fn_generator

fn_generator.ipynb

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            "text/plain": "v\"1.7.0-DEV.1129\""
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      "cell_type": "markdown",
      "source": "* https://discourse.julialang.org/t/all-ways-to-define-functions-in-julia/45816/15?u=genkuroki\n* https://github.com/JuliaLang/julia/issues/15602"
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    {
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      "cell_type": "code",
      "source": "function fn_generator()\n    if true\n        f() = 0\n    else\n        f(x, y) = x+y\n    end\nend\n\nname = fn_generator()\n\nname(1,2)   # 3",
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      "cell_type": "code",
      "source": "name === fn_generator()",
      "execution_count": 3,
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          "execution_count": 3,
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      "cell_type": "code",
      "source": "name === fn_generator()",
      "execution_count": 4,
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          "execution_count": 4,
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    {
      "metadata": {
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      "cell_type": "code",
      "source": "dump(name)",
      "execution_count": 5,
      "outputs": [
        {
          "output_type": "stream",
          "text": "f (function of type var\"#f#1\")\n",
          "name": "stdout"
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    },
    {
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      "cell_type": "code",
      "source": "methods(name)",
      "execution_count": 6,
      "outputs": [
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          "execution_count": 6,
          "data": {
            "text/plain": "# 2 methods:\n[1] (::var\"#f#1\")() in Main at In[2]:3\n[2] (::var\"#f#1\")(x, y) in Main at In[2]:5",
            "text/html": "# 2 methods:<ul><li> (::<b>var\"#f#1\"</b>)() in Main at In[2]:3</li> <li> (::<b>var\"#f#1\"</b>)(x, y) in Main at In[2]:5</li> </ul>"
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    {
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      "cell_type": "code",
      "source": "name()",
      "execution_count": 7,
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          "execution_count": 7,
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      "cell_type": "code",
      "source": "function make_func()\n    if true\n        f() = 1\n    elseif true\n        f(x) = 2x\n    elseif true\n        f(x, y) = x * y\n    elseif true\n        f(x, y, z) = x * y + z\n    else\n        f(x, y, z, w) = x * y + z * w\n    end\nend\n\nf = make_func()\n\n@show f() f(3) f(3, 4) f(3, 4, 5) f(3, 4, 5, 6);",
      "execution_count": 8,
      "outputs": [
        {
          "output_type": "stream",
          "text": "f() = 1\nf(3) = 6\nf(3, 4) = 12\nf(3, 4, 5) = 17\nf(3, 4, 5, 6) = 42\n",
          "name": "stdout"
        }
      ]
    },
    {
      "metadata": {
        "trusted": true
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      "cell_type": "code",
      "source": "methods(f)",
      "execution_count": 9,
      "outputs": [
        {
          "output_type": "execute_result",
          "execution_count": 9,
          "data": {
            "text/plain": "# 5 methods for generic function \"f\":\n[1] f() in Main at In[8]:3\n[2] f(x) in Main at In[8]:5\n[3] f(x, y) in Main at In[8]:7\n[4] f(x, y, z) in Main at In[8]:9\n[5] f(x, y, z, w) in Main at In[8]:11",
            "text/html": "# 5 methods for generic function <b>f</b>:<ul><li> f() in Main at In[8]:3</li> <li> f(x) in Main at In[8]:5</li> <li> f(x, y) in Main at In[8]:7</li> <li> f(x, y, z) in Main at In[8]:9</li> <li> f(x, y, z, w) in Main at In[8]:11</li> </ul>"
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      "source": "const a=true\nfunction blah()\n    if a==true\n        println(\"here\")\n        f_() = 1\n        return f_\n    elseif a==false\n        println(\"there\")\n        f_() = 2\n        return f_\n    end\nend\nblah()()",
      "execution_count": 10,
      "outputs": [
        {
          "output_type": "stream",
          "text": "here\n",
          "name": "stdout"
        },
        {
          "output_type": "stream",
          "text": "WARNING: Method definition f_() in module Main at In[10]:5 overwritten at In[10]:9.\n",
          "name": "stderr"
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          "execution_count": 10,
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    {
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      "cell_type": "code",
      "source": "function fn_generator2()\n    if false\n        f(x, y) = x+y\n    else\n        f() = 0\n    end\nend\n\ng = fn_generator2()",
      "execution_count": 11,
      "outputs": [
        {
          "output_type": "error",
          "ename": "LoadError",
          "evalue": "UndefVarError: f not defined",
          "traceback": [
            "UndefVarError: f not defined",
            "",
            "Stacktrace:",
            " [1] fn_generator2()",
            "   @ Main .\\In[11]:5",
            " [2] top-level scope",
            "   @ In[11]:9",
            " [3] eval",
            "   @ .\\boot.jl:369 [inlined]",
            " [4] include_string(mapexpr::typeof(REPL.softscope), mod::Module, code::String, filename::String)",
            "   @ Base .\\loading.jl:1110"
          ]
        }
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      "source": "",
      "execution_count": null,
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