20170327-cohpy-max-morlocke-memory-leaks.ipynb

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   "source": [
    "# Max Morlocke\n",
    "# [Memory Leaks (in Python)](https://github.com/kedlav/presentations/blob/master/memory_leaks.pdf)\n"
   ]
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    "---\n",
    "Mutable default arguments are usually a bug that can gobble memory.\n",
    "\n",
    "For example,"
   ]
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    "def append_to(element, target=[]):\n",
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     "name": "stdout",
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     "text": [
      "['hello']\n"
     ]
    }
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   "source": [
    "a = append_to('hello')\n",
    "print(a)"
   ]
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     "text": [
      "['hello', 'world']\n"
     ]
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    "b = append_to('world')\n",
    "print(b)"
   ]
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       "['hello', 'world']"
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    "a"
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       "True"
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   "source": [
    "a is b"
   ]
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   "source": [
    "A better way of initializing to mutable data is shown below."
   ]
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   "source": [
    "def append_to(element, target=None):\n",
    "    if target is None:\n",
    "        target = []\n",
    "    target.append(element)\n",
    "    return target"
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     "text": [
      "['hello']\n"
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    "c = append_to('hello')\n",
    "print(c)"
   ]
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   "cell_type": "code",
   "execution_count": 8,
   "metadata": {
    "collapsed": false,
    "deletable": true,
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   "outputs": [
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     "name": "stdout",
     "output_type": "stream",
     "text": [
      "['world']\n"
     ]
    }
   ],
   "source": [
    "d = append_to('world')\n",
    "print(d)"
   ]
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   "cell_type": "code",
   "execution_count": 9,
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    "collapsed": false,
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      "text/plain": [
       "['hello']"
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     "execution_count": 9,
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    "c"
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