functions modifying their arguments

functions modifying their arguments.ipynb

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      "source": "a = [1, 2, 3]",
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      "source": "function double_bugged!(a)\n    a = 2a\nend\n\n@show a = [1, 2, 3]\ndouble_bugged!(a)\n@show a;",
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      "source": "function double_by_for!(a)\n    for i in eachindex(a)\n        a[i] = 2a[i]\n    end\nend\n\n@show a = [1, 2, 3]\ndouble_by_for!(a)\n@show a;",
      "execution_count": 3,
      "outputs": [
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          "output_type": "stream",
          "text": "a = [1, 2, 3] = [1, 2, 3]\na = [2, 4, 6]\n",
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      "cell_type": "code",
      "source": "function double_by_dot!(a)\n    a .= 2 .* a\nend\n\n@show a = [1, 2, 3]\ndouble_by_dot!(a)\n@show a;",
      "execution_count": 4,
      "outputs": [
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          "name": "stdout"
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      "source": "function double_bugged_by_dot!(a)\n    a = 2 .* a\nend\n\n@show a = [1, 2, 3]\ndouble_bugged_by_dot!(a)\n@show a;",
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    {
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      "cell_type": "code",
      "source": "function double_by_dot!(a)\n    @. a = 2a\nend\n\n@show a = [1, 2, 3]\ndouble_by_dot!(a)\n@show a;",
      "execution_count": 6,
      "outputs": [
        {
          "output_type": "stream",
          "text": "a = [1, 2, 3] = [1, 2, 3]\na = [2, 4, 6]\n",
          "name": "stdout"
        }
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      "cell_type": "code",
      "source": "double!(a) = @. a = 2a\n\n@show a = [1, 2, 3]\ndouble!(a)\n@show a;",
      "execution_count": 7,
      "outputs": [
        {
          "output_type": "stream",
          "text": "a = [1, 2, 3] = [1, 2, 3]\na = [2, 4, 6]\n",
          "name": "stdout"
        }
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      "cell_type": "code",
      "source": "mutable struct Foo{Ta}\n    a::Ta\nend\n\nfunction double!(x::Foo)\n    x.a = 2x.a\nend\n\n@show x = Foo(123)\ndouble!(x)\n@show x;",
      "execution_count": 8,
      "outputs": [
        {
          "output_type": "stream",
          "text": "x = Foo(123) = Foo{Int64}(123)\nx = Foo{Int64}(246)\n",
          "name": "stdout"
        }
      ]
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