{
 "cells": [
  {
   "cell_type": "markdown",
   "id": "70b3c948",
   "metadata": {},
   "source": [
    "# Functor\n",
    "Example to create class Functor\n",
    "\n",
    "\n",
    "\n",
    "\n",
    "**Author:** Omar Zapata  \n",
    "<i><small>This notebook tutorial was automatically generated with <a href= \"https://github.com/root-project/root/blob/master/documentation/doxygen/converttonotebook.py\">ROOTBOOK-izer</a> from the macro found in the ROOT repository  on Tuesday, May 19, 2026 at 08:27 PM.</small></i>"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "28444b3d",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:37.903275Z",
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     "shell.execute_reply": "2026-05-19T20:27:38.235486Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "input_line_44:2:32: error: expected ';' after expression\n",
      " ROOTR_EXPOSED_CLASS(MyFunctor)\n",
      "                               ^\n",
      "                               ;\n",
      "input_line_44:4:1: error: use of undeclared identifier 'R'\n",
      "R\n",
      "^\n"
     ]
    }
   ],
   "source": [
    "ROOTR_EXPOSED_CLASS(MyFunctor)\n",
    "\n",
    "R"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "e0fea372",
   "metadata": {},
   "source": [
    " Definition of a helper function: "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "fe9417a8",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.238151Z",
     "iopub.status.busy": "2026-05-19T20:27:38.238019Z",
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     "shell.execute_reply": "2026-05-19T20:27:38.242715Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "input_line_53:2:9: fatal error: 'TRInterface.h' file not found\n",
      "#include<TRInterface.h>\n",
      "        ^~~~~~~~~~~~~~~\n"
     ]
    }
   ],
   "source": [
    "%%cpp -d\n",
    "\n",
    "#include<TRInterface.h>\n",
    "#include<TMath.h>\n",
    "\n",
    "typedef Double_t (*Function)(Double_t);\n",
    "\n",
    "//Functor class with the function inside\n",
    "class MyFunctor{\n",
    "public:\n",
    "   MyFunctor() {\n",
    "      status=false;\n",
    "      f=TMath::BesselY1;\n",
    "   }\n",
    "\n",
    "   void setFunction(Function fun) {\n",
    "    f=fun;\n",
    "    status=true;\n",
    "   }\n",
    "\n",
    "   Bool_t getStatus(){return status;}\n",
    "\n",
    "   Double_t doEval(Double_t x) {\n",
    "      return f(x);\n",
    "   }\n",
    "\n",
    "private:\n",
    "   Function f;\n",
    "   Bool_t status;\n",
    "};"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "970fb85a",
   "metadata": {},
   "source": [
    " this macro exposes the class into R's enviornment\n",
    "and lets you pass objects directly.\n",
    "Macro to create a module\n",
    " "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "4d0b4f93",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.244635Z",
     "iopub.status.busy": "2026-05-19T20:27:38.244493Z",
     "iopub.status.idle": "2026-05-19T20:27:38.247332Z",
     "shell.execute_reply": "2026-05-19T20:27:38.246885Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "input_line_54:1:13: error: use of undeclared identifier 'MyFunctorModule'\n",
      "OOTR_MODULE(MyFunctorModule) {\n",
      "            ^\n"
     ]
    }
   ],
   "source": [
    "%%cpp -d\n",
    "OOTR_MODULE(MyFunctorModule) {\n",
    "   ROOT::R::class_<MyFunctor>( \"MyFunctor\" )\n",
    "   //creating a default constructor\n",
    "   .constructor()\n",
    "   //adding the method doEval to evaluate the internal function\n",
    "   .method( \"doEval\", &MyFunctor::doEval )\n",
    "   .method( \"getStatus\", &MyFunctor::getStatus)\n",
    "   ;\n",
    "}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "4feead38",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.248689Z",
     "iopub.status.busy": "2026-05-19T20:27:38.248550Z",
     "iopub.status.idle": "2026-05-19T20:27:38.457252Z",
     "shell.execute_reply": "2026-05-19T20:27:38.456598Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "input_line_55:2:8: error: 'R' is not a class, namespace, or enumeration\n",
      " ROOT::R::TRInterface &r=ROOT::R::TRInterface::Instance();\n",
      "       ^\n",
      "input_line_55:2:8: note: 'R' declared here\n",
      "input_line_55:2:32: error: no member named 'R' in namespace 'ROOT'\n",
      " ROOT::R::TRInterface &r=ROOT::R::TRInterface::Instance();\n",
      "                         ~~~~~~^\n"
     ]
    }
   ],
   "source": [
    "ROOT::R::TRInterface &r=ROOT::R::TRInterface::Instance();"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "94ee2925",
   "metadata": {},
   "source": [
    "Creating functor with default function TMath::BesselY1\n",
    "and status false from R's environment\n",
    "Loading module into R's enviornment"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "8613d8c9",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.458837Z",
     "iopub.status.busy": "2026-05-19T20:27:38.458710Z",
     "iopub.status.idle": "2026-05-19T20:27:38.785663Z",
     "shell.execute_reply": "2026-05-19T20:27:38.785006Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "IncrementalExecutor::executeFunction: symbol '_ZN5cling7runtime8internal9EvaluateTIvEET_PNS1_15DynamicExprInfoEPN5clang11DeclContextE' unresolved while linking [cling interface function]!\n",
      "You are probably missing the definition of void cling::runtime::internal::EvaluateT<void>(cling::runtime::internal::DynamicExprInfo*, clang::DeclContext*)\n",
      "Maybe you need to load the corresponding shared library?\n"
     ]
    }
   ],
   "source": [
    "r[\"MyFunctorModule\"]<<LOAD_ROOTR_MODULE(MyFunctorModule);"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "59cd1da3",
   "metadata": {},
   "source": [
    "creating a class variable from module"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "eaeae5c0",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.787298Z",
     "iopub.status.busy": "2026-05-19T20:27:38.787170Z",
     "iopub.status.idle": "2026-05-19T20:27:38.993194Z",
     "shell.execute_reply": "2026-05-19T20:27:38.992545Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "cling JIT session error: Failed to materialize symbols: { (main, { _ZN5cling7runtime8internal15DynamicExprInfoC1EPKcPPvb }) }\n"
     ]
    }
   ],
   "source": [
    "r<<\"MyFunctor <- MyFunctorModule$MyFunctor\";"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "268b1595",
   "metadata": {},
   "source": [
    "creating a MyFunctor's object"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "d9250459",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:38.994844Z",
     "iopub.status.busy": "2026-05-19T20:27:38.994714Z",
     "iopub.status.idle": "2026-05-19T20:27:39.200855Z",
     "shell.execute_reply": "2026-05-19T20:27:39.199970Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "cling JIT session error: Failed to materialize symbols: { (main, { _ZN5cling7runtime8internal15DynamicExprInfoC1EPKcPPvb }) }\n"
     ]
    }
   ],
   "source": [
    "r<<\"u <- new(MyFunctor)\";"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b9cd2ffd",
   "metadata": {},
   "source": [
    "printing status"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "fc48abf0",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:39.202407Z",
     "iopub.status.busy": "2026-05-19T20:27:39.202275Z",
     "iopub.status.idle": "2026-05-19T20:27:39.408449Z",
     "shell.execute_reply": "2026-05-19T20:27:39.407558Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "cling JIT session error: Failed to materialize symbols: { (main, { _ZN5cling7runtime8internal15DynamicExprInfoC1EPKcPPvb }) }\n"
     ]
    }
   ],
   "source": [
    "r<<\"print(u$getStatus())\";"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "41a6b4a9",
   "metadata": {},
   "source": [
    "printing values from Functor and Function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "672acdf1",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:39.410003Z",
     "iopub.status.busy": "2026-05-19T20:27:39.409860Z",
     "iopub.status.idle": "2026-05-19T20:27:39.615808Z",
     "shell.execute_reply": "2026-05-19T20:27:39.615153Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "cling JIT session error: Failed to materialize symbols: { (main, { _ZN5cling7runtime8internal15DynamicExprInfoC1EPKcPPvb }) }\n"
     ]
    }
   ],
   "source": [
    "r<<\"print(sprintf('value in R = %f',u$doEval( 1 )))\";\n",
    "std::cout<<\"value in ROOT = \"<<TMath::BesselY1(1)<<std::endl;"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "4bfad160",
   "metadata": {},
   "source": [
    "creating a MyFunctor's object and passing objects to R's\n",
    "enviornment, the status should be true because it is not\n",
    "using the default function"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "0cd53a7e",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:39.617523Z",
     "iopub.status.busy": "2026-05-19T20:27:39.617394Z",
     "iopub.status.idle": "2026-05-19T20:27:39.822674Z",
     "shell.execute_reply": "2026-05-19T20:27:39.822083Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "input_line_61:2:2: error: unknown type name 'MyFunctor'\n",
      " MyFunctor functor;\n",
      " ^\n",
      "input_line_61:4:1: error: use of undeclared identifier 'r'\n",
      "r[\"functor\"]<<functor;\n",
      "^\n"
     ]
    }
   ],
   "source": [
    "MyFunctor functor;\n",
    "functor.setFunction(TMath::Erf);\n",
    "r[\"functor\"]<<functor;"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "fdac633d",
   "metadata": {},
   "source": [
    "printing the status that should be true"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "e2cf47d5",
   "metadata": {
    "collapsed": false,
    "execution": {
     "iopub.execute_input": "2026-05-19T20:27:39.823890Z",
     "iopub.status.busy": "2026-05-19T20:27:39.823773Z",
     "iopub.status.idle": "2026-05-19T20:27:40.028973Z",
     "shell.execute_reply": "2026-05-19T20:27:40.028430Z"
    }
   },
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "cling JIT session error: Failed to materialize symbols: { (main, { _ZN5cling7runtime8internal15DynamicExprInfoC1EPKcPPvb }) }\n"
     ]
    }
   ],
   "source": [
    "r<<\"print(functor$getStatus())\";\n",
    "r<<\"print(sprintf('value in R = %f',functor$doEval( 1 )))\";\n",
    "std::cout<<\"value in ROOT = \"<<TMath::Erf(1)<<std::endl;"
   ]
  }
 ],
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