11_dekoratory.ipynb

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   "source": [
    "# Język Python\n",
    "## Dekoratory"
   ]
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   "source": [
    "def say_even_more(*args, **kwargs):\n",
    "    print(args)  # krotka\n",
    "    print(kwargs)  # słownik"
   ]
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   "source": [
    "import logging\n",
    "logging.basicConfig(level=logging.DEBUG)\n",
    "\n",
    "def logged(f):\n",
    "    def logged_f(*args, **kwargs):\n",
    "        logging.debug(\"Called {!r} with params {} and {}\".format(f.__name__, args, kwargs))\n",
    "        ret_val = f(*args, **kwargs)\n",
    "        logging.debug(\"{!r} returned {!r}\".format(f.__name__, ret_val))\n",
    "        return ret_val\n",
    "    return logged_f"
   ]
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   "source": [
    "say_even_more = logged(say_even_more)"
   ]
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   "source": [
    "say_even_more(1, 2)"
   ]
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   "source": [
    "@logged\n",
    "def g(n):\n",
    "    print(\"Another simple method printing {}.\".format(n))"
   ]
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   "source": [
    "g(2)"
   ]
  },
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   "outputs": [],
   "source": [
    "def synchronized(f):\n",
    "    pass"
   ]
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   "source": [
    "# Example ...\n",
    "@synchronized\n",
    "@logged\n",
    "def myfunc(arg1, arg2, *args):\n",
    "    # ...do something\n",
    "    pass"
   ]
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   "source": [
    "def entry_exit(f):\n",
    "    def new_f():\n",
    "        print(\"Entering\", f.__name__)\n",
    "        f()\n",
    "        print(\"Exited\", f.__name__)\n",
    "    return new_f"
   ]
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   "cell_type": "code",
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   "source": [
    "@entry_exit\n",
    "def func1():\n",
    "    print(\"inside func1()\")\n",
    "func1()"
   ]
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   "source": [
    "class EntryExit:\n",
    "    \n",
    "    def __init__(self, f):\n",
    "        self.f = f\n",
    "        self.n = 0\n",
    "    \n",
    "    def __call__(self):\n",
    "        self.n += 1\n",
    "        print(\"Entering\", self.f.__name__, self.n, \"time\" + (\"s\" if self.n > 1 else \"\"))\n",
    "        self.f()\n",
    "        print(\"Exited\", self.f.__name__)\n",
    "\n",
    "        \n",
    "@EntryExit\n",
    "def func1():\n",
    "    print(\"inside func1()\")"
   ]
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   "source": [
    "type(func1)"
   ]
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    "func1()"
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   "source": [
    "from random import randint\n",
    "\n",
    "@moving_avg(10)\n",
    "def foo():\n",
    "    return randint(1, 100)\n",
    "\n",
    "print([foo() for _ in range(20)])"
   ]
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   "source": [
    "def foo():\n",
    "    return randint(1, 100)\n",
    "\n",
    "dec = moving_avg(4)\n",
    "foo = dec(foo)"
   ]
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   "source": [
    "def moving_avg(window_size):\n",
    "    def decorator(f):\n",
    "        window = []\n",
    "        def decorated(*args, **kwargs):\n",
    "            nonlocal window\n",
    "            window += [f(*args, **kwargs)]\n",
    "            window = window[-window_size:]\n",
    "            return sum(window)/len(window)\n",
    "        return decorated\n",
    "    return decorator"
   ]
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   "source": [
    "class Decorator:\n",
    "    \n",
    "    def __init__(self, arg):\n",
    "        self.arg = arg\n",
    "    \n",
    "    def __call__(self, cls):\n",
    "        class Wrapped(cls):\n",
    "            classattr = self.arg\n",
    "            def new_method(self, value):\n",
    "                return value * 2\n",
    "        return Wrapped"
   ]
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   "source": [
    "@Decorator(\"decorated class\")\n",
    "class TestClass:\n",
    "    \n",
    "    def new_method(self, value):\n",
    "        return value * 3\n",
    "    \n",
    "t = TestClass()\n",
    "\n",
    "print(t.new_method(5))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "t.classattr"
   ]
  },
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   "source": [
    "def my_decorator(f):\n",
    "    def wrapper(*args, **kwargs):\n",
    "        print('Calling decorated function')\n",
    "        return f(*args, **kwargs)\n",
    "    return wrapper\n",
    "\n",
    "@my_decorator\n",
    "def example():\n",
    "    \"\"\"Docstring\"\"\"\n",
    "    print('Called example function')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "example()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
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   },
   "outputs": [],
   "source": [
    "print(example.__doc__)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
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   },
   "outputs": [],
   "source": [
    "print(example.__name__)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "def my_decorator(f):\n",
    "    def wrapper(*args, **kwargs):\n",
    "        print('Calling decorated function')    \n",
    "        return f(*args, **kwargs)\n",
    "    wrapper.__doc__ = f.__doc__\n",
    "    wrapper.__name__ = f.__name__\n",
    "    return wrapper\n",
    "\n",
    "@my_decorator\n",
    "def example():\n",
    "    \"\"\"Docstring\"\"\"\n",
    "    print('Called example function')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "example()\n",
    "print(example.__doc__)\n",
    "print(example.__name__)"
   ]
  },
  {
   "cell_type": "markdown",
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   "source": [
    "Bazinga!"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
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   "outputs": [],
   "source": [
    "from functools import wraps\n",
    "\n",
    "def my_decorator(f):\n",
    "    @wraps(f)\n",
    "    def wrapper(*args, **kwds):\n",
    "        print('Calling decorated function')\n",
    "        return f(*args, **kwds)\n",
    "    return wrapper\n",
    "\n",
    "@my_decorator\n",
    "def example():\n",
    "    \"\"\"Docstring\"\"\"\n",
    "    print('Called example function')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "slideshow": {
     "slide_type": "fragment"
    }
   },
   "outputs": [],
   "source": [
    "print(example.__doc__)\n",
    "print(example.__name__)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {
    "slideshow": {
     "slide_type": "subslide"
    }
   },
   "source": [
    "* przy pisaniu dekoratorów **powinniśmy** dekorować funkcję dekorującą dekoratorem *wraps* z funkcją dekorowaną jako argument\n",
    "* przypiszemy nowej funkcji wszystkie potrzebne atrybuty starej funkcji, żeby mogła ją całkowicie podmienić "
   ]
  }
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