A TFolder object is a collection of objects and folders.

Folders have a name and a title and are identified in the folder hierarchy by a "Unix-like" naming mechanism. The root of all folders is //root. New folders can be dynamically added or removed to/from a folder. The folder hierarchy can be visualized via the TBrowser.

The Root folders hierarchy can be seen as a whiteboard where objects are posted. Other classes/tasks can access these objects by specifying only a string pathname. This whiteboard facility greatly improves the modularity of an application, minimizing the class relationship problem that penalizes large applications.

Pointers are efficient to communicate between classes. However, one has interest to minimize direct coupling between classes in the form of direct pointers. One better uses the naming and search service provided by the Root folders hierarchy. This makes the classes loosely coupled and also greatly facilitates I/O operations. In a client/server environment, this mechanism facilitates the access to any kind of object in //root stores running on different processes.

A TFolder is created by invoking the TFolder constructor. It is placed inside an existing folder via the TFolder::AddFolder method. One can search for a folder or an object in a folder using the FindObject method. FindObject analyses the string passed as its argument and searches in the hierarchy until it finds an object or folder matching the name.

When a folder is deleted, its reference from the parent folder and possible other folders is deleted.

If a folder has been declared the owner of its objects/folders via TFolder::SetOwner, then the contained objects are deleted when the folder is deleted. By default, a folder does not own its contained objects.

NOTE that folder ownership can be set

via TFolder::SetOwner
or via TCollection::SetOwner on the collection specified to TFolder::AddFolder

Standard Root objects are automatically added to the folder hierarchy. For example, the following folders exist: root/Files with the list of currently connected Root files root/Classes with the list of active classes root/Geometries with active geometries root/Canvases with the list of active canvases root/Styles with the list of graphics styles root/Colors with the list of active colors

For example, if a file "myFile.root" is added to the list of files, one can retrieve a pointer to the corresponding TFile object with a statement like:

TFile *myFile = (TFile*)gROOT->FindObject("//root/Files/myFile.root");

gROOT

#define gROOT

Definition TROOT.h:404

TDirectory::FindObject

TObject * FindObject(const char *name) const override

Find object by name in the list of memory objects.

Definition TDirectory.cxx:779

TFile

A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.

Definition TFile.h:54

The above statement can be abbreviated to:

TFile *myFile = (TFile*)gROOT->FindObject("/Files/myFile.root");

or even to:

TFile *myFile = (TFile*)gROOT->FindObjectAny("myFile.root");

TDirectoryFile::FindObjectAny

TObject * FindObjectAny(const char *name) const override

Find object by name in the list of memory objects of the current directory or its sub-directories.

Definition TDirectoryFile.cxx:843

In this last case, the TROOT::FindObjectAny function will scan the folder hierarchy starting at //root and will return the first object named "myFile.root".

Because a string-based search mechanism is expensive, it is recommended to save the pointer to the object as a class member or local variable if this pointer is used frequently or inside loops.

Definition at line 30 of file TFolder.h.

Public Member Functions
	TFolder ()
	Default constructor used by the Input functions.

	TFolder (const char name, const char title)
	Create a normal folder.

virtual	~TFolder ()
	Folder destructor.

virtual void	Add (TObject *obj)
	Add object to this folder. obj must be a TObject or a TFolder.

TFolder *	AddFolder (const char name, const char title, TCollection *collection=0)
	Create a new folder and add it to the list of folders of this folder, return a pointer to the created folder.

virtual void	Browse (TBrowser *b)
	Browse this folder.

virtual void	Clear (Option_t *option="")
	Delete all objects from a folder list.

virtual void	Copy (TObject &) const
	Copy this to obj.

virtual const char *	FindFullPathName (const char *name) const
	Return the full pathname corresponding to subpath name if the node is gROOT->GetRootFolder() and return a relative path otherwise.

virtual const char *	FindFullPathName (const TObject *obj) const
	Return the full pathname corresponding to subpath name.

virtual TObject *	FindObject (const char *name) const
	Search object identified by name in the tree of folders inside this folder.

virtual TObject *	FindObject (const TObject *obj) const
	Find object in an folder.

virtual TObject *	FindObjectAny (const char *name) const
	Return a pointer to the first object with name starting at this folder.

TCollection *	GetListOfFolders () const

Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).

Bool_t	IsOwner () const
	Folder ownership has been set via.

virtual void	ls (Option_t *option="") const
	List folder contents.

virtual Int_t	Occurence (const TObject *obj) const
	Return occurence number of object in the list of objects of this folder.

virtual void	RecursiveRemove (TObject *obj)
	Recursively remove object from a folder.

virtual void	Remove (TObject *obj)
	Remove object from this folder. obj must be a TObject or a TFolder.

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save all objects in this folder in filename.

virtual void	SetOwner (Bool_t owner=kTRUE)
	Set ownership.

Public Member Functions inherited from TNamed
	TNamed ()

	TNamed (const char name, const char title)

	TNamed (const TNamed &named)
	TNamed copy ctor.

	TNamed (const TString &name, const TString &title)

virtual	~TNamed ()
	TNamed destructor.

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility.

virtual Int_t	Compare (const TObject *obj) const
	Compare two TNamed objects.

virtual void	FillBuffer (char *&buffer)
	Encode TNamed into output buffer.

virtual const char *	GetName () const
	Returns name of object.

virtual const char *	GetTitle () const
	Returns title of object.

virtual ULong_t	Hash () const
	Return hash value for this object.

virtual Bool_t	IsSortable () const

TNamed &	operator= (const TNamed &rhs)
	TNamed assignment operator.

virtual void	Print (Option_t *option="") const
	Print TNamed name and title.

virtual void	SetName (const char *name)
	Set the name of the TNamed.

virtual void	SetNameTitle (const char name, const char title)
	Set all the TNamed parameters (name and title).

virtual void	SetTitle (const char *title="")
	Set the title of the TNamed.

virtual Int_t	Sizeof () const
	Return size of the TNamed part of the TObject.

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	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 TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: `gROOT->SetSelectedPad(gPad)`.

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=0)
	Execute method on this object with the given parameter string, e.g.

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	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 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).

virtual Bool_t	Notify ()
	This method must be overridden to handle object notification.

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)

TObject &	operator= (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 Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.

void	ResetBit (UInt_t f)

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.

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=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.

Protected Attributes
TCollection *	fFolders

Bool_t	fIsOwner

Protected Attributes inherited from TNamed
TString	fName

TString	fTitle

Private Member Functions
	TFolder (const TFolder &folder)
	Copy constructor.

void	operator= (const TFolder &)

Additional Inherited Members
Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 , kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }

enum	EDeprecatedStatusBits { kObjInCanvas = BIT(3) }

enum	EStatusBits { kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) , kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13) }

Static Public Member Functions inherited from TObject
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 Types inherited from TObject
enum	{ kOnlyPrepStep = BIT(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 ()

#include <TFolder.h>

Inheritance diagram for TFolder:

[legend]

Constructor & Destructor Documentation

◆ TFolder() [1/3]

TFolder::TFolder ( const TFolder & folder )

private

Copy constructor.

Definition at line 130 of file TFolder.cxx.

◆ TFolder() [2/3]

TFolder::TFolder ( )

Default constructor used by the Input functions.

This constructor should not be called by a user directly. The normal way to create a folder is by calling TFolder::AddFolder.

Definition at line 110 of file TFolder.cxx.

◆ TFolder() [3/3]

TFolder::TFolder	(	const char *	name,
		const char *	title
	)

Create a normal folder.

Use Add or AddFolder to add objects or folders to this folder.

Definition at line 120 of file TFolder.cxx.

◆ ~TFolder()

TFolder::~TFolder ( )

virtual

Folder destructor.

Remove all objects from its lists and delete all its sub folders.

Definition at line 139 of file TFolder.cxx.

Member Function Documentation

◆ Add()

void TFolder::Add ( TObject * obj )

virtual

Add object to this folder. obj must be a TObject or a TFolder.

Definition at line 172 of file TFolder.cxx.

◆ AddFolder()

TFolder * TFolder::AddFolder	(	const char *	name,
		const char *	title,
		TCollection *	collection = `0`
	)

Create a new folder and add it to the list of folders of this folder, return a pointer to the created folder.

Note that a folder can be added to several folders.

If collection is non NULL, the pointer fFolders is set to the existing collection, otherwise a default collection (Tlist) is created. Note that the folder name cannot contain slashes.

Definition at line 188 of file TFolder.cxx.

◆ Browse()

void TFolder::Browse ( TBrowser * b )

virtual

Browse this folder.

Reimplemented from TObject.

Definition at line 219 of file TFolder.cxx.

◆ Clear()

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

virtual

Delete all objects from a folder list.

Reimplemented from TNamed.

Definition at line 227 of file TFolder.cxx.

◆ Copy()

virtual void TFolder::Copy ( TObject & named ) const

inlinevirtual

Copy this to obj.

Reimplemented from TNamed.

Definition at line 49 of file TFolder.h.

◆ FindFullPathName() [1/2]

const char * TFolder::FindFullPathName ( const char * name ) const

virtual

Return the full pathname corresponding to subpath name if the node is gROOT->GetRootFolder() and return a relative path otherwise.

The returned path will be re-used by the next call to FindFullPathName().

Definition at line 237 of file TFolder.cxx.

◆ FindFullPathName() [2/2]

const char * TFolder::FindFullPathName ( const TObject * obj ) const

virtual

Return the full pathname corresponding to subpath name.

The returned path will be re-used by the next call to FindFullPathName().

Definition at line 282 of file TFolder.cxx.

◆ FindObject() [1/2]

TObject * TFolder::FindObject ( const char * name ) const

virtual

Search object identified by name in the tree of folders inside this folder.

Name may be of the forms:

A. Specify a full pathname starting at the top ROOT folder //root/xxx/yyy/name

B. Specify a pathname starting with a single slash. //root is assumed /xxx/yyy/name

C. Specify a pathname relative to this folder xxx/yyy/name name

Reimplemented from TObject.

Definition at line 312 of file TFolder.cxx.

◆ FindObject() [2/2]

TObject * TFolder::FindObject ( const TObject * obj ) const

virtual

Find object in an folder.

Reimplemented from TObject.

Definition at line 291 of file TFolder.cxx.

◆ FindObjectAny()

TObject * TFolder::FindObjectAny ( const char * name ) const

virtual

Return a pointer to the first object with name starting at this folder.

Definition at line 349 of file TFolder.cxx.

◆ GetListOfFolders()

TCollection * TFolder::GetListOfFolders ( ) const

inline

Definition at line 55 of file TFolder.h.

◆ IsFolder()

Bool_t TFolder::IsFolder ( ) const

inlinevirtual

Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).

Reimplemented from TObject.

Definition at line 56 of file TFolder.h.

◆ IsOwner()

Bool_t TFolder::IsOwner ( ) const

Folder ownership has been set via.

TFolder::SetOwner
TCollection::SetOwner on the collection specified to TFolder::AddFolder

Definition at line 375 of file TFolder.cxx.

◆ ls()

void TFolder::ls ( Option_t * option = "" ) const

virtual

List folder contents.

If option contains "dump", the Dump function of contained objects is called.

If option contains "print", the Print function of contained objects is called.

By default the ls function of contained objects is called.

Indentation is used to identify the folder tree.

The if option contains a <regexp> it be used to match the name of the objects.

Reimplemented from TNamed.

Definition at line 394 of file TFolder.cxx.

◆ Occurence()

Int_t TFolder::Occurence ( const TObject * object ) const

virtual

Return occurence number of object in the list of objects of this folder.

The function returns the number of objects with the same name as object found in the list of objects in this folder before object itself. If only one object is found, return 0.

Definition at line 433 of file TFolder.cxx.

◆ operator=()

void TFolder::operator= ( const TFolder & )

private

◆ RecursiveRemove()

void TFolder::RecursiveRemove ( TObject * obj )

virtual

Recursively remove object from a folder.

Reimplemented from TObject.

Definition at line 455 of file TFolder.cxx.

◆ Remove()

void TFolder::Remove ( TObject * obj )

virtual

Remove object from this folder. obj must be a TObject or a TFolder.

Definition at line 463 of file TFolder.cxx.

◆ SaveAs()

void TFolder::SaveAs	(	const char *	filename = `""`,
		Option_t *	option = `""`
	)		const

virtual

Save all objects in this folder in filename.

Each object in this folder will have a key in the file where the name of the key will be the name of the object.

Reimplemented from TObject.

Definition at line 474 of file TFolder.cxx.

◆ SetOwner()

void TFolder::SetOwner ( Bool_t owner = kTRUE )

virtual

Set ownership.

If the folder is declared owner, when the folder is deleted, all the objects added via TFolder::Add are deleted via TObject::Delete, otherwise TObject::Clear is called.

NOTE that folder ownership can be set:

via TFolder::SetOwner
or via TCollection::SetOwner on the collection specified to TFolder::AddFolder

Definition at line 489 of file TFolder.cxx.

Member Data Documentation

◆ fFolders

TCollection* TFolder::fFolders

protected

Definition at line 33 of file TFolder.h.

◆ fIsOwner

Bool_t TFolder::fIsOwner

protected

Definition at line 34 of file TFolder.h.

core/base/inc/TFolder.h

core/base/src/TFolder.cxx

Public Member Functions

Protected Attributes

Private Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ TFolder() [1/3]

◆ TFolder() [2/3]

◆ TFolder() [3/3]

◆ ~TFolder()

Member Function Documentation

◆ Add()

◆ AddFolder()

◆ Browse()

◆ Clear()

◆ Copy()

◆ FindFullPathName() [1/2]

◆ FindFullPathName() [2/2]

◆ FindObject() [1/2]

◆ FindObject() [2/2]

◆ FindObjectAny()

◆ GetListOfFolders()

◆ IsFolder()

◆ IsOwner()

◆ ls()

◆ Occurence()

◆ operator=()

◆ RecursiveRemove()

◆ Remove()

◆ SaveAs()

◆ SetOwner()

Member Data Documentation

◆ fFolders

◆ fIsOwner