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TNotifyLink< Type > Class Template Reference

template<class Type>
class TNotifyLink< Type >

A node in a doubly linked list of subscribers to TChain notifications.

TObject has a virtual TObject::Notify() method that takes no parameters and returns a boolean. By default the method does nothing, and different objects in ROOT use this method for different purposes.

TChain uses Notify to implement a callback mechanism that notifies interested parties (subscribers) when the chain switches to a new sub-tree. In practice it calls the Notify() method of its fNotify data member from TChain::LoadTree(). However there could be several different objects interested in knowing that a given TChain switched to a new tree. TNotifyLink can be used to build a linked list of subscribers: calling TNotifyLink::Notify() on the head node of the list propagates the call to all subscribers in the list.

Example usage:

TNotifyLink l(subscriber); // subscriber must implement `Notify()`
l.PrependLink(chain); // prepends `l` to the list of notify links of the chain
TLine l
Definition textangle.C:4
Note
TChain does not explicitly enforce that its fNotify data member be the head node of a list of TNotifyLinks, but that is the case in practice at least when using TTreeReader or RDataFrame to process the chain.
TChain does not take ownership of the TNotifyLink and the TNotifyLink does not take ownership of the subscriber object.

Definition at line 127 of file TNotifyLink.h.

Public Member Functions

 TNotifyLink (Type *subscriber)
 
TClassIsA () const override
 
Bool_t Notify () override
 Call Notify on our subscriber and propagate the call to the next link.
 
void Streamer (TBuffer &) override
 Stream an object of class TObject.
 
void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
 
- Public Member Functions inherited from TNotifyLinkBase
void Clear (Option_t *="") override
 
TObjectGetNext () const
 
TClassIsA () const override
 
Bool_t IsLinked ()
 
template<class Chain >
void PrependLink (Chain &chain)
 Set this link as the head of the chain's list of notify subscribers.
 
template<class Chain >
void RemoveLink (Chain &chain)
 Remove this link from a chain's list of notify subscribers.
 
void Streamer (TBuffer &) override
 Stream an object of class TObject.
 
void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
 
- Public Member Functions inherited from TObject
 TObject ()
 TObject constructor.
 
 TObject (const TObject &object)
 TObject copy ctor.
 
virtual ~TObject ()
 TObject destructor.
 
void AbstractMethod (const char *method) const
 Use this method to implement an "abstract" method that you don't want to leave purely abstract.
 
virtual void AppendPad (Option_t *option="")
 Append graphics object to current pad.
 
virtual void Browse (TBrowser *b)
 Browse object. May be overridden for another default action.
 
ULong_t CheckedHash ()
 Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.
 
virtual const char * ClassName () const
 Returns name of class to which the object belongs.
 
virtual TObjectClone (const char *newname="") const
 Make a clone of an object using the Streamer facility.
 
virtual Int_t Compare (const TObject *obj) const
 Compare abstract method.
 
virtual void Copy (TObject &object) const
 Copy this to obj.
 
virtual void Delete (Option_t *option="")
 Delete this object.
 
virtual Int_t DistancetoPrimitive (Int_t px, Int_t py)
 Computes distance from point (px,py) to the object.
 
virtual void Draw (Option_t *option="")
 Default Draw method for all objects.
 
virtual void DrawClass () const
 Draw class inheritance tree of the class to which this object belongs.
 
virtual TObjectDrawClone (Option_t *option="") const
 Draw a clone of this object in the current selected pad with: gROOT->SetSelectedPad(c1).
 
virtual void Dump () const
 Dump contents of object on stdout.
 
virtual void Error (const char *method, const char *msgfmt,...) const
 Issue error message.
 
virtual void Execute (const char *method, const char *params, Int_t *error=nullptr)
 Execute method on this object with the given parameter string, e.g.
 
virtual void Execute (TMethod *method, TObjArray *params, Int_t *error=nullptr)
 Execute method on this object with parameters stored in the TObjArray.
 
virtual void ExecuteEvent (Int_t event, Int_t px, Int_t py)
 Execute action corresponding to an event at (px,py).
 
virtual void Fatal (const char *method, const char *msgfmt,...) const
 Issue fatal error message.
 
virtual TObjectFindObject (const char *name) const
 Must be redefined in derived classes.
 
virtual TObjectFindObject (const TObject *obj) const
 Must be redefined in derived classes.
 
virtual Option_tGetDrawOption () const
 Get option used by the graphics system to draw this object.
 
virtual const char * GetIconName () const
 Returns mime type name of object.
 
virtual const char * GetName () const
 Returns name of object.
 
virtual char * GetObjectInfo (Int_t px, Int_t py) const
 Returns string containing info about the object at position (px,py).
 
virtual Option_tGetOption () const
 
virtual const char * GetTitle () const
 Returns title of object.
 
virtual UInt_t GetUniqueID () const
 Return the unique object id.
 
virtual Bool_t HandleTimer (TTimer *timer)
 Execute action in response of a timer timing out.
 
virtual ULong_t Hash () const
 Return hash value for this object.
 
Bool_t HasInconsistentHash () const
 Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.
 
virtual void Info (const char *method, const char *msgfmt,...) const
 Issue info message.
 
virtual Bool_t InheritsFrom (const char *classname) const
 Returns kTRUE if object inherits from class "classname".
 
virtual Bool_t InheritsFrom (const TClass *cl) const
 Returns kTRUE if object inherits from TClass cl.
 
virtual void Inspect () const
 Dump contents of this object in a graphics canvas.
 
void InvertBit (UInt_t f)
 
Bool_t IsDestructed () const
 IsDestructed.
 
virtual Bool_t IsEqual (const TObject *obj) const
 Default equal comparison (objects are equal if they have the same address in memory).
 
virtual Bool_t IsFolder () const
 Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).
 
R__ALWAYS_INLINE Bool_t IsOnHeap () const
 
virtual Bool_t IsSortable () const
 
R__ALWAYS_INLINE Bool_t IsZombie () const
 
virtual void ls (Option_t *option="") const
 The ls function lists the contents of a class on stdout.
 
void MayNotUse (const char *method) const
 Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).
 
void Obsolete (const char *method, const char *asOfVers, const char *removedFromVers) const
 Use this method to declare a method obsolete.
 
void operator delete (void *ptr)
 Operator delete.
 
void operator delete[] (void *ptr)
 Operator delete [].
 
void * operator new (size_t sz)
 
void * operator new (size_t sz, void *vp)
 
void * operator new[] (size_t sz)
 
void * operator new[] (size_t sz, void *vp)
 
TObjectoperator= (const TObject &rhs)
 TObject assignment operator.
 
virtual void Paint (Option_t *option="")
 This method must be overridden if a class wants to paint itself.
 
virtual void Pop ()
 Pop on object drawn in a pad to the top of the display list.
 
virtual void Print (Option_t *option="") const
 This method must be overridden when a class wants to print itself.
 
virtual Int_t Read (const char *name)
 Read contents of object with specified name from the current directory.
 
virtual void RecursiveRemove (TObject *obj)
 Recursively remove this object from a list.
 
void ResetBit (UInt_t f)
 
virtual void SaveAs (const char *filename="", Option_t *option="") const
 Save this object in the file specified by filename.
 
virtual void SavePrimitive (std::ostream &out, Option_t *option="")
 Save a primitive as a C++ statement(s) on output stream "out".
 
void SetBit (UInt_t f)
 
void SetBit (UInt_t f, Bool_t set)
 Set or unset the user status bits as specified in f.
 
virtual void SetDrawOption (Option_t *option="")
 Set drawing option for object.
 
virtual void SetUniqueID (UInt_t uid)
 Set the unique object id.
 
void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
 
virtual void SysError (const char *method, const char *msgfmt,...) const
 Issue system error message.
 
R__ALWAYS_INLINE Bool_t TestBit (UInt_t f) const
 
Int_t TestBits (UInt_t f) const
 
virtual void UseCurrentStyle ()
 Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.
 
virtual void Warning (const char *method, const char *msgfmt,...) const
 Issue warning message.
 
virtual Int_t Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0)
 Write this object to the current directory.
 
virtual Int_t Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const
 Write this object to the current directory.
 

Static Public Member Functions

static TClassClass ()
 
static const char * Class_Name ()
 
static constexpr Version_t Class_Version ()
 
static const char * DeclFileName ()
 
- Static Public Member Functions inherited from TNotifyLinkBase
static TClassClass ()
 
static const char * Class_Name ()
 
static constexpr Version_t Class_Version ()
 
static const char * DeclFileName ()
 
- Static Public Member Functions inherited from TObject
static TClassClass ()
 
static const char * Class_Name ()
 
static constexpr Version_t Class_Version ()
 
static const char * DeclFileName ()
 
static Longptr_t GetDtorOnly ()
 Return destructor only flag.
 
static Bool_t GetObjectStat ()
 Get status of object stat flag.
 
static void SetDtorOnly (void *obj)
 Set destructor only flag.
 
static void SetObjectStat (Bool_t stat)
 Turn on/off tracking of objects in the TObjectTable.
 

Private Attributes

Type * fSubscriber
 

Additional Inherited Members

- Public Types inherited from TNotifyLinkBase
enum  EStatusBits { kLinked = (1ULL << ( 11 )) }
 
- Public Types inherited from TObject
enum  {
  kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,
  kBitMask = 0x00ffffff
}
 
enum  { kSingleKey = (1ULL << ( 0 )) , kOverwrite = (1ULL << ( 1 )) , kWriteDelete = (1ULL << ( 2 )) }
 
enum  EDeprecatedStatusBits { kObjInCanvas = (1ULL << ( 3 )) }
 
enum  EStatusBits {
  kCanDelete = (1ULL << ( 0 )) , kMustCleanup = (1ULL << ( 3 )) , kIsReferenced = (1ULL << ( 4 )) , kHasUUID = (1ULL << ( 5 )) ,
  kCannotPick = (1ULL << ( 6 )) , kNoContextMenu = (1ULL << ( 8 )) , kInvalidObject = (1ULL << ( 13 ))
}
 
- Protected Types inherited from TObject
enum  { kOnlyPrepStep = (1ULL << ( 3 )) }
 
- Protected Member Functions inherited from TObject
virtual void DoError (int level, const char *location, const char *fmt, va_list va) const
 Interface to ErrorHandler (protected).
 
void MakeZombie ()
 
- Protected Attributes inherited from TNotifyLinkBase
TObjectfNext = nullptr
 Next node in a TChain's list of subscribers.
 
TNotifyLinkBasefPrevious = nullptr
 Previous node in a TChain's list of subscribers to its notification.
 

#include <TNotifyLink.h>

Inheritance diagram for TNotifyLink< Type >:
[legend]

Constructor & Destructor Documentation

◆ TNotifyLink()

template<class Type >
TNotifyLink< Type >::TNotifyLink ( Type *  subscriber)
inline

Definition at line 132 of file TNotifyLink.h.

Member Function Documentation

◆ Class()

template<class Type >
static TClass * TNotifyLink< Type >::Class ( )
static
Returns
TClass describing this class

◆ Class_Name()

template<class Type >
static const char * TNotifyLink< Type >::Class_Name ( )
static
Returns
Name of this class

◆ Class_Version()

template<class Type >
static constexpr Version_t TNotifyLink< Type >::Class_Version ( )
inlinestaticconstexpr
Returns
Version of this class

Definition at line 145 of file TNotifyLink.h.

◆ DeclFileName()

template<class Type >
static const char * TNotifyLink< Type >::DeclFileName ( )
inlinestatic
Returns
Name of the file containing the class declaration

Definition at line 145 of file TNotifyLink.h.

◆ IsA()

template<class Type >
TClass * TNotifyLink< Type >::IsA ( ) const
inlineoverridevirtual
Returns
TClass describing current object

Reimplemented from TObject.

Definition at line 145 of file TNotifyLink.h.

◆ Notify()

template<class Type >
Bool_t TNotifyLink< Type >::Notify ( )
inlineoverridevirtual

Call Notify on our subscriber and propagate the call to the next link.

Reimplemented from TObject.

Definition at line 135 of file TNotifyLink.h.

◆ Streamer()

template<class Type >
void TNotifyLink< Type >::Streamer ( TBuffer R__b)
overridevirtual

Stream an object of class TObject.

Reimplemented from TObject.

◆ StreamerNVirtual()

template<class Type >
void TNotifyLink< Type >::StreamerNVirtual ( TBuffer ClassDef_StreamerNVirtual_b)
inline

Definition at line 145 of file TNotifyLink.h.

Member Data Documentation

◆ fSubscriber

template<class Type >
Type* TNotifyLink< Type >::fSubscriber
private

Definition at line 129 of file TNotifyLink.h.

  • core/base/inc/TNotifyLink.h