Add traitlet for validating number format

ipywidgets/widgets/__init__.py

@@ -5,7 +5,7 @@
 from .domwidget import DOMWidget
 from .valuewidget import ValueWidget
 
-from .trait_types import Color, Datetime
+from .trait_types import Color, Datetime, NumberFormat
 
 from .widget_core import CoreWidget
 from .widget_bool import Checkbox, ToggleButton, Valid

ipywidgets/widgets/tests/test_traits.py

@@ -8,11 +8,26 @@
 from unittest import TestCase
 from traitlets import HasTraits
 from traitlets.tests.test_traitlets import TraitTestBase
-from ipywidgets import Color
+
+from ipywidgets import Color, NumberFormat
 from ipywidgets.widgets.widget import _remove_buffers, _put_buffers
 from ipywidgets.widgets.trait_types import date_serialization
 
 
+class NumberFormatTrait(HasTraits):
+    value = NumberFormat(".3f")
+
+
+class TestNumberFormat(TraitTestBase):
+    obj = NumberFormatTrait()
+
+    _good_values = [
+        '.2f', '.0%', '($.2f', '+20', '.^20', '.2s', '#x', ',.2r',
+        ' .2f', '.2', ''
+    ]
+    _bad_values = [52, False, 'broken', '..2f', '.2a']
+
+
 class ColorTrait(HasTraits):
     value = Color("black")
 

ipywidgets/widgets/tests/test_widget_float.py

@@ -0,0 +1,22 @@
+# Copyright (c) Jupyter Development Team.
+# Distributed under the terms of the Modified BSD License.
+
+from unittest import TestCase
+
+from traitlets import TraitError
+
+from ipywidgets import FloatSlider
+
+
+class TestFloatSlider(TestCase):
+
+    def test_construction(self):
+        FloatSlider()
+
+    def test_construction_readout_format(self):
+        slider = FloatSlider(readout_format='$.1f')
+        assert slider.get_state()['readout_format'] == '$.1f'
+
+    def test_construction_invalid_readout_format(self):
+        with self.assertRaises(TraitError):
+            FloatSlider(readout_format='broken')

ipywidgets/widgets/trait_types.py

@@ -9,7 +9,8 @@
 import traitlets
 import datetime as dt
 
-_color_names = ['aliceblue', 'antiquewhite', 'aqua', 'aquamarine', 'azure', 'beige', 'bisque', 'black', 'blanchedalmond', 'blue', 'blueviolet', 'brown', 'burlywood', 'cadetblue', 'chartreuse', 'chocolate', 'coral', 'cornflowerblue', 'cornsilk', 'crimson', 'cyan', 'darkblue', 'darkcyan', 'darkgoldenrod', 'darkgray', 'darkgreen', 'darkkhaki', 'darkmagenta', 'darkolivegreen', 'darkorange', 'darkorchid', 'darkred', 'darksalmon', 'darkseagreen', 'darkslateblue', 'darkslategray', 'darkturquoise', 'darkviolet', 'deeppink', 'deepskyblue', 'dimgray', 'dodgerblue', 'firebrick', 'floralwhite', 'forestgreen', 'fuchsia', 'gainsboro', 'ghostwhite', 'gold', 'goldenrod', 'gray', 'green', 'greenyellow', 'honeydew', 'hotpink', 'indianred ', 'indigo ', 'ivory', 'khaki', 'lavender', 'lavenderblush', 'lawngreen', 'lemonchiffon', 'lightblue', 'lightcoral', 'lightcyan', 'lightgoldenrodyellow', 'lightgray', 'lightgreen', 'lightpink', 'lightsalmon', 'lightseagreen', 'lightskyblue', 'lightslategray', 'lightsteelblue', 'lightyellow', 'lime', 'limegreen', 'linen', 'magenta', 'maroon', 'mediumaquamarine', 'mediumblue', 'mediumorchid', 'mediumpurple', 'mediumseagreen', 'mediumslateblue', 'mediumspringgreen', 'mediumturquoise', 'mediumvioletred', 'midnightblue', 'mintcream', 'mistyrose', 'moccasin', 'navajowhite', 'navy', 'oldlace', 'olive', 'olivedrab', 'orange', 'orangered', 'orchid', 'palegoldenrod', 'palegreen', 'paleturquoise', 'palevioletred', 'papayawhip', 'peachpuff', 'peru', 'pink', 'plum', 'powderblue', 'purple', 'rebeccapurple', 'red', 'rosybrown', 'royalblue', 'saddlebrown', 'salmon', 'sandybrown', 'seagreen', 'seashell', 'sienna', 'silver', 'skyblue', 'slateblue', 'slategray', 'snow', 'springgreen', 'steelblue', 'tan', 'teal', 'thistle', 'tomato', 'turquoise', 'violet', 'wheat', 'white', 'whitesmoke', 'yellow', 'yellowgreen'] 
+
+_color_names = ['aliceblue', 'antiquewhite', 'aqua', 'aquamarine', 'azure', 'beige', 'bisque', 'black', 'blanchedalmond', 'blue', 'blueviolet', 'brown', 'burlywood', 'cadetblue', 'chartreuse', 'chocolate', 'coral', 'cornflowerblue', 'cornsilk', 'crimson', 'cyan', 'darkblue', 'darkcyan', 'darkgoldenrod', 'darkgray', 'darkgreen', 'darkkhaki', 'darkmagenta', 'darkolivegreen', 'darkorange', 'darkorchid', 'darkred', 'darksalmon', 'darkseagreen', 'darkslateblue', 'darkslategray', 'darkturquoise', 'darkviolet', 'deeppink', 'deepskyblue', 'dimgray', 'dodgerblue', 'firebrick', 'floralwhite', 'forestgreen', 'fuchsia', 'gainsboro', 'ghostwhite', 'gold', 'goldenrod', 'gray', 'green', 'greenyellow', 'honeydew', 'hotpink', 'indianred ', 'indigo ', 'ivory', 'khaki', 'lavender', 'lavenderblush', 'lawngreen', 'lemonchiffon', 'lightblue', 'lightcoral', 'lightcyan', 'lightgoldenrodyellow', 'lightgray', 'lightgreen', 'lightpink', 'lightsalmon', 'lightseagreen', 'lightskyblue', 'lightslategray', 'lightsteelblue', 'lightyellow', 'lime', 'limegreen', 'linen', 'magenta', 'maroon', 'mediumaquamarine', 'mediumblue', 'mediumorchid', 'mediumpurple', 'mediumseagreen', 'mediumslateblue', 'mediumspringgreen', 'mediumturquoise', 'mediumvioletred', 'midnightblue', 'mintcream', 'mistyrose', 'moccasin', 'navajowhite', 'navy', 'oldlace', 'olive', 'olivedrab', 'orange', 'orangered', 'orchid', 'palegoldenrod', 'palegreen', 'paleturquoise', 'palevioletred', 'papayawhip', 'peachpuff', 'peru', 'pink', 'plum', 'powderblue', 'purple', 'rebeccapurple', 'red', 'rosybrown', 'royalblue', 'saddlebrown', 'salmon', 'sandybrown', 'seagreen', 'seashell', 'sienna', 'silver', 'skyblue', 'slateblue', 'slategray', 'snow', 'springgreen', 'steelblue', 'tan', 'teal', 'thistle', 'tomato', 'turquoise', 'violet', 'wheat', 'white', 'whitesmoke', 'yellow', 'yellowgreen']
 _color_re = re.compile(r'#[a-fA-F0-9]{3}(?:[a-fA-F0-9]{3})?$')
 
 
@@ -61,8 +62,8 @@ def datetime_to_json(pydt, manager):
             year=pydt.year,
             month=pydt.month - 1,  # Months are 0-based indices in JS
             date=pydt.day,
-            hours=pydt.hour,       # Hours, Minutes, Seconds and Milliseconds are
-            minutes=pydt.minute,   # plural in JS
+            hours=pydt.hour,       # Hours, Minutes, Seconds and Milliseconds
+            minutes=pydt.minute,   # are plural in JS
             seconds=pydt.second,
             milliseconds=pydt.microsecond / 1000
         )
@@ -88,6 +89,7 @@ def datetime_from_json(js, manager):
     'to_json': datetime_to_json
 }
 
+
 def date_to_json(pydate, manager):
     """Serialize a Python date object.
 
@@ -123,10 +125,12 @@ def date_from_json(js, manager):
 
 class InstanceDict(traitlets.Instance):
     """An instance trait which coerces a dict to an instance.
-
-    This lets the instance be specified as a dict, which is used to initialize the instance.
-
-    Also, we default to a trivial instance, even if args and kwargs is not specified."""
+
+    This lets the instance be specified as a dict, which is used
+    to initialize the instance.
+
+    Also, we default to a trivial instance, even if args and kwargs
+    is not specified."""
 
     def validate(self, obj, value):
         if isinstance(value, dict):
@@ -137,3 +141,45 @@ def validate(self, obj, value):
     def make_dynamic_default(self):
         return self.klass(*(self.default_args or ()),
                           **(self.default_kwargs or {}))
+
+
+# The regexp is taken
+# from https://github.com/d3/d3-format/blob/master/src/formatSpecifier.js
+_number_format_re = re.compile('^(?:(.)?([<>=^]))?([+\-\( ])?([$#])?(0)?(\d+)?(,)?(\.\d+)?([a-z%])?$', re.I)
+
+# The valid types are taken from
+# https://github.com/d3/d3-format/blob/master/src/formatTypes.js
+_number_format_types = {
+    'e', 'f', 'g', 'r', 's', '%', 'p', 'b', 'o', 'd', 'x',
+    'X', 'c', ''
+}
+
+
+class NumberFormat(traitlets.Unicode):
+    """A string holding a number format specifier, e.g. '.3f'
+
+    This traitlet holds a string that can be passed to the
+    `d3-format <https://github.com/d3/d3-format>`_ JavaScript library.
+    The format allowed is similar to the Python format specifier (PEP 3101).
+    """
+    info_text = 'a valid number format'
+    default_value = traitlets.Undefined
+
+    def validate(self, obj, value):
+        value = super(NumberFormat, self).validate(obj, value)
+        re_match = _number_format_re.match(value)
+        if re_match is None:
+            self.error(obj, value)
+        else:
+            format_type = re_match.group(9)
+            if format_type is None:
+                return value
+            elif format_type in _number_format_types:
+                return value
+            else:
+                raise traitlets.TraitError(
+                    'The type specifier of a NumberFormat trait must '
+                    'be one of {}, but a value of \'{}\' was '
+                    'specified.'.format(
+                        list(_number_format_types), format_type)
+                )

ipywidgets/widgets/widget_float.py

@@ -10,7 +10,7 @@
     Instance, Unicode, CFloat, Bool, CaselessStrEnum, Tuple, TraitError, validate, default
 )
 from .widget_description import DescriptionWidget
-from .trait_types import InstanceDict
+from .trait_types import InstanceDict, NumberFormat
 from .valuewidget import ValueWidget
 from .widget import register, widget_serialization
 from .widget_core import CoreWidget
@@ -129,7 +129,8 @@ class FloatSlider(_BoundedFloat):
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
-    readout_format = Unicode('.2f', help="Format for the readout").tag(sync=True)
+    readout_format = NumberFormat(
+        '.2f', help="Format for the readout").tag(sync=True)
     continuous_update = Bool(True, help="Update the value of the widget as the user is holding the slider.").tag(sync=True)
     disabled = Bool(False, help="Enable or disable user changes").tag(sync=True)
 
@@ -265,7 +266,8 @@ class FloatRangeSlider(_BoundedFloatRange):
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
-    readout_format = Unicode('.2f', help="Format for the readout").tag(sync=True)
+    readout_format = NumberFormat(
+        '.2f', help="Format for the readout").tag(sync=True)
     continuous_update = Bool(True, help="Update the value of the widget as the user is sliding the slider.").tag(sync=True)
     disabled = Bool(False, help="Enable or disable user changes").tag(sync=True)
 

ipywidgets/widgets/widget_int.py

@@ -11,7 +11,7 @@
 from .widget import register, widget_serialization
 from .widget_core import CoreWidget
 from traitlets import Instance
-from .trait_types import Color, InstanceDict
+from .trait_types import Color, InstanceDict, NumberFormat
 from traitlets import (
     Unicode, CInt, Bool, CaselessStrEnum, Tuple, TraitError, default, validate
 )
@@ -157,7 +157,8 @@ class IntSlider(_BoundedInt):
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
-    readout_format = Unicode('d', help="Format for the readout").tag(sync=True)
+    readout_format = NumberFormat(
+        'd', help="Format for the readout").tag(sync=True)
     continuous_update = Bool(True, help="Update the value of the widget as the user is holding the slider.").tag(sync=True)
     disabled = Bool(False, help="Enable or disable user changes").tag(sync=True)
 
@@ -282,7 +283,8 @@ class IntRangeSlider(_BoundedIntRange):
     orientation = CaselessStrEnum(values=['horizontal', 'vertical'],
         default_value='horizontal', help="Vertical or horizontal.").tag(sync=True)
     readout = Bool(True, help="Display the current value of the slider next to it.").tag(sync=True)
-    readout_format = Unicode('d', help="Format for the readout").tag(sync=True)
+    readout_format = NumberFormat(
+        'd', help="Format for the readout").tag(sync=True)
     continuous_update = Bool(True, help="Update the value of the widget as the user is sliding the slider.").tag(sync=True)
     style = InstanceDict(SliderStyle, help="Slider style customizations.").tag(sync=True, **widget_serialization)
     disabled = Bool(False, help="Enable or disable user changes").tag(sync=True)