ab0f5ae0b84bf83849cd55e4839dd508

notebook.ipynb

python-decorator-for-dummies.ipynb

{
  "cells": [
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "view-in-github",
        "colab_type": "text"
      },
      "source": [
        "<a href=\"https://colab.research.google.com/gist/manuelinfosec/ab0f5ae0b84bf83849cd55e4839dd508/python-decorator-for-dummies.ipynb\" target=\"_parent\"><img src=\"https://colab.research.google.com/assets/colab-badge.svg\" alt=\"Open In Colab\"/></a>"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "mGxVwdM7sjfc"
      },
      "source": [
        "## Python Decorators For Dummies\n",
        "> The Best Explanation You Can Ever Find"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "Rdl4sAsssjfk"
      },
      "outputs": [],
      "source": [
        "import discord\n",
        "client = discord.Client(intents=intents)\n",
        "\n",
        "@client.event # take note of this line\n",
        "async def on_ready():\n",
        "    print(f\"Logged in as {client.user}\")\n",
        "\n",
        "@client.event # take note of this line\n",
        "async def on_message(msg):\n",
        "    if msg.content == \"\":\n",
        "        pass\n",
        "# ... SOME MORE CODE ..."
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "VjLllYe9sjfn"
      },
      "source": [
        "### A simple Python function"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "U-Xd6p_Xsjfo",
        "outputId": "b4f87cc9-2e13-48cd-d875-055329a229d8"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "Yes!\n"
          ]
        }
      ],
      "source": [
        "def shout(word='yes'):\n",
        "    return word.capitalize() + '!'\n",
        "\n",
        "print(shout())"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "LF6kuKlYsjfp"
      },
      "source": [
        "### Python function assigned to a variable"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "ybu5aaAqsjfr"
      },
      "outputs": [],
      "source": [
        "scream = shout"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "iEnrIZAosjfs"
      },
      "source": [
        "### Calling the function from a variable"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "ZhhslIrlsjft",
        "outputId": "0b446ef0-3618-4dc7-db1c-5d0d9b085335"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "Yes!\n"
          ]
        }
      ],
      "source": [
        "print(scream())"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "CVRVzKPusjfw",
        "outputId": "d4e5bb9c-2db2-472f-f422-f8c991053d23"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "name 'shout' is not defined\n",
            "Yes!\n"
          ]
        }
      ],
      "source": [
        "# deleting the shout() object\n",
        "del shout\n",
        "\n",
        "try:\n",
        "\t# trying to access the deleted shout() object\n",
        "    print(shout())\n",
        "except NameError as e:\n",
        "    print(e)\n",
        "\n",
        "print(scream())"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "cuggh3Bisjfy"
      },
      "source": [
        "### Defining functions within functions"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "jGJAbWaXsjfz",
        "outputId": "abe579b2-13d3-49ce-fc19-daeb55c07f41"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "yes...\n"
          ]
        }
      ],
      "source": [
        "def talk():\n",
        "    # Defining a function on the fly in `talk` ...\n",
        "    def whisper(word='yes'):\n",
        "        return word.lower() + '...'\n",
        "    # ... and using it right away!\n",
        "    print(whisper())\n",
        "\n",
        "talk()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "pxMRA9o_sjf0"
      },
      "source": [
        "### Internal functions don't exist beyond their scope"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "lvS6hoqFsjf1",
        "outputId": "4d4744ce-96ff-4ab7-c7b6-53fe701c67c0"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "name 'whisper' is not defined\n"
          ]
        }
      ],
      "source": [
        "try:\n",
        "    print(whisper())\n",
        "except NameError as e:\n",
        "    print(e)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "PIHporl1sjf2"
      },
      "source": [
        "### Function returning function"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "zbYkp9h5sjf3"
      },
      "outputs": [],
      "source": [
        "def getTalk(kind='shout'):\n",
        "    # We define functions on the fly\n",
        "    def shout(word='yes'):\n",
        "        return word.capitalize() + '!'\n",
        "\n",
        "    def whisper(word='yes'):\n",
        "        return word.lower() + '...'\n",
        "\n",
        "    # Then we return one of them\n",
        "    if kind == 'shout':\n",
        "\t    # What happened here?\n",
        "        return shout  \n",
        "    else:\n",
        "        return whisper"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "RNAnCm_Rsjf3"
      },
      "source": [
        "### Driver code for the previous cell"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "e4VRNki_sjf4",
        "outputId": "1b45b3dc-6a4a-4121-b2a2-75f5cd43a3b0"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "<function getTalk.<locals>.shout at 0x000001C34384AA60>\n",
            "Yes!\n",
            "yes...\n"
          ]
        }
      ],
      "source": [
        "# Get the function and assign it to a variable\n",
        "talk = getTalk()     \n",
        "\n",
        "# You can see that `talk` is here a function object:\n",
        "print(talk)\n",
        "\n",
        "# The object is the one returned by the function:\n",
        "print(talk())\n",
        "\n",
        "# And you can even use it directly if you feel wild:\n",
        "print(getTalk('whisper')())"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "Qv82FZOtsjf5"
      },
      "source": [
        "### Passing a function as parameter"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "w_8i5ERvsjf5",
        "outputId": "15314c08-cb6e-4202-d084-5b8777768e50"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "I do something before then I call the function you gave me\n",
            "Yes!\n"
          ]
        }
      ],
      "source": [
        "def doSomethingBefore(func): \n",
        "    print(\"I do something before then I call the function you gave me\")\n",
        "    print(func())\n",
        "\n",
        "doSomethingBefore(scream)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "CD6SMYzqsjf6"
      },
      "source": [
        "### Python Decorators The Hard Way"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "G7de6AgRsjf7"
      },
      "outputs": [],
      "source": [
        "def my_shiny_new_decorator(a_function_to_decorate):\n",
        "    # Inside, the decorator defines a function on the fly: the wrapper.\n",
        "    # This function is going to be wrapped around the original function\n",
        "    # so it can execute code before and after it.\n",
        "    def the_wrapper_around_the_original_function():\n",
        "    \n",
        "        # Put here the code you want to be executed BEFORE the original \n",
        "        # function is called\n",
        "        print(\"Before the function runs\")\n",
        "\n",
        "        # Call the function from the parameter here (using parentheses)\n",
        "        a_function_to_decorate()\n",
        "\n",
        "        # Put here the code you want to be executed AFTER the original \n",
        "        # function is called\n",
        "        print(\"After the function runs\")\n",
        "\n",
        "    # At this point, `a_function_to_decorate` HAS NEVER BEEN EXECUTED.\n",
        "    # We return the wrapper function we have just created.\n",
        "    # The wrapper contains the function and the code to execute before\n",
        "    # ...and after. It’s ready to use!\n",
        "    return the_wrapper_around_the_original_function"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "63S9myZYsjf9"
      },
      "source": [
        "### Creating a standalone function"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "i700wFeBsjf-",
        "outputId": "88e27dfe-a4cf-430d-a0fd-293c863376c7"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "I am a stand alone function, don’t you dare modify me\n"
          ]
        }
      ],
      "source": [
        "def a_stand_alone_function():\n",
        "    print(\"I am a stand alone function, don’t you dare modify me\")\n",
        "\n",
        "a_stand_alone_function() "
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "gmZgE-jssjgB"
      },
      "source": [
        "### Wrapping the standalone function around a decorator"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "npOsRV7ysjgB",
        "outputId": "f63ad3d6-5c71-42d2-dab7-45cea4b24946"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "Before the function runs\n",
            "I am a stand alone function, don’t you dare modify me\n",
            "After the function runs\n"
          ]
        }
      ],
      "source": [
        "a_stand_alone_function_decorated = my_shiny_new_decorator(a_stand_alone_function)\n",
        "a_stand_alone_function_decorated()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "gZlefn6msjgC",
        "outputId": "085b7f8a-ce4b-4bb9-b1b1-dfa838861637"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "Before the function runs\n",
            "I am a stand alone function, don’t you dare modify me\n",
            "After the function runs\n"
          ]
        }
      ],
      "source": [
        "a_stand_alone_function = my_shiny_new_decorator(a_stand_alone_function)\n",
        "a_stand_alone_function()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "jRpQxVgnsjgC"
      },
      "source": [
        "### Python decorators the Pythonic way"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "uPL6y1NksjgD",
        "outputId": "9c53013f-1884-4bd5-a53b-d01bdcd932e4"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "Before the function runs\n",
            "Leave me alone\n",
            "After the function runs\n"
          ]
        }
      ],
      "source": [
        "@my_shiny_new_decorator\n",
        "def another_stand_alone_function():\n",
        "    print(\"Leave me alone\")\n",
        "\n",
        "another_stand_alone_function()"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "0X560t5csjgD"
      },
      "outputs": [],
      "source": [
        "another_stand_alone_function = my_shiny_new_decorator(another_stand_alone_function)"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "3rBmaLm6sjgD"
      },
      "source": [
        "### A better example of Python decorators the naive way"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "joP54vcAsjgD",
        "outputId": "95bc361d-8f45-42af-bec3-e5869dba59b3"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "--ham--\n",
            "</''''''\\>\n",
            "#tomatoes#\n",
            "--ham--\n",
            "~salad~\n",
            "<\\______/>\n"
          ]
        }
      ],
      "source": [
        "def bread(func):\n",
        "    def wrapper():\n",
        "        print(\"</''''''\\>\")\n",
        "        func()\n",
        "        print(\"<\\______/>\")\n",
        "    return wrapper\n",
        "\n",
        "def ingredients(func):\n",
        "    def wrapper():\n",
        "        print(\"#tomatoes#\")\n",
        "        func()\n",
        "        print(\"~salad~\")\n",
        "    return wrapper\n",
        "\n",
        "def sandwich(food='--ham--'):\n",
        "    print(food)\n",
        "\n",
        "sandwich()\n",
        "print()\n",
        "# Outputs: --ham--\n",
        "\n",
        "sandwich = bread(ingredients(sandwich))\n",
        "# sandwich is now reference to the decorator\n",
        "# instead of the `--ham` string.\n",
        "sandwich()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "1ozDjNTpsjgE"
      },
      "source": [
        "### Python decorators the Pythonic way"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "szhOZ9LwsjgE",
        "outputId": "b70b4f0d-479d-4426-9f2e-55cf85a89465"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "</''''''\\>\n",
            "#tomatoes#\n",
            "--ham--\n",
            "~salad~\n",
            "<\\______/>\n"
          ]
        }
      ],
      "source": [
        "@bread\n",
        "@ingredients\n",
        "def sandwich(food=\"--ham--\"):\n",
        "\tprint(food)\n",
        "\n",
        "sandwich()"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {
        "id": "wrnNHzBxsjgF"
      },
      "source": [
        "### Unordered decorators"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "id": "yiOe9xXVsjgF",
        "outputId": "b9cd28cb-73f4-4300-9e05-5f60bdbf84a8"
      },
      "outputs": [
        {
          "name": "stdout",
          "output_type": "stream",
          "text": [
            "#tomatoes#\n",
            "</''''''\\>\n",
            "--ham--\n",
            "<\\______/>\n",
            "~salad~\n"
          ]
        }
      ],
      "source": [
        "@ingredients\n",
        "@bread\n",
        "def strange_sandwich(food='--ham--'):\n",
        "    print(food)\n",
        "\n",
        "strange_sandwich()"
      ]
    }
  ],
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