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   "source": [
    "[prev: Structure de contrôle](controle-flux.ipynb) | [home](../index.ipynb) | [prev: Lire les erreurs](read-errors.ipynb)"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Structuration du code\n"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Bloc et indentation\n",
    "\n",
    "Les fonctions et les structures de contrôle introduisent l'idée de \"bloc d'instructions\".\n",
    "\n",
    "Elles prennent toutes la même forme:\n",
    "```\n",
    "MotClef ... :\n",
    "    code\n",
    "    code\n",
    "    code\n",
    "```\n",
    "Le '`:`' est à chaque fois suivi d'une **indentation**.\n",
    "\n",
    "C'est l'indentation qui signifie à l'interpréteur où commence et finit le bloc.\n",
    "\n",
    "En Python, l'indentation est signifiante:\n",
    "\n",
    "- chaque ligne d'un bloc doit avoir la même indentation\n",
    "- on ne doit pas mélanger *espaces* et *tabulations* !"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Saut de ligne\n",
    "\n",
    "Une ligne correspond à une instruction.\n",
    "Il n'y a pas de symbole signifiant la fin d'une \"ligne d'instruction\". (eg '`;`' en C)\n",
    "\n",
    "Mais parfois une ligne est trop courte pour une instruction. La solution est alors d'utiliser '`()`', '`[]`' ou '`{}`' sur plusieurs lignes."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[1, 2, 3, 4]"
      ]
     },
     "execution_count": 1,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# une liste sur plusieurs lignes\n",
    "l = [\n",
    "    1,\n",
    "    2,\n",
    "    3,\n",
    "    4,  # la dernière virgule est autorisée et ne change rien\n",
    "]\n",
    "l"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'un': 1, 'deux': 2, 'trois': 3, 'quatre': 4}"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# un dictionnaire sur plusieurs lignes\n",
    "d = {\n",
    "    'un': 1,\n",
    "    'deux': 2,\n",
    "    'trois': 3,\n",
    "    'quatre': 4\n",
    "}\n",
    "d"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# fermer une parenthèse de fonction sur une autre ligne\n",
    "nom_de_fonction_vraiment_trop_long_pour_tout_ecrire_sur_une_ligne = max\n",
    "\n",
    "result = nom_de_fonction_vraiment_trop_long_pour_tout_ecrire_sur_une_ligne(\n",
    "    1, 2, 3, 4\n",
    ")\n",
    "\n",
    "result"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.0845771144278607"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# un calcul trop long\n",
    "a = 1.\n",
    "b = 2.\n",
    "c = 3.\n",
    "d = 4.\n",
    "\n",
    "result = (a + (b ** 3) * 2) / (((c + d) * (a + b)) + ((a + b + c + d) * (a + b + c) * (a + b) * a))\n",
    "\n",
    "result"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "0.0845771144278607"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# c'est l'occasion de structurer un peu tout ça (si possible...)\n",
    "a = 1.\n",
    "b = 2.\n",
    "c = 3.\n",
    "d = 4.\n",
    "\n",
    "result = (\n",
    "    (a + (b ** 3) * 2)\n",
    "    /\n",
    "    (\n",
    "        (c + d) * (a + b)\n",
    "        +\n",
    "        (a + b + c + d) * (a + b + c) * (a + b) * a\n",
    "    )\n",
    ")\n",
    "\n",
    "result"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "*PS : il existe un jeu de caractères pour indiquer la continuation de ligne, mais je n'en parlerai pas.*"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Exercices"
   ]
  }
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