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    "<p style=\"float: left;\"><a href=\"abstract-types.ipynb\" target=\"_blank\">Previous</a></p>\n",
    "<p style=\"float: right;\"><a href=\"self-types.ipynb\" target=\"_blank\">Next</a></p>\n",
    "<p style=\"text-align:center;\">Tour of Scala</p>\n",
    "<div style=\"clear: both;\"></div>\n",
    "\n",
    "# Compound Types\n",
    "\n",
    "Sometimes it is necessary to express that the type of an object is a subtype of several other types. In Scala this can be expressed with the help of *compound types*, which are intersections of object types.\n",
    "\n",
    "Suppose we have two traits `Cloneable` and `Resetable`:"
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       "defined \u001b[32mtrait\u001b[39m \u001b[36mCloneable\u001b[39m\n",
       "defined \u001b[32mtrait\u001b[39m \u001b[36mResetable\u001b[39m"
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    "trait Cloneable extends java.lang.Cloneable {\n",
    "  override def clone(): Cloneable = {\n",
    "    super.clone().asInstanceOf[Cloneable]\n",
    "  }\n",
    "}\n",
    "trait Resetable {\n",
    "  def reset: Unit\n",
    "}"
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   "source": [
    "Now suppose we want to write a function `cloneAndReset` which takes an object, clones it and resets the original object:"
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    "```scala\n",
    "def cloneAndReset(obj: ?): Cloneable = {\n",
    "  val cloned = obj.clone()\n",
    "  obj.reset\n",
    "  cloned\n",
    "}\n",
    "```\n"
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   "source": [
    "The question arises what the type of the parameter `obj` is. If it's `Cloneable` then the object can be `clone`d, but not `reset`; if it's `Resetable` we can `reset` it, but there is no `clone` operation. To avoid type casts in such a situation, we can specify the type of `obj` to be both `Cloneable` and `Resetable`. This compound type is written like this in Scala: `Cloneable with Resetable`.\n",
    "\n",
    "Here's the updated function:"
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   "metadata": {},
   "source": [
    "```scala\n",
    "def cloneAndReset(obj: Cloneable with Resetable): Cloneable = {\n",
    "  //...\n",
    "}\n",
    "```\n"
   ]
  },
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   "metadata": {},
   "source": [
    "Compound types can consist of several object types and they may have a single refinement which can be used to narrow the signature of existing object members.\n",
    "The general form is: `A with B with C ... { refinement }`\n",
    "\n",
    "An example for the use of refinements is given on the page about [class composition with mixins](mixin-class-composition.ipynb).\n",
    "<p style=\"float: left;\"><a href=\"abstract-types.ipynb\" target=\"_blank\">Previous</a></p>\n",
    "<p style=\"float: right;\"><a href=\"self-types.ipynb\" target=\"_blank\">Next</a></p>\n",
    "<p style=\"text-align:center;\">Tour of Scala</p>\n",
    "<div style=\"clear: both;\"></div>"
   ]
  }
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