_default_fn):
             self.default = self.compute_default_fn()
@@ -1954,6 +2052,14 @@ class Date(Number):
     def __init__(self, default=None, **kwargs):
         super(Date, self).__init__(default=default, **kwargs)
 
+    @property
+    def pytype(self):
+        if self.allow_None:
+            date_types = dt_types + (None,)
+        else:
+            date_types = dt_types
+        return typing.Union[date_types]
+
     def _validate_value(self, val, allow_None):
         """
         Checks that the value is numeric and that it is within the hard
@@ -1998,6 +2104,10 @@ class CalendarDate(Number):
     def __init__(self, default=None, **kwargs):
         super(CalendarDate, self).__init__(default=default, **kwargs)
 
+    @property
+    def pytype(self):
+        return typing.Union[dt.datetime, None] if self.allow_None else dt.datetime
+
     def _validate_value(self, val, allow_None):
         """
         Checks that the value is numeric and that it is within the hard
@@ -2076,6 +2186,10 @@ def __init__(self, default=None, allow_named=True, **kwargs):
         self.allow_named = allow_named
         self._validate(default)
 
+    @property
+    def pytype(self):
+        return typing.Union[str, None] if self.allow_None else str
+
     def _validate(self, val):
         self._validate_value(val, self.allow_None)
         self._validate_allow_named(val, self.allow_named)
@@ -2151,6 +2265,12 @@ class DateRange(Range):
     Bounds must be specified as datetime or date types (see param.dt_types).
     """
 
+    @property
+    def pytype(self):
+        date_type = typing.Union[dt_types]
+        range_type = typing.Tuple[date_type, date_type]
+        return typing.Union[range_type, None] if self.allow_None else range_type
+
     def _validate_value(self, val, allow_None):
         # Cannot use super()._validate_value as DateRange inherits from
         # NumericTuple which check that the tuple values are numbers and
@@ -2205,6 +2325,7 @@ def deserialize(cls, value):
         # As JSON has no tuple representation
         return tuple(deserialized)
 
+
 class CalendarDateRange(Range):
     """
     A date range specified as (start_date, end_date).
@@ -2281,6 +2402,10 @@ def __init__(self,default=False,bounds=(0,1),**params):
         # back to False while triggered callbacks are executing
         super(Event, self).__init__(default=default,**params)
 
+    @property
+    def pytype(self):
+        return bool
+
     def _reset_event(self, obj, val):
         val = False
         if obj is None:

param/parameterized.py

@@ -16,6 +16,7 @@
 import random
 import numbers
 import operator
+import typing
 
 # Allow this file to be used standalone if desired, albeit without JSON serialization
 try:
@@ -1071,6 +1072,10 @@ class hierarchy (see ParameterizedMetaclass).
         self.watchers = {}
         self.per_instance = per_instance
 
+    @property
+    def pytype(self):
+        return typing.Any
+
     @classmethod
     def serialize(cls, value):
         "Given the parameter value, return a Python value suitable for serialization"
@@ -1331,6 +1336,10 @@ def __init__(self, default="", regex=None, allow_None=False, **kwargs):
         self.allow_None = (default is None or allow_None)
         self._validate(default)
 
+    @property
+    def pytype(self):
+        return typing.Union[str, None] if self.allow_None else str
+
     def _validate_regex(self, val, regex):
         if (val is None and self.allow_None):
             return