Creating a New Node Type

The heart of FARFALLA is its extensibility - programmers may define new classes to manage their data, and incorporate nodes of the new class onto FARFALLA trees with nodes of other types. However, many FARFALLA programmers will only use FARFALLA node types created by others and do not need to understand everything in this section.

In C++ , class definitions are kept in header files called classname.h. You will want to create a header file for every class you create. The header file should contain several things.

• an F_NodeType variable containing the four-letter identification of the new class
• the code to inform the compiler that the new class inherits from F_Node
• a very special member function called a constructor (explained below)
• most importantly, the data - the names and types of all the data members
• simple member functions called print() and info()
• a member function called IOData() that knows how to move data from the class variables to disk and back
• a function to create a new member of the class
• an object to cause the class to be declared to FARFALLA

The file erpNode.h is included here for reference. Each element will be discussed individually in the following sections.

static F_NodeType erpType = "Erp ";

class erpNode : public F_Node {

public:

  erpNode() { type = erpType; version = 0;}

  unsigned char version;
  
  short boxnum;                 // ERP BOX

  short adc0u;                  // ADC 0 side Unattenuated
  short adc1u;                  // ADC 1 side Unattenuated
  short tdc0h;                  // TDC 0 side high
  short tdc1h;                  // TDC 1 side high
  short adc0a;                  // ADC 0 side attenuated
  short adc1a;                  // ADC 1 side attenuated
  short tdc0l;                  // TDC 0 side low
  short tdc1l;                  // TDC 1 side low

  float energy;                 // ERP Energy
  float time;                   // Time of BOX hit rel. to stop
  float posh;                   // Box position from tdch

  virtual inline void print(ostream& o)
  {
    o << "Erp Node v" << (short) version << endl << endl;
    o << "Box Num: " << boxnum << endl;
    o << "ADC0u:   " << adc0u  << endl;
    o << "ADC1u:   " << adc1u  << endl;
    o << "ADC0a:   " << adc0a  << endl;
    o << "ADC1a:   " << adc1a  << endl;
    o << "TDC0h:   " << tdc0h  << endl;
    o << "TDC1h:   " << tdc1h  << endl;
    o << "TDC0l:   " << tdc0l  << endl;
    o << "TDC1l:   " << tdc1l  << endl;
    o << "Energy:  " << energy << endl;
    o << "Time:    " << time   << endl;
    o << "Pos High:" << posh   << endl << endl;
  }

  virtual inline void info(ostream& o)
  {
    o << "Box " << boxnum << "; Energy " << energy << "; Time " << time <<
      "; Posh " << posh << endl;
  }
  
protected:
  
  virtual inline void IOData(iostream& file, F_inout choice,
                             F_length& nodeLength)
  {
    F_IORec(file,version,choice,nodeLength);
    F_IORec(file,boxnum,choice,nodeLength);
    F_IORec(file,adc0u,choice,nodeLength);
    F_IORec(file,adc1u,choice,nodeLength);
    F_IORec(file,tdc0h,choice,nodeLength); 
    F_IORec(file,tdc1h,choice,nodeLength);
    F_IORec(file,adc0a,choice,nodeLength);
    F_IORec(file,adc1a,choice,nodeLength);
    F_IORec(file,tdc0l,choice,nodeLength);
    F_IORec(file,tdc1l,choice,nodeLength);
    F_IORec(file,energy,choice,nodeLength);
    F_IORec(file,time,choice,nodeLength);
    F_IORec(file,posh,choice,nodeLength);
  }
};

inline F_Node* newErpNode() {return new erpNode;}
static F_classDeclare declareErp(erpType,newErpNode);

• The F_NodeType
• Inheritance from F_NodeClass
• The Constructor
• The Data
• print() and info()
• IOData()
• The Creation Function
• Declaration Object
• Unknown Node Types