{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# First look at pluggy"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "    import pluggy, pytest"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "    import pluggy, pytest"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "    specification, implementation = pluggy.HookspecMarker('example') ,pluggy.HookimplMarker('example')"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "    specification, implementation = pluggy.HookspecMarker('example') ,pluggy.HookimplMarker('example')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "    class Spec:\n",
       "        \n",
       "Define specifications as function with the name of the hook and reusable function signature.\n",
       "        \n",
       "        @specification\n",
       "        def function(object):\n",
       "        \n",
       "A specification needs to exist before an implementation."
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "    class Spec:\n",
    "        \n",
    "Define specifications as function with the name of the hook and reusable function signature.\n",
    "        \n",
    "        @specification\n",
    "        def function(object):\n",
    "        \n",
    "A specification needs to exist before an implementation."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "    @implementation\n",
       "    def function(object):\n",
       "        \n",
       "An implementation of the function specification.\n",
       "        \n",
       "        return type(object)"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "    @implementation\n",
    "    def function(object):\n",
    "        \n",
    "An implementation of the function specification.\n",
    "        \n",
    "        return type(object)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "    class Another:\n",
       "        @implementation(trylast=True)\n",
       "        def function(object):\n",
       "            \n",
       "Another implementation of the function spec.\n",
       "            \n",
       "            return str(object)"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "    class Another:\n",
    "        @implementation(trylast=True)\n",
    "        def function(object):\n",
    "            \n",
    "Another implementation of the function spec.\n",
    "            \n",
    "            return str(object)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "The manager connects specifications and implementations with a manager.\n",
       "\n",
       "    manager = pluggy.PluginManager('example')\n",
       "    \n",
       "Specifications need to be registered, but no implementations exist to the manager.\n",
       "\n",
       "    manager.add_hookspecs(Spec)\n",
       "    \n",
       "    >>> with pytest.raises(TypeError): manager.hook.function(int)\n",
       "        \n",
       "The hook only accepts keyword arguments with names that validate.        \n",
       "\n",
       "    >>> manager.hook.function(object=int)\n",
       "    []"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "The manager connects specifications and implementations with a manager.\n",
    "\n",
    "    manager = pluggy.PluginManager('example')\n",
    "    \n",
    "Specifications need to be registered, but no implementations exist to the manager.\n",
    "\n",
    "    manager.add_hookspecs(Spec)\n",
    "    \n",
    "    >>> with pytest.raises(TypeError): manager.hook.function(int)\n",
    "        \n",
    "The hook only accepts keyword arguments with names that validate.        \n",
    "\n",
    "    >>> manager.hook.function(object=int)\n",
    "    []"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "Include an implementation.    \n",
       "    \n",
       "    manager.register(__import__(__name__))\n",
       "        \n",
       "    >>> manager.hook.function(object=int)\n",
       "    [<class 'type'>]\n",
       "    \n",
       "We cannot register the same object twice.\n",
       "    \n",
       "    >>> with pytest.raises(ValueError): manager.register(__import__(__name__))"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "Include an implementation.    \n",
    "    \n",
    "    manager.register(__import__(__name__))\n",
    "        \n",
    "    >>> manager.hook.function(object=int)\n",
    "    [<class 'type'>]\n",
    "    \n",
    "We cannot register the same object twice.\n",
    "    \n",
    "    >>> with pytest.raises(ValueError): manager.register(__import__(__name__))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "Adding another hook returns more results when the hook is triggered.    \n",
       "    \n",
       "    manager.register(Another)\n",
       "\n",
       "    >>> manager.hook.function(object=int)\n",
       "    [<class 'type'>, \"<class 'int'>\"]"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "Adding another hook returns more results when the hook is triggered.    \n",
    "    \n",
    "    manager.register(Another)\n",
    "\n",
    "    >>> manager.hook.function(object=int)\n",
    "    [<class 'type'>, \"<class 'int'>\"]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/markdown": [
       "Implementations can be unregistered.    \n",
       "    \n",
       "    manager.unregister(__import__(__name__))\n",
       "    >>> [x.function for x in manager.hook.function.get_hookimpls()]\n",
       "    [<function Another.function at ...>]\n",
       "\n",
       "    manager.register(__import__(__name__))\n",
       "\n",
       "    >>> [x.function for x in manager.hook.function.get_hookimpls()]\n",
       "    [<function Another.function at ...>, <function function at ...>]"
      ],
      "text/plain": [
       "<IPython.core.display.Markdown object>"
      ]
     },
     "metadata": {},
     "output_type": "display_data"
    }
   ],
   "source": [
    "Implementations can be unregistered.    \n",
    "    \n",
    "    manager.unregister(__import__(__name__))\n",
    "    >>> [x.function for x in manager.hook.function.get_hookimpls()]\n",
    "    [<function Another.function at ...>]\n",
    "\n",
    "    manager.register(__import__(__name__))\n",
    "\n",
    "    >>> [x.function for x in manager.hook.function.get_hookimpls()]\n",
    "    [<function Another.function at ...>, <function function at ...>]\n"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "pidgy 3",
   "language": "python",
   "name": "pidgy"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.7.3"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 4
}