Add MultiChoice widget

examples/reference/widgets/MultiChoice.ipynb

@@ -0,0 +1,127 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "import panel as pn\n",
+    "pn.extension()"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The ``MultiChoice`` widget allows selecting multiple values from a list of options. It falls into the broad category of multi-value, option-selection widgets that provide a compatible API and include the [``MultiSelect``](MultiSelect.ipynb), [``CrossSelector``](CrossSelector.ipynb), [``CheckBoxGroup``](CheckBoxGroup.ipynb) and [``CheckButtonGroup``](CheckButtonGroup.ipynb) widgets. The ``MultiChoice`` widget provides a much more compact UI than [``MultiSelect``](MultiSelect.ipynb).\n",
+    "\n",
+    "For more information about listening to widget events and laying out widgets refer to the [widgets user guide](../../user_guide/Widgets.ipynb). Alternatively you can learn how to build GUIs by declaring parameters independently of any specific widgets in the [param user guide](../../user_guide/Param.ipynb). To express interactivity entirely using Javascript without the need for a Python server take a look at the [links user guide](../../user_guide/Param.ipynb).\n",
+    "\n",
+    "#### Parameters:\n",
+    "\n",
+    "For layout and styling related parameters see the [customization user guide](../../user_guide/Customization.ipynb).\n",
+    "\n",
+    "##### Core\n",
+    "\n",
+    "* **``options``** (list or dict): List or dictionary of options\n",
+    "* **``max_items``** (int): Maximum number of options that can be selected\n",
+    "* **``value``** (list): Currently selected option values\n",
+    "\n",
+    "##### Display\n",
+    "\n",
+    "* **``delete_button``** (boolean): Whether to display a button to delete a selected option\n",
+    "* **``disabled``** (boolean): Whether the widget is editable\n",
+    "* **``name``** (str): The title of the widget\n",
+    "* **``option_limit``** (int): Maximum number of options to display at once.\n",
+    "* **``placeholder``** (str): String displayed when no selection has been made.\n",
+    "* **``solid``** (boolean): Whether to display widget with solid or light style.\n",
+    "\n",
+    "___"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "multi_choice = pn.widgets.MultiChoice(name='MultiSelect', value=['Apple', 'Pear'],\n",
+    "    options=['Apple', 'Banana', 'Pear', 'Strawberry'])\n",
+    "\n",
+    "pn.Column(multi_choice, height=200)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "``MultiChoice.value`` returns a list of the currently selected options:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "multi_choice.value"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "The `solid` option controls the style of the widget:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "pn.Column(multi_choice.clone(solid=False), height=200)"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "### Controls\n",
+    "\n",
+    "The `MultiChoice` widget exposes a number of options which can be changed from both Python and Javascript. Try out the effect of these parameters interactively:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "pn.Row(multi_choice.controls(jslink=True), multi_choice)"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "Python 3",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.7.5"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}

panel/tests/widgets/test_select.py

@@ -5,7 +5,9 @@
 import numpy as np
 import pytest
 
-from panel.widgets import Select, MultiSelect, CrossSelector, ToggleGroup
+from panel.widgets import (
+    CrossSelector, MultiChoice, MultiSelect, Select, ToggleGroup
+)
 from panel.util import as_unicode
 
 
@@ -153,6 +155,29 @@ def test_multi_select(document, comm):
     assert widget.value == ['C', 'A']
 
 
+def test_multi_choice(document, comm):
+    choice = MultiChoice(options=OrderedDict([('A', 'A'), ('1', 1), ('C', object)]),
+                         value=[object, 1], name='MultiChoice')
+
+    widget = choice.get_root(document, comm=comm)
+
+    assert isinstance(widget, choice._widget_type)
+    assert widget.title == 'MultiChoice'
+    assert widget.value == ['C', '1']
+    assert widget.options == ['A', '1', 'C']
+
+    widget.value = ['1']
+    choice._comm_change({'value': ['1']})
+    assert choice.value == [1]
+
+    widget.value = ['A', 'C']
+    choice._comm_change({'value': ['A', 'C']})
+    assert choice.value == ['A', object]
+
+    choice.value = [object, 'A']
+    assert widget.value == ['C', 'A']
+
+
 def test_multi_select_change_options(document, comm):
     select = MultiSelect(options=OrderedDict([('A', 'A'), ('1', 1), ('C', object)]),
                          value=[object, 1], name='Select')

panel/widgets/__init__.py

@@ -21,6 +21,7 @@
 )
 from .select import (# noqa
     AutocompleteInput, CheckBoxGroup, CheckButtonGroup, CrossSelector,
-    MultiSelect, RadioButtonGroup, RadioBoxGroup, Select, ToggleGroup
+    MultiChoice, MultiSelect, RadioButtonGroup, RadioBoxGroup, Select,
+    ToggleGroup
 )
 from .tables import DataFrame # noqa

panel/widgets/select.py

@@ -14,7 +14,7 @@
     AutocompleteInput as _BkAutocompleteInput, CheckboxGroup as _BkCheckboxGroup,
     CheckboxButtonGroup as _BkCheckboxButtonGroup, MultiSelect as _BkMultiSelect,
     RadioButtonGroup as _BkRadioButtonGroup, RadioGroup as _BkRadioBoxGroup,
-    Select as _BkSelect)
+    Select as _BkSelect, MultiChoice as _BkMultiChoice)
 
 from ..layout import Column, VSpacer
 from ..util import as_unicode, isIn, indexOf
@@ -115,16 +115,10 @@ def _get_embed_state(self, root, max_opts=3):
                 lambda x: x.value, 'value', 'cb_obj.value')
 
 
-class MultiSelect(Select):
-
-    size = param.Integer(default=4, doc="""
-        The number of items displayed at once (i.e. determines the
-        widget height).""")
+class _MultiSelectBase(Select):
 
     value = param.List(default=[])
 
-    _widget_type = _BkMultiSelect
-
     _supports_embed = False
 
     def _process_param_change(self, msg):
@@ -150,6 +144,34 @@ def _process_property_change(self, msg):
         return msg
 
 
+class MultiSelect(_MultiSelectBase):
+
+    size = param.Integer(default=4, doc="""
+        The number of items displayed at once (i.e. determines the
+        widget height).""")
+
+    _widget_type = _BkMultiSelect
+
+
+class MultiChoice(_MultiSelectBase):
+
+    delete_button = param.Boolean(default=True, doc="""
+        Whether to display a button to delete a selected option.""")
+
+    max_items = param.Integer(default=None, bounds=(1, None), doc="""
+        Maximum number of options that can be selected.""")
+
+    option_limit = param.Integer(default=None, bounds=(1, None), doc="""
+        Maximum number of options to display at once.""")
+
+    placeholder = param.String(default='', doc="""
+        String displayed when no selection has been made.""")
+
+    solid = param.Boolean(default=True, doc="""
+        Whether to display widget with solid or light style.""")
+
+    _widget_type = _BkMultiChoice
+
 
 class AutocompleteInput(Widget):
 
@@ -168,7 +190,6 @@ class AutocompleteInput(Widget):
     _rename = {'name': 'title', 'options': 'completions'}
 
 
-
 class _RadioGroupBase(Select):
 
     _supports_embed = False