Decorators.ipynb

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      "# Decorators and Properties\n",
      "\n",
      "### Austin Godber\n",
      "#### @godber\n",
      "\n",
      "July 2014"
     ]
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      "# PEP 318 - Python 2.4\n",
      "\n",
      "* A decorator is a function that returns another function\n",
      "* Typically modifies the behavior of passed in function\n",
      "* Works on functions or methods\n",
      "* http://legacy.python.org/dev/peps/pep-0318/\n",
      "* https://wiki.python.org/moin/PythonDecorators"
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     "source": [
      "# Background\n",
      "\n",
      "* Functions are objects.\n",
      "* Functions can be passed in as arguments and returned."
     ]
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     "source": [
      "# Identity Decorator (from @BrianHoldefehr)"
     ]
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      "def identity_decorator(func):\n",
      "    def wrapper():\n",
      "        func()\n",
      "    return wrapper\n",
      "\n",
      "def a_function():\n",
      "    print \"I'm a normal function.\"\n",
      "\n",
      "decorated_function = identity_decorator(a_function)\n",
      "decorated_function()"
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        "I'm a normal function.\n"
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     "source": [
      "## Using the @ notation"
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      "@identity_decorator\n",
      "def another_decorated_function():\n",
      "    print \"I too am a normal function\"\n",
      "    \n",
      "another_decorated_function()"
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        "I too am a normal function\n"
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     "source": [
      "# Notation\n",
      "\n",
      "Using the `@` and placing it **before** the function to be decorated puts it **in-your-face**.\n",
      "\n",
      "-  Guido van Rossum (Fri Aug 6 16:45:51 CEST 2004)\n",
      "\n",
      "Highlights the function modification instead of burying it at the end as a variable assignment.\n",
      "\n"
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     "source": [
      "# Decorator Ordering\n",
      "\n",
      "```\n",
      "@dec2\n",
      "@dec1\n",
      "def function1():\n",
      "    pass\n",
      "```\n",
      "\n",
      "equivalent to\n",
      "\n",
      "```\n",
      "def function1():\n",
      "    pass\n",
      "func = dec2(dec1(function1))\n",
      "```"
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     "source": [
      "# Passing Arguments to Decorators\n",
      "\n",
      "You can do it."
     ]
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     "input": [
      "def increment(val):\n",
      "    return val + 1\n",
      "\n",
      "increment(1)"
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        "2"
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     "source": [
      "# In Use\n",
      "\n",
      "* Click `@click.command`\n",
      "* Flask `@app.route`"
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