Panel integer input widget with bounds

panel_boundedintinput.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Panel integer input widget with bounds\n",
    "\n",
    "Works with Panel 0.3.1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
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       "BoundedIntInput(end=10, start=1, type=<class 'int'>, value=0)"
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   "source": [
    "import ast\n",
    "\n",
    "import param\n",
    "from panel import widgets\n",
    "from panel.util import as_unicode\n",
    "    \n",
    "class IntInput(widgets.LiteralInput):\n",
    "\n",
    "    type = int\n",
    "    value = param.Integer(default=None)\n",
    "    _widget_type = widgets._BkTextInput\n",
    "    \n",
    "    def _validate(self, event):\n",
    "        if self.type is None: return\n",
    "        new = self.value\n",
    "        if new is not None and not isinstance(new, self.type):\n",
    "            if event:\n",
    "                self.value = event.old\n",
    "            raise ValueError('IntInput expected %s type but value %s '\n",
    "                             'is of type %s.' %\n",
    "                             (self.type.__name__, new, type(new).__name__))\n",
    "    \n",
    "    def _process_property_change(self, msg):\n",
    "        msg = super(widgets.LiteralInput, self)._process_property_change(msg)\n",
    "        new_state = ''\n",
    "        if 'value' in msg:\n",
    "            value = msg.pop('value')\n",
    "            try:\n",
    "                value = ast.literal_eval(value)\n",
    "            except:\n",
    "                new_state = ' (invalid)'\n",
    "                value = self.value\n",
    "            else:\n",
    "                if self.type and not isinstance(value, self.type):\n",
    "                    new_state = ' (wrong type)'\n",
    "                    value = self.value\n",
    "            msg['value'] = value\n",
    "        msg['name'] = msg.get('title', self.name).replace(self._state, '') + new_state\n",
    "        self._state = new_state\n",
    "        self.param.trigger('name')\n",
    "        return msg\n",
    "\n",
    "    def _process_param_change(self, msg):\n",
    "        msg = super(widgets.LiteralInput, self)._process_param_change(msg)\n",
    "        msg.pop('type', None)\n",
    "        if 'value' in msg:\n",
    "            msg['value'] = '' if msg['value'] is None else as_unicode(msg['value'])\n",
    "        msg['title'] = self.name\n",
    "        return msg\n",
    "    \n",
    "class BoundedIntInput(IntInput):\n",
    "    \n",
    "    start = param.Integer(default=None)\n",
    "    end = param.Integer(default=None)\n",
    "    \n",
    "    def _validate(self, event):\n",
    "        if self.type is None: return\n",
    "        new = self.value\n",
    "        if new is not None and not isinstance(new, self.type):\n",
    "            if event:\n",
    "                self.value = event.old\n",
    "            raise ValueError('BoundedIntInput expected %s type but value %s '\n",
    "                             'is of type %s.' %\n",
    "                             (self.type.__name__, new, type(new).__name__))\n",
    "            \n",
    "    def _process_property_change(self, msg):\n",
    "        msg = super(widgets.LiteralInput, self)._process_property_change(msg)\n",
    "        new_state = ''\n",
    "        if 'value' in msg:\n",
    "            value = msg.pop('value')\n",
    "            try:\n",
    "                value = ast.literal_eval(value)\n",
    "            except:\n",
    "                new_state = ' (invalid)'\n",
    "                value = self.value\n",
    "            else:\n",
    "                print('value: ', value)\n",
    "                if self.type:\n",
    "                    if not isinstance(value, self.type):\n",
    "                        new_state = ' (wrong type)'\n",
    "                        value = self.value\n",
    "                    elif (self.start is not None and value < self.start) or \\\n",
    "                        (self.end is not None and value >= self.end):\n",
    "                        new_state = ' (out of bounds)'\n",
    "                        value = self.value\n",
    "            msg['value'] = value\n",
    "        msg['name'] = msg.get('title', self.name).replace(self._state, '') + new_state\n",
    "        self._state = new_state\n",
    "        self.param.trigger('name')\n",
    "        return msg\n",
    "\n",
    "    def _process_param_change(self, msg):\n",
    "        msg = super(widgets.LiteralInput, self)._process_param_change(msg)\n",
    "        msg.pop('type', None)\n",
    "        msg.pop('start', None)\n",
    "        msg.pop('end', None)\n",
    "        if 'value' in msg:\n",
    "            msg['value'] = '' if msg['value'] is None else as_unicode(msg['value'])\n",
    "        msg['title'] = self.name\n",
    "        return msg\n",
    "    \n",
    "w = BoundedIntInput(start=1, end=10, value=0)\n",
    "w"
   ]
  }
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