Pretty linked widgets in the IPython notebook

TheWire.ipynb

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   "cells": [
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "# Wire Chase\n",
      "A [fairly decent][mcnulty] way to bind together some IPython widgets for quick prototyping. Made of evil python `__magic__`.\n",
      "\n",
      "<a class=\"btn btn-primary\" href=\"#Example\">Go to example</a>\n",
      "\n",
      ">     Bubbles: What the hell is that? \n",
      ">     McNulty: Baltimore knot. \n",
      ">     Bubbles: Baltimore knot? What the hell is a Baltimore knot?\n",
      ">     McNulty: I dunno, but it's never the same thing twice.\n",
      "> _\u2013 The Wire: Undertow_\n",
      "\n",
      "[mcnulty]: https://31.media.tumblr.com/0e3bb59ff2e32ca57501384e9560876e/tumblr_inline_n0607sPY4K1sohsil.gif"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "from IPython.html import widgets\n",
      "from IPython.utils import traitlets\n",
      "from IPython.display import display"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 67
    },
    {
     "cell_type": "code",
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     "input": [
      "class Chase(object):\n",
      "    \"\"\"\n",
      "    An organizer for Wires.\n",
      "    \"\"\"\n",
      "    def __init__(self, **kwargs):\n",
      "        self.__dict__[\"_widgets\"] = dict([\n",
      "            (name, Wire(widget))\n",
      "            for name, widget in kwargs.items()\n",
      "        ])\n",
      "    \n",
      "    def __call__(self, wired, **kwargs):\n",
      "        \"\"\"\n",
      "        Decorator-style.\n",
      "        \"\"\"\n",
      "        def wrapper(func):\n",
      "            wire, trait = wired\n",
      "            setattr(wire, trait, (kwargs, func))\n",
      "        return wrapper\n",
      "    \n",
      "    def __dir__(self):\n",
      "        return self._widgets.keys()\n",
      "\n",
      "    def __getattr__(self, name):\n",
      "        return self._widgets[name]\n",
      "\n",
      "    def __setattr__(self, name, widget):\n",
      "        self._widgets[name] = Wire(widget)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 57
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "class Wire(object):\n",
      "    \"\"\"\n",
      "    A wrapper for a widget that lets us talk about its traits easily.\n",
      "    \"\"\"\n",
      "    def __init__(self, widget):\n",
      "        self.__dict__[\"_widget\"] = widget\n",
      "        \n",
      "    def __dir__(self):\n",
      "        return self._widget.trait_names()\n",
      "        \n",
      "    def __getattr__(self, name):\n",
      "        return (self, name)\n",
      "    \n",
      "    def __setattr__(self, name, value):\n",
      "        if hasattr(value[-1], '__call__'):\n",
      "            fn = value[-1]\n",
      "            sources = value[:-1]\n",
      "            \n",
      "            if len(sources) == 1 and isinstance(sources[0], dict):\n",
      "                sources = sources[0]\n",
      "                def _change(changed, old, new):\n",
      "                    args = dict([(arg, getattr(t[0]._widget, t[1]))\n",
      "                        for arg, t in sources.items()])\n",
      "                    setattr(self._widget, name, fn(**args))\n",
      "\n",
      "                [t[0]._widget.on_trait_change(_change, t[1])\n",
      "                     for arg, t in sources.items()]\n",
      "            else:\n",
      "                def _change(name, old, new):\n",
      "                    args = [getattr(w._widget, t) for w, t in sources]\n",
      "                    setattr(self._widget, name, fn(*args))\n",
      "\n",
      "                [w._widget.on_trait_change(_change, t) for w, t in sources]\n",
      "        else:\n",
      "            w, t = value\n",
      "            w = w._widget\n",
      "            traitlets.link((self._widget, name), (w, t))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 58
    },
    {
     "cell_type": "heading",
     "level": 1,
     "metadata": {},
     "source": [
      "Example"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "First, we set up some widgets."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "texts = dict([\n",
      "    (i, widgets.TextWidget(description=i, value=i))\n",
      "    for i in \"abcdef\"\n",
      "])\n",
      "wire = Chase(**texts)\n",
      "widgets.ContainerWidget(children=sorted(texts.values()))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 59
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Link with assignment"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Setting one trait pointer to another will make one value equal another, bidirectionally."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "wire.a.value = wire.b.value"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 60
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Now try changing the `a` and `b` boxes."
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## A lambda approaches!\n",
      "If one trait is derived from another trait, give the trait that changes and a transformer. They will be linked, but only forwards."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def but_reversed(b):\n",
      "    return b[::-1]\n",
      "\n",
      "wire.c.value = wire.b.value, but_reversed"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 61
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "This is just a tuple, and any number of traits can be watched."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def joined_and_reversed(a, b):\n",
      "    return a + b[::-1]\n",
      "\n",
      "wire.d.value = wire.a.value, wire.b.value, joined_and_reversed"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 62
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Since this happens kinda often, you can also use a decorator form:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "@wire(wire.e.value, a=wire.a.value)\n",
      "def thrice(a):\n",
      "    return a * 3"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 63
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Secretly, this is using a dictionary instead of a tuple in assignment, or:"
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def joined_differently(a, c):\n",
      "    return c + a\n",
      "wire.f.value = dict(a=wire.a.value, c=wire.c.value), joined_differently"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 64
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "## Autocompleter\n",
      "We proxy through what's connected, so you can autocomplete to see what widgets are wired."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dir(wire)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 65,
       "text": [
        "['a', 'b', 'c', 'd', 'e', 'f']"
       ]
      }
     ],
     "prompt_number": 65
    },
    {
     "cell_type": "markdown",
     "metadata": {},
     "source": [
      "Also the traits on a particular widget."
     ]
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "dir(wire.a)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "metadata": {},
       "output_type": "pyout",
       "prompt_number": 66,
       "text": [
        "['_css',\n",
        " '_display_callbacks',\n",
        " '_model_name',\n",
        " '_msg_callbacks',\n",
        " '_property_lock',\n",
        " '_send_state_lock',\n",
        " '_states_to_send',\n",
        " '_view_name',\n",
        " 'comm',\n",
        " 'config',\n",
        " 'description',\n",
        " 'disabled',\n",
        " 'keys',\n",
        " 'log',\n",
        " 'msg_throttle',\n",
        " 'parent',\n",
        " 'placeholder',\n",
        " 'value',\n",
        " 'visible']"
       ]
      }
     ],
     "prompt_number": 66
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [],
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