TClonesArray Class Reference

An array of clone (identical) objects.

Memory for the objects stored in the array is allocated only once in the lifetime of the clones array. All objects must be of the same class. For the rest this class has the same properties as TObjArray.

To reduce the very large number of new and delete calls in large loops like this (O(100000) x O(10000) times new/delete):

TObjArray a(10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      a[i] = new TTrack(x,y,z,...);
      ...
      ...
   }
   ...
   a.Delete();
}

One better uses a TClonesArray which reduces the number of new/delete calls to only O(10000):

TClonesArray a("TTrack", 10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      new(a[i]) TTrack(x,y,z,...);
      ...
      ...
   }
   ...
   a.Delete(); // or a.Clear() or a.Clear("C")
}

To reduce the number of call to the constructor (especially useful if the user class requires memory allocation), the object can be added (and constructed when needed) using ConstructedAt which only calls the constructor once per slot.

TClonesArray a("TTrack", 10000);
while (TEvent *ev = (TEvent *)next()) {      // O(100000) events
   for (int i = 0; i < ev->Ntracks; i++) {   // O(10000) tracks
      TTrack *track = (TTrack*)a.ConstructedAt(i);
      track->Set(x,y,z,....);
      ...
      ...
   }
   ...
   a.Clear(); // or a.Clear("C");
}

Note: the only supported way to add objects to a TClonesArray is via the new with placement method or the ConstructedAt method. The other Add() methods ofTObjArray and its base classes are not allowed.

Considering that a new/delete costs about 70 mus on a 300 MHz HP, O(10^9) new/deletes will save about 19 hours.

NOTE 1

C/C++ offers the possibility of allocating and deleting memory. Forgetting to delete allocated memory is a programming error called a "memory leak", i.e. the memory of your process grows and eventually your program crashes. Even if you always delete the allocated memory, the recovered space may not be efficiently reused. The process knows that there are portions of free memory, but when you allocate it again, a fresh piece of memory is grabbed. Your program is free from semantic errors, but the total memory of your process still grows, because your program's memory is full of "holes" which reduce the efficiency of memory access; this is called "memory fragmentation". Moreover new / delete are expensive operations in terms of CPU time.

Without entering into technical details, TClonesArray allows you to "reuse" the same portion of memory for new/delete avoiding memory fragmentation and memory growth and improving the performance by orders of magnitude. Every time the memory of the TClonesArray has to be reused, the Clear() method is used. To provide its benefits, each TClonesArray must be allocated once per process and disposed of (deleted) only when not needed any more.

So a job should see only one deletion for each TClonesArray, which should be Clear()ed during the job several times. Deleting a TClonesArray is a double waste. Not only you do not avoid memory fragmentation, but you worsen it because the TClonesArray itself is a rather heavy structure, and there is quite some code in the destructor, so you have more memory fragmentation and slower code.

NOTE 2

When investigating misuse of TClonesArray, please make sure of the following:

• Use Clear() or Clear("C") instead of Delete(). This will improve program execution time.
• TClonesArray object classes containing pointers allocate memory. To avoid causing memory leaks, special Clear("C") must be used for clearing TClonesArray. When option "C" is specified, ROOT automatically executes the Clear() method (by default it is empty contained in TObject). This method must be overridden in the relevant TClonesArray object class, implementing the reset procedure for pointer objects.
• If the objects are added using the placement new then the Clear must deallocate the memory.
• If the objects are added using TClonesArray::ConstructedAt then the heap-based memory can stay allocated and reused as the constructor is not called for already constructed/added object.
• To reduce memory fragmentation, please make sure that the TClonesArrays are not destroyed and created on every event. They must only be constructed/destructed at the beginning/end of the run.

Definition at line 29 of file TClonesArray.h.

Public Types
enum	EStatusBits { kBypassStreamer = (1ULL << ( 12 )) , kForgetBits = (1ULL << ( 15 )) }
	Saved copies of pointers to objects. More...
Public Types inherited from TObjArray
typedef TObjArrayIter	Iterator_t
Public Types inherited from TCollection
enum	{ kInitCapacity = 16 , kInitHashTableCapacity = 17 }
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 )) }

Public Member Functions
	TClonesArray ()
	Default Constructor.
	TClonesArray (const char *classname, Int_t size=1000, Bool_t call_dtor=kFALSE)
	Create an array of clone objects of classname.
	TClonesArray (const TClass *cl, Int_t size=1000, Bool_t call_dtor=kFALSE)
	Create an array of clone objects of class cl.
	TClonesArray (const TClonesArray &tc)
	Copy ctor.
virtual	~TClonesArray ()
	Delete a clones array.
void	AbsorbObjects (TClonesArray *tc)
	Directly move the object pointers from tc without cloning (copying).
void	AbsorbObjects (TClonesArray *tc, Int_t idx1, Int_t idx2)
	Directly move the range of object pointers from tc without cloning (copying).
void	AddAfter (const TObject *, TObject *) override
void	AddAt (TObject *, Int_t) override
void	AddAtAndExpand (TObject *, Int_t) override
	Add object at position idx.
Int_t	AddAtFree (TObject *) override
	Return the position of the new object.
void	AddBefore (const TObject *, TObject *) override
void	AddFirst (TObject *) override
void	AddLast (TObject *) override
TObject *	AddrAt (Int_t idx)
void	BypassStreamer (Bool_t bypass=kTRUE)
	When the kBypassStreamer bit is set, the automatically generated Streamer can call directly TClass::WriteBuffer.
Bool_t	CanBypassStreamer () const
void	Clear (Option_t *option="") override
	Clear the clones array.
void	Compress () override
	Remove empty slots from array.
TObject *	ConstructedAt (Int_t idx)
	Get an object at index 'idx' that is guaranteed to have been constructed.
TObject *	ConstructedAt (Int_t idx, Option_t *clear_options)
	Get an object at index 'idx' that is guaranteed to have been constructed.
void	Delete (Option_t *option="") override
	Clear the clones array.
void	Expand (Int_t newSize) override
	Expand or shrink the array to newSize elements.
virtual void	ExpandCreate (Int_t n)
	Expand or shrink the array to n elements and create the clone objects by calling their default ctor.
virtual void	ExpandCreateFast (Int_t n)
	Expand or shrink the array to n elements and create the clone objects by calling their default ctor.
TClass *	GetClass () const
TClass *	IsA () const override
void	MultiSort (Int_t nTCs, TClonesArray **tcs, Int_t upto=kMaxInt)
	Sort multiple TClonesArrays simultaneously with this array.
TObject *	New (Int_t idx)
	Create an object of type fClass with the default ctor at the specified index.
TClonesArray &	operator= (const TClonesArray &tc)
	Assignment operator.
TObject *	operator[] (Int_t idx) const override
	Return the object at position idx. Returns 0 if idx is out of bounds.
TObject *&	operator[] (Int_t idx) override
	Return pointer to reserved area in which a new object of clones class can be constructed.
TObject *	Remove (TObject *obj) override
	Remove object from array.
TObject *	RemoveAt (Int_t idx) override
	Remove object at index idx.
void	RemoveRange (Int_t idx1, Int_t idx2) override
	Remove objects from index idx1 to idx2 included.
void	SetClass (const char *classname, Int_t size=1000)
	see TClonesArray::SetClass(const TClass*)
void	SetClass (const TClass *cl, Int_t size=1000)
	Create an array of clone objects of class cl.
void	SetOwner (Bool_t enable=kTRUE) override
	A TClonesArray is always the owner of the object it contains.
void	Sort (Int_t upto=kMaxInt) override
	If objects in array are sortable (i.e.
void	Streamer (TBuffer &) override
	Write all objects in array to the I/O buffer.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
Public Member Functions inherited from TObjArray
	TObjArray (const TObjArray &a)
	Create a copy of TObjArray a. Note, does not copy the kIsOwner flag.
	TObjArray (Int_t s=TCollection::kInitCapacity, Int_t lowerBound=0)
	Create an object array.
virtual	~TObjArray ()
	Delete an array.
void	Add (TObject *obj) override
void	AddAfter (const TObject *after, TObject *obj) override
	Add object in the slot after object after.
void	AddAt (TObject *obj, Int_t idx) override
	Add object at position ids.
void	AddBefore (const TObject *before, TObject *obj) override
	Add object in the slot before object before.
void	AddFirst (TObject *obj) override
	Add object in the first slot of the array.
void	AddLast (TObject *obj) override
	Add object in the next empty slot in the array.
TObject *	After (const TObject *obj) const override
	Return the object after obj. Returns 0 if obj is last object.
TObject *	At (Int_t idx) const override
TObject *	Before (const TObject *obj) const override
	Return the object before obj. Returns 0 if obj is first object.
virtual Int_t	BinarySearch (TObject *obj, Int_t upto=kMaxInt)
	Find object using a binary search.
void	Clear (Option_t *option="") override
	Remove all objects from the array.
void	Delete (Option_t *option="") override
	Remove all objects from the array AND delete all heap based objects.
TObject *	FindObject (const char *name) const override
	Find an object in this collection using its name.
TObject *	FindObject (const TObject *obj) const override
	Find an object in this collection using the object's IsEqual() member function.
TObject *	First () const override
	Return the object in the first slot.
Int_t	GetEntries () const override
	Return the number of objects in array (i.e.
Int_t	GetEntriesFast () const
Int_t	GetEntriesUnsafe () const
	Return the number of objects in array (i.e.
Int_t	GetLast () const override
	Return index of last object in array.
TObject **	GetObjectRef () const
TObject **	GetObjectRef (const TObject *obj) const override
	Return address of pointer obj. If obj is 0 returns address of container.
Int_t	IndexOf (const TObject *obj) const override
TClass *	IsA () const override
Bool_t	IsEmpty () const override
TObject *	Last () const override
	Return the object in the last filled slot. Returns 0 if no entries.
Int_t	LowerBound () const
TIterator *	MakeIterator (Bool_t dir=kIterForward) const override
	Returns an array iterator.
TObjArray &	operator= (const TObjArray &)
	Assignment operator. Note, unsets the kIsOwner flag.
virtual void	Randomize (Int_t ntimes=1)
	Randomize objects inside the array, i.e.
void	RecursiveRemove (TObject *obj) override
	Remove object from this collection and recursively remove the object from all other objects (and collections).
TObject *	Remove (TObject *obj) override
	Remove object from array.
TObject *	RemoveAt (Int_t idx) override
	Remove object at index idx.
void	SetLast (Int_t last)
	Set index of last object in array, effectively truncating the array.
void	Streamer (TBuffer &) override
	Stream all objects in the array to or from the I/O buffer.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
TObject *	UncheckedAt (Int_t i) const
Public Member Functions inherited from TSeqCollection
virtual	~TSeqCollection ()
void	Add (TObject *obj) override
TClass *	IsA () const override
virtual Bool_t	IsSorted () const
Int_t	LastIndex () const
Long64_t	Merge (TCollection *list)
	Merge this collection with all collections coming in the input list.
virtual void	RemoveAfter (TObject *after)
virtual void	RemoveBefore (TObject *before)
virtual void	RemoveFirst ()
virtual void	RemoveLast ()
void	Streamer (TBuffer &) override
	Stream all objects in the collection to or from the I/O buffer.
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
void	UnSort ()
Public Member Functions inherited from TCollection
virtual	~TCollection ()
	TNamed destructor.
virtual void	AddAll (const TCollection *col)
	Add all objects from collection col to this collection.
void	AddVector (TObject *obj1,...)
	Add all arguments to the collection.
Bool_t	AssertClass (TClass *cl) const
	Make sure all objects in this collection inherit from class cl.
TIter	begin () const
void	Browse (TBrowser *b) override
	Browse this collection (called by TBrowser).
Int_t	Capacity () const
TObject *	Clone (const char *newname="") const override
	Make a clone of an collection using the Streamer facility.
Int_t	Compare (const TObject *obj) const override
	Compare two TCollection objects.
Bool_t	Contains (const char *name) const
Bool_t	Contains (const TObject *obj) const
void	Draw (Option_t *option="") override
	Draw all objects in this collection.
void	Dump () const override
	Dump all objects in this collection.
TIter	end () const
const char *	GetName () const override
	Return name of this collection.
virtual Int_t	GetSize () const
	Return the capacity of the collection, i.e.
virtual Int_t	GrowBy (Int_t delta) const
	Increase the collection's capacity by delta slots.
ULong_t	Hash () const override
	Return hash value for this object.
Bool_t	IsArgNull (const char *where, const TObject *obj) const
	Returns true if object is a null pointer.
Bool_t	IsFolder () const override
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).
Bool_t	IsOwner () const
Bool_t	IsSortable () const override
R__ALWAYS_INLINE Bool_t	IsUsingRWLock () const
void	ls (Option_t *option="") const override
	List (ls) all objects in this collection.
virtual TIterator *	MakeReverseIterator () const
Bool_t	Notify () override
	'Notify' all objects in this collection.
TObject *	operator() (const char *name) const
	Find an object in this collection by name.
void	Paint (Option_t *option="") override
	Paint all objects in this collection.
virtual void	Print (Option_t *option, const char *wildcard, Int_t recurse=1) const
	Print the collection header and its elements that match the wildcard.
virtual void	Print (Option_t *option, Int_t recurse) const
	Print the collection header and its elements.
virtual void	Print (Option_t *option, TPRegexp &regexp, Int_t recurse=1) const
	Print the collection header and its elements that match the regexp.
void	Print (Option_t *option="") const override
	Default print for collections, calls Print(option, 1).
void	RemoveAll ()
virtual void	RemoveAll (TCollection *col)
	Remove all objects in collection col from this collection.
void	SetCurrentCollection ()
	Set this collection to be the globally accessible collection.
void	SetName (const char *name)
void	StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)
virtual bool	UseRWLock (Bool_t enable=true)
	Set this collection to use a RW lock upon access, making it thread safe.
Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) const override
	Write all objects in this collection.
Int_t	Write (const char *name=nullptr, Int_t option=0, Int_t bufsize=0) override
	Write all objects in this collection.
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.
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 void	Copy (TObject &object) const
	Copy this to obj.
virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object.
virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.
virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad with: gROOT->SetSelectedPad(c1).
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 Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.
virtual const char *	GetIconName () const
	Returns mime type 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_t *	GetOption () 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.
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).
R__ALWAYS_INLINE Bool_t	IsOnHeap () const
R__ALWAYS_INLINE Bool_t	IsZombie () const
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, void *vp)
	Only called by placement new when throwing an exception.
void	operator delete[] (void *ptr)
	Operator delete [].
void	operator delete[] (void *ptr, void *vp)
	Only called by placement new[] when throwing an exception.
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)
TObject &	operator= (const TObject &rhs)
	TObject assignment operator.
virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.
virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.
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.

Static Public Member Functions
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
Static Public Member Functions inherited from TObjArray
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
Static Public Member Functions inherited from TSeqCollection
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
static Int_t	ObjCompare (TObject *a, TObject *b)
	Compare to objects in the collection. Use member Compare() of object a.
static void	QSort (TObject **a, Int_t first, Int_t last)
	Sort array of TObject pointers using a quicksort algorithm.
static void	QSort (TObject **a, Int_t nBs, TObject ***b, Int_t first, Int_t last)
	Sort array a of TObject pointers using a quicksort algorithm.
static void	QSort (TObject **a, TObject **b, Int_t first, Int_t last)
Static Public Member Functions inherited from TCollection
static TClass *	Class ()
static const char *	Class_Name ()
static constexpr Version_t	Class_Version ()
static const char *	DeclFileName ()
static void	EmptyGarbageCollection ()
	Do the garbage collection.
static void	GarbageCollect (TObject *obj)
	Add to the list of things to be cleaned up.
static TCollection *	GetCurrentCollection ()
	Return the globally accessible collection.
static void	StartGarbageCollection ()
	Set up for garbage collection.
Static Public Member Functions inherited from TObject
static TClass *	Class ()
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.

Protected Attributes
TClass *	fClass
TObjArray *	fKeep
	Pointer to the class of the elements.
Protected Attributes inherited from TObjArray
TObject **	fCont
Int_t	fLast
Int_t	fLowerBound
	Array contents.
Protected Attributes inherited from TSeqCollection
Bool_t	fSorted
Protected Attributes inherited from TCollection
TString	fName
Int_t	fSize

Additional Inherited Members
Protected Types inherited from TCollection
enum	EStatusBits { kIsOwner = (1ULL << ( 14 )) , kUseRWLock = (1ULL << ( 16 )) }
Protected Types inherited from TObject
enum	{ kOnlyPrepStep = (1ULL << ( 3 )) }
Protected Member Functions inherited from TObjArray
Bool_t	BoundsOk (const char *where, Int_t at) const
Int_t	GetAbsLast () const
	Return absolute index to last object in array.
void	Init (Int_t s, Int_t lowerBound)
	Initialize a TObjArray.
Bool_t	OutOfBoundsError (const char *where, Int_t i) const
	Generate an out-of-bounds error. Always returns false.
Protected Member Functions inherited from TSeqCollection
	TSeqCollection ()
virtual void	Changed ()
Protected Member Functions inherited from TCollection
	TCollection ()
virtual const char *	GetCollectionEntryName (TObject *entry) const
	For given collection entry return the string that is used to identify the object and, potentially, perform wildcard/regexp filtering on.
virtual void	PrintCollectionEntry (TObject *entry, Option_t *option, Int_t recurse) const
	Print the collection entry.
virtual void	PrintCollectionHeader (Option_t *option) const
	Print the collection header.
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 ()

#include <TClonesArray.h>

Inheritance diagram for TClonesArray:

Member Enumeration Documentation

EStatusBits

enum TClonesArray::EStatusBits

Saved copies of pointers to objects.

Enumerator
kBypassStreamer
kForgetBits

Definition at line 36 of file TClonesArray.h.

Constructor & Destructor Documentation

TClonesArray() [1/4]

TClonesArray::TClonesArray

(

)

Default Constructor.

Definition at line 188 of file TClonesArray.cxx.

TClonesArray() [2/4]

TClonesArray::TClonesArray	(	const char *	classname,
		Int_t	s = 1000,
		Bool_t	call_dtor = kFALSE
	)

Create an array of clone objects of classname.

The class must inherit from TObject. The second argument s indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

The third argument is not used anymore and only there for backward compatibility reasons.

Definition at line 204 of file TClonesArray.cxx.

TClonesArray() [3/4]

TClonesArray::TClonesArray	(	const TClass *	cl,
		Int_t	s = 1000,
		Bool_t	call_dtor = kFALSE
	)

Create an array of clone objects of class cl.

The class must inherit from TObject. The second argument, s, indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

The third argument is not used anymore and only there for backward compatibility reasons.

Definition at line 220 of file TClonesArray.cxx.

TClonesArray() [4/4]

TClonesArray::TClonesArray

(

const TClonesArray &

tc

)

Copy ctor.

Definition at line 229 of file TClonesArray.cxx.

~TClonesArray()

TClonesArray::~TClonesArray ( )

virtual

Delete a clones array.

Definition at line 281 of file TClonesArray.cxx.

Member Function Documentation

AbsorbObjects() [1/2]

void TClonesArray::AbsorbObjects

(

TClonesArray *

tc

)

Directly move the object pointers from tc without cloning (copying).

This TClonesArray takes over ownership of all of tc's object pointers. The tc array is left empty upon return.

Definition at line 992 of file TClonesArray.cxx.

AbsorbObjects() [2/2]

void TClonesArray::AbsorbObjects	(	TClonesArray *	tc,
		Int_t	idx1,
		Int_t	idx2
	)

Directly move the range of object pointers from tc without cloning (copying).

This TClonesArray takes over ownership of all of tc's object pointers from idx1 to idx2. The tc array is re-arranged by return.

Definition at line 1005 of file TClonesArray.cxx.

AddAfter()

void TClonesArray::AddAfter ( const TObject *  , TObject *    )

inlineoverridevirtual

Implements TSeqCollection.

Definition at line 61 of file TClonesArray.h.

AddAt()

void TClonesArray::AddAt ( TObject *  , Int_t    )

inlineoverridevirtual

Implements TSeqCollection.

Definition at line 58 of file TClonesArray.h.

AddAtAndExpand()

void TClonesArray::AddAtAndExpand ( TObject *  obj, Int_t  idx  )

inlineoverridevirtual

Add object at position idx.

If idx is larger than the current size of the array, expand the array (double its size).

Reimplemented from TObjArray.

Definition at line 59 of file TClonesArray.h.

AddAtFree()

Int_t TClonesArray::AddAtFree ( TObject *  obj )

inlineoverridevirtual

Return the position of the new object.

Find the first empty cell or AddLast if there is no empty cell

Reimplemented from TObjArray.

Definition at line 60 of file TClonesArray.h.

AddBefore()

void TClonesArray::AddBefore ( const TObject *  , TObject *    )

inlineoverridevirtual

Implements TSeqCollection.

Definition at line 62 of file TClonesArray.h.

AddFirst()

void TClonesArray::AddFirst ( TObject *  )

inlineoverridevirtual

Implements TSeqCollection.

Definition at line 56 of file TClonesArray.h.

AddLast()

void TClonesArray::AddLast ( TObject *  )

inlineoverridevirtual

Implements TSeqCollection.

Definition at line 57 of file TClonesArray.h.

AddrAt()

TObject * TClonesArray::AddrAt ( Int_t  idx )

inline

Definition at line 86 of file TClonesArray.h.

BypassStreamer()

void TClonesArray::BypassStreamer

(

Bool_t

bypass = kTRUE

)

When the kBypassStreamer bit is set, the automatically generated Streamer can call directly TClass::WriteBuffer.

Bypassing the Streamer improves the performance when writing/reading the objects in the TClonesArray. However there is a drawback: When a TClonesArray is written with split=0 bypassing the Streamer, the StreamerInfo of the class in the array being optimized, one cannot use later the TClonesArray with split>0. For example, there is a problem with the following scenario:

1. A class Foo has a TClonesArray of Bar objects
2. The Foo object is written with split=0 to Tree T1. In this case the StreamerInfo for the class Bar is created in optimized mode in such a way that data members of the same type are written as an array improving the I/O performance.
3. In a new program, T1 is read and a new Tree T2 is created with the object Foo in split>1
4. When the T2 branch is created, the StreamerInfo for the class Bar is created with no optimization (mandatory for the split mode). The optimized Bar StreamerInfo is going to be used to read the TClonesArray in T1. The result will be Bar objects with data member values not in the right sequence. The solution to this problem is to call BypassStreamer(kFALSE) for the TClonesArray. In this case, the normal Bar::Streamer function will be called. The Bar::Streamer function works OK independently if the Bar StreamerInfo had been generated in optimized mode or not.

Definition at line 321 of file TClonesArray.cxx.

CanBypassStreamer()

Bool_t TClonesArray::CanBypassStreamer ( ) const

inline

Definition at line 64 of file TClonesArray.h.

Class()

static TClass * TClonesArray::Class ( )

static

Returns

TClass describing this class

Class_Name()

static const char * TClonesArray::Class_Name ( )

static

Returns

Name of this class

Class_Version()

static constexpr Version_t TClonesArray::Class_Version ( )

inlinestaticconstexpr

Returns

Version of this class

Definition at line 83 of file TClonesArray.h.

Clear()

void TClonesArray::Clear ( Option_t *  option = "" )

overridevirtual

Clear the clones array.

Only use this routine when your objects don't allocate memory since it will not call the object dtors. However, if the class in the TClonesArray implements the function Clear(Option_t *option) and if option = "C" the function Clear() is called for all objects in the array. In the function Clear(), one can delete objects or dynamic arrays allocated in the class. This procedure is much faster than calling TClonesArray::Delete(). When the option starts with "C+", eg "C+xyz" the objects in the array are in turn cleared with the option "xyz"

Implements TCollection.

Definition at line 420 of file TClonesArray.cxx.

Compress()

void TClonesArray::Compress ( )

overridevirtual

Remove empty slots from array.

Reimplemented from TObjArray.

Definition at line 332 of file TClonesArray.cxx.

ConstructedAt() [1/2]

TObject * TClonesArray::ConstructedAt

(

Int_t

idx

)

Get an object at index 'idx' that is guaranteed to have been constructed.

It might be either a freshly allocated object or one that had already been allocated (and assumingly used). In the later case, it is the callers responsibility to insure that the object is returned to a known state, usually by calling the Clear method on the TClonesArray.

Tests to see if the destructor has been called on the object. If so, or if the object has never been constructed the class constructor is called using New(). If not, return a pointer to the correct memory location. This explicitly to deal with TObject classes that allocate memory which will be reset (but not deallocated) in their Clear() functions.

Definition at line 377 of file TClonesArray.cxx.

ConstructedAt() [2/2]

TObject * TClonesArray::ConstructedAt	(	Int_t	idx,
		Option_t *	clear_options
	)

Get an object at index 'idx' that is guaranteed to have been constructed.

It might be either a freshly allocated object or one that had already been allocated (and assumingly used). In the later case, the function Clear will be called and passed the value of 'clear_options'

Tests to see if the destructor has been called on the object. If so, or if the object has never been constructed the class constructor is called using New(). If not, return a pointer to the correct memory location. This explicitly to deal with TObject classes that allocate memory which will be reset (but not deallocated) in their Clear() functions.

Definition at line 399 of file TClonesArray.cxx.

DeclFileName()

static const char * TClonesArray::DeclFileName ( )

inlinestatic

Returns

Name of the file containing the class declaration

Definition at line 83 of file TClonesArray.h.

Delete()

void TClonesArray::Delete ( Option_t *  option = "" )

overridevirtual

Clear the clones array.

Use this routine when your objects allocate memory (e.g. objects inheriting from TNamed or containing TStrings allocate memory). If not you better use Clear() since if is faster.

Implements TCollection.

Definition at line 452 of file TClonesArray.cxx.

Expand()

void TClonesArray::Expand ( Int_t  newSize )

overridevirtual

Expand or shrink the array to newSize elements.

Reimplemented from TObjArray.

Definition at line 480 of file TClonesArray.cxx.

ExpandCreate()

void TClonesArray::ExpandCreate ( Int_t  n )

virtual

Expand or shrink the array to n elements and create the clone objects by calling their default ctor.

If n is less than the current size the array is shrunk and the allocated space is freed. This routine is typically used to create a clonesarray into which one can directly copy object data without going via the "new (arr[i]) MyObj()" (i.e. the vtbl is already set correctly).

Definition at line 514 of file TClonesArray.cxx.

ExpandCreateFast()

void TClonesArray::ExpandCreateFast ( Int_t  n )

virtual

Expand or shrink the array to n elements and create the clone objects by calling their default ctor.

If n is less than the current size the array is shrunk but the allocated space is not freed. This routine is typically used to create a clonesarray into which one can directly copy object data without going via the "new (arr[i]) MyObj()" (i.e. the vtbl is already set correctly). This is a simplified version of ExpandCreate used in the TTree mechanism.

Definition at line 558 of file TClonesArray.cxx.

GetClass()

TClass * TClonesArray::GetClass ( ) const

inline

Definition at line 53 of file TClonesArray.h.

IsA()

TClass * TClonesArray::IsA ( ) const

inlineoverridevirtual

Returns

TClass describing current object

Reimplemented from TObject.

Definition at line 83 of file TClonesArray.h.

MultiSort()

void TClonesArray::MultiSort	(	Int_t	nTCs,
		TClonesArray **	tcs,
		Int_t	upto = kMaxInt
	)

Sort multiple TClonesArrays simultaneously with this array.

If objects in array are sortable (i.e. IsSortable() returns true for all objects) then sort array.

Definition at line 1061 of file TClonesArray.cxx.

New()

TObject * TClonesArray::New

(

Int_t

idx

)

Create an object of type fClass with the default ctor at the specified index.

Returns 0 in case of error.

Definition at line 968 of file TClonesArray.cxx.

operator=()

TClonesArray & TClonesArray::operator=

(

const TClonesArray &

tc

)

Assignment operator.

Definition at line 245 of file TClonesArray.cxx.

operator[]() [1/2]

TObject * TClonesArray::operator[] ( Int_t  idx ) const

overridevirtual

Return the object at position idx. Returns 0 if idx is out of bounds.

Reimplemented from TObjArray.

Definition at line 954 of file TClonesArray.cxx.

operator[]() [2/2]

TObject *& TClonesArray::operator[] ( Int_t  idx )

overridevirtual

Return pointer to reserved area in which a new object of clones class can be constructed.

This operator should not be used for lefthand side assignments, like a[2] = xxx. Only like, new (a[2]) myClass, or xxx = a[2]. Of course right hand side usage is only legal after the object has been constructed via the new operator or via the New() method. To remove elements from the clones array use Remove() or RemoveAt().

Reimplemented from TObjArray.

Definition at line 920 of file TClonesArray.cxx.

Remove()

TObject * TClonesArray::Remove ( TObject *  obj )

overridevirtual

Remove object from array.

Implements TCollection.

Definition at line 608 of file TClonesArray.cxx.

RemoveAt()

TObject * TClonesArray::RemoveAt ( Int_t  idx )

overridevirtual

Remove object at index idx.

Reimplemented from TSeqCollection.

Definition at line 584 of file TClonesArray.cxx.

RemoveRange()

void TClonesArray::RemoveRange ( Int_t  idx1, Int_t  idx2  )

overridevirtual

Remove objects from index idx1 to idx2 included.

Reimplemented from TObjArray.

Definition at line 631 of file TClonesArray.cxx.

SetClass() [1/2]

void TClonesArray::SetClass	(	const char *	classname,
		Int_t	size = 1000
	)

see TClonesArray::SetClass(const TClass*)

Definition at line 702 of file TClonesArray.cxx.

SetClass() [2/2]

void TClonesArray::SetClass	(	const TClass *	cl,
		Int_t	s = 1000
	)

Create an array of clone objects of class cl.

The class must inherit from TObject. The second argument s indicates an approximate number of objects that will be entered in the array. If more than s objects are entered, the array will be automatically expanded.

NB: This function should not be called in the TClonesArray is already initialized with a class.

Definition at line 665 of file TClonesArray.cxx.

SetOwner()

void TClonesArray::SetOwner ( Bool_t  enable = kTRUE )

overridevirtual

A TClonesArray is always the owner of the object it contains.

However the collection its inherits from (TObjArray) does not. Hence this member function needs to be a nop for TClonesArray.

Reimplemented from TCollection.

Definition at line 713 of file TClonesArray.cxx.

Sort()

void TClonesArray::Sort ( Int_t  upto = kMaxInt )

overridevirtual

If objects in array are sortable (i.e.

IsSortable() returns true for all objects) then sort array.

Reimplemented from TObjArray.

Definition at line 722 of file TClonesArray.cxx.

Streamer()

void TClonesArray::Streamer ( TBuffer &  b )

overridevirtual

Write all objects in array to the I/O buffer.

ATTENTION: empty slots are also stored (using one byte per slot). If you don't want this use a TOrdCollection or TList.

Reimplemented from TObject.

Definition at line 745 of file TClonesArray.cxx.

StreamerNVirtual()

void TClonesArray::StreamerNVirtual ( TBuffer &  ClassDef_StreamerNVirtual_b )

inline

Definition at line 83 of file TClonesArray.h.

Member Data Documentation

fClass

TClass* TClonesArray::fClass

protected

Definition at line 32 of file TClonesArray.h.

fKeep

TObjArray* TClonesArray::fKeep

protected

Pointer to the class of the elements.

Definition at line 33 of file TClonesArray.h.

Libraries for TClonesArray:

---

The documentation for this class was generated from the following files:

• core/cont/inc/TClonesArray.h
• core/cont/src/TClonesArray.cxx