#include "TSelector.h"

# TSelector

class description - source file - inheritance tree (.ps)

## class TSelector : public TObject

| Inheritance Chart:

`TObject`

<-

`TSelector`

<-

`TProofDraw` |

`TSelectorCint` |

`TSelectorDraw` |

        public:

                              TSelector()
                              TSelector(const TSelector&)
                      virtual ~TSelector()
                 virtual void Begin(TTree*)
               static TClass* Class()
          virtual const char* GetOption() const
               virtual TList* GetOutputList() const
            static TSelector* GetSelector(const char* filename)
                virtual Int_t GetStatus() const
                 virtual void Init(TTree*)
              virtual TClass* IsA() const
               virtual Bool_t Notify()
                   TSelector& operator=(const TSelector&)
               virtual Bool_t Process(Int_t)
               virtual Bool_t ProcessCut(Int_t)
                 virtual void ProcessFill(Int_t)
                 virtual void SetInputList(TList* input)
                 virtual void SetObject(TObject* obj)
                 virtual void SetOption(const char* option)
                 virtual void SetStatus(Int_t status)
                 virtual void ShowMembers(TMemberInspector& insp, char* parent)
                 virtual void SlaveBegin(TTree*)
                 virtual void SlaveTerminate()
                 virtual void Streamer(TBuffer& b)
                         void StreamerNVirtual(TBuffer& b)
                 virtual void Terminate()
                  virtual int Version() const

### Data Members

        protected:

             Int_t fStatus  selector status
           TString fOption  option given to TTree::Process
          TObject* fObject  current object if processing object (vs. TTree)
            TList* fInput   list of objects available during processing (on PROOF)
            TList* fOutput  list of objects created during processing (on PROOF)

## Class Description

     A TSelector object is used by the TTree::Draw, TTree::Scan,
      TTree::Loop, TTree::Process to navigate in a TTree and make
      selections.

      The following members functions are called by the TTree functions.
        Init:        Attach a new TTree during the loop
        Begin:       called everytime a loop on the tree(s) starts.
                     a convenient place to create your histograms.

        Notify():    This function is called at the first entry of a new
                     tree in a chain.
        ProcessCut:  called at the beginning of each entry to return a flag
                     true if the entry must be analyzed.
        ProcessFill: called in the entry loop for all entries accepted
                     by Select.
        Terminate:   called at the end of a loop on a TTree.
                     a convenient place to draw/fit your histograms.

TSelector() : TObject()

     Default selector ctor.

~TSelector()

     Selector destructor.

TSelector* GetSelector(const char *filename)

       The code in filename is loaded (interpreted or compiled , see below)
       filename must contain a valid class implementation derived from TSelector,
       where TSelector has the following member functions:

         void TSelector::Init(TTree *t). Called every time a new TTree is attached.
         void TSelector::Begin(). This function is called before looping on the
              events in the Tree. The user can create his histograms in this function.

         Bool_t TSelector::Notify(). This function is called at the first entry
              of a new file in a chain.

         Bool_t TSelector::Process(Int_t entry). This function is called
              to process an event. It is the user's responsability to read
              the corresponding entry in memory (may be just a partial read).
              Once the entry is in memory one can apply a selection and if the
              event is selected histograms can be filled. Processing stops
              when this function returns kFALSE. This function combines the
              next two functions in one, avoiding to have to maintain state
              in the class to communicate between these two funtions.
              See WARNING below about entry.
              This method is used by PROOF.
         Bool_t TSelector::ProcessCut(Int_t entry). This function is called
              before processing entry. It is the user's responsability to read
              the corresponding entry in memory (may be just a partial read).
              The function returns kTRUE if the entry must be processed,
              kFALSE otherwise. See WARNING below about entry.
         void TSelector::ProcessFill(Int_t entry). This function is called for
              all selected events. User fills histograms in this function.
               See WARNING below about entry.
         void TSelector::Terminate(). This function is called at the end of
              the loop on all events.

       WARNING when a selector is used with a TChain:
        in the Process, ProcessCut, ProcessFill function, you must use
        the pointer to the current Tree to call GetEntry(entry).
        entry is always the local entry number in the current tree.
        Assuming that fChain is the pointer to the TChain being processed,
        use fChain->GetTree()->GetEntry(entry);

       If filename is of the form file.C, the file will be interpreted.
       If filename is of the form file.C++, the file file.C will be compiled
          and dynamically loaded. The corresponding binary file and shared
          library will be deleted at the end of the function.
       If filename is of the form file.C+, the file file.C will be compiled
          and dynamically loaded. At next call, if file.C is older than file.o
          and file.so, the file.C is not compiled, only file.so is loaded.

       The static function returns a pointer to a TSelector object

### Inline Functions

                    int Version() const
                   void Init(TTree*)
                   void Begin(TTree*)
                   void SlaveBegin(TTree*)
                 Bool_t Notify()
            const char* GetOption() const
                  Int_t GetStatus() const
                 Bool_t ProcessCut(Int_t)
                   void ProcessFill(Int_t)
                 Bool_t Process(Int_t)
                   void SetOption(const char* option)
                   void SetObject(TObject* obj)
                   void SetInputList(TList* input)
                   void SetStatus(Int_t status)
                 TList* GetOutputList() const
                   void SlaveTerminate()
                   void Terminate()
                TClass* Class()
                TClass* IsA() const
                   void ShowMembers(TMemberInspector& insp, char* parent)
                   void Streamer(TBuffer& b)
                   void StreamerNVirtual(TBuffer& b)
              TSelector TSelector(const TSelector&)
             TSelector& operator=(const TSelector&)

Author: Rene Brun 05/02/97
Last update: root/treeplayer:$Name: $:$Id: TSelector.cxx,v 1.14 2003/12/19 09:31:52 brun Exp $
Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *