ROOT logo
ROOT » CORE » META » TDataMember

class TDataMember: public TDictionary


 All ROOT classes may have RTTI (run time type identification) support
 added. The data is stored in so called DICTIONARY (look at TDictionary).
 Information about a class is stored in TClass.
 This information may be obtained via the CINT api - see class TCint.
 TClass has a list of TDataMember objects providing information about all
 data members of described class.

/* */
 TDataMember provides information about name of data member, its type,
 and comment field string. It also tries to find the TMethodCall objects
 responsible for getting/setting a value of it, and gives you pointers
 to these methods. This gives you a unique possibility to access
 protected and private (!) data members if only methods for doing that
 are defined.
 These methods could either be specified in a comment field, or found
 out automatically by ROOT: here's an example:
 suppose you have a class definition:

        class MyClass{
                Float_t fX1;
                void    SetX1(Float_t x) {fX1 = x;};
                Float_t GetX1()          {return fX1;};
 Look at the data member name and method names: a data member name has
 a prefix letter (f) and has a base name X1 . The methods for getting and
 setting this value have names which consist of string Get/Set and the
 same base name. This convention of naming data fields and methods which
 access them allows TDataMember find this methods by itself completely
 automatically. To make this description complete, one should know,
 that names that are automatically recognized may be also:
 for data fields: either fXXX or fIsXXX; and for getter function
 GetXXX() or IsXXX() [where XXX is base name].

 As an example of using it let's analyse a few lines which get and set
 a fEditable field in TCanvas:

    TCanvas     *c  = new TCanvas("c");   // create a canvas
    TClass      *cl = c->IsA();            // get its class description object.
    TDataMember *dm = cl->GetDataMember("fEditable"); //This is our data member
    TMethodCall *getter = dm->GetterMethod(c); //find a method that gets value!
    Long_t l;   // declare a storage for this value;
    getter->Execute(c,"",l);  // Get this Value !!!! It will appear in l !!!
    TMethodCall *setter = dm->SetterMethod(c);
    setter->Execute(c,"0",);   // Set Value 0 !!!

 This trick is widely used in ROOT TContextMenu and dialogs for obtaining
 current values and put them as initial values in dialog fields.

 If you don't want to follow the convention of naming used by ROOT
 you still could benefit from Getter/Setter method support: the solution
 is to instruct ROOT what the names of these routines are.
 The way to do it is putting this information in a comment string to a data
 field in your class declaration:

    class MyClass{
        Int_t mydata;  //  *OPTIONS={GetMethod="Get";SetMethod="Set"} 
        Int_t Get() const { return mydata;};
        void  Set(Int_t i) {mydata=i;};

 However, this getting/setting functions are not the only feature of
 this class. The next point is providing lists of possible settings
 for the concerned data member. The idea is to have a list of possible
 options for this data member, with strings identifying them. This
 is used in dialogs with parameters to set - for details see
 TMethodArg, TRootContextMenu, TContextMenu. This list not only specifies
 the allowed value, but also provides strings naming the options.
 Options are managed via TList of TOptionListItem objects. This list
 is also  created automatically: if a data type is an enum tynpe,
 the list will have items describing every enum value, and named
 according to enum name. If type is Bool_t, two options "On" and "Off"
 with values 0 and 1 are created. For other types you need to instruct
 ROOT about possible options. The way to do it is the same as in case of
 specifying getter/setter method: a comment string to a data field in
 Your header file with class definition.
 The most general format of this string is:

*OPTIONS={GetMethod="getter";SetMethod="setter";Items=(it1="title1",it2="title2", ... ) } 

 While parsing this string ROOT firstly looks for command-tokens:
 GetMethod, SetMethod, Items; They must be preceded by string
 *OPTIONS= , enclosed by {} and separated by semicolons ";".
 All command token should have a form TOKEN=VALUE.
 All tokens are optional.
 The names of getter and setter method must be enclosed by double-quote
 marks (") .
 Specifications of Items is slightly more complicated: you need to
 put token ITEMS= and then enclose all options in curly brackets "()".
 You separate options by comas ",".
 Each option item may have one of the following forms:

         IntegerValue  = "Text Label"
         EnumValue     = "Text Label"
        "TextValue" = Text Label"

 One can sepcify values as Integers or Enums - when data field is an
 Integer, Float or Enum type; as texts - for char (more precisely:

 As mentioned above - this information are mainly used by contextmenu,
 but also in Dump() and Inspect() methods and by the THtml class.

Function Members (Methods)

TDataMember(DataMemberInfo_t* info = 0, TClass* cl = 0)
voidTObject::AbstractMethod(const char* method) const
virtual voidTObject::AppendPad(Option_t* option = "")
virtual voidTObject::Browse(TBrowser* b)
static TClass*Class()
virtual const char*TObject::ClassName() const
virtual voidTNamed::Clear(Option_t* option = "")
virtual TObject*TNamed::Clone(const char* newname = "") const
virtual Int_tTNamed::Compare(const TObject* obj) const
virtual voidTNamed::Copy(TObject& named) const
virtual voidTObject::Delete(Option_t* option = "")MENU
virtual Int_tTObject::DistancetoPrimitive(Int_t px, Int_t py)
virtual voidTObject::Draw(Option_t* option = "")
virtual voidTObject::DrawClass() constMENU
virtual TObject*TObject::DrawClone(Option_t* option = "") constMENU
virtual voidTObject::Dump() constMENU
virtual voidTObject::Error(const char* method, const char* msgfmt) const
virtual voidTObject::Execute(const char* method, const char* params, Int_t* error = 0)
virtual voidTObject::Execute(TMethod* method, TObjArray* params, Int_t* error = 0)
virtual voidTObject::ExecuteEvent(Int_t event, Int_t px, Int_t py)
virtual voidTObject::Fatal(const char* method, const char* msgfmt) const
virtual voidTNamed::FillBuffer(char*& buffer)
virtual TObject*TObject::FindObject(const char* name) const
virtual TObject*TObject::FindObject(const TObject* obj) const
Int_tGetArrayDim() const
const char*GetArrayIndex() const
TClass*GetClass() const
TDataType*GetDataType() const
static TDictionary*TDictionary::GetDictionary(const char* name)
static TDictionary*TDictionary::GetDictionary(const type_info& typeinfo)
virtual Option_t*TObject::GetDrawOption() const
static Long_tTObject::GetDtorOnly()
const char*GetFullTypeName() const
virtual const char*TObject::GetIconName() const
Int_tGetMaxIndex(Int_t dim) const
virtual const char*TNamed::GetName() const
virtual char*TObject::GetObjectInfo(Int_t px, Int_t py) const
static Bool_tTObject::GetObjectStat()
Long_tGetOffset() const
Long_tGetOffsetCint() const
virtual Option_t*TObject::GetOption() const
TList*GetOptions() const
TMethodCall*GetterMethod(TClass* cl = 0)
virtual const char*TNamed::GetTitle() const
const char*GetTrueTypeName() const
const char*GetTypeName() const
virtual UInt_tTObject::GetUniqueID() const
Int_tGetUnitSize() const
virtual Bool_tTObject::HandleTimer(TTimer* timer)
virtual ULong_tTNamed::Hash() const
virtual voidTObject::Info(const char* method, const char* msgfmt) const
virtual Bool_tTObject::InheritsFrom(const char* classname) const
virtual Bool_tTObject::InheritsFrom(const TClass* cl) const
virtual voidTObject::Inspect() constMENU
voidTObject::InvertBit(UInt_t f)
virtual TClass*IsA() const
Bool_tIsaPointer() const
Bool_tIsBasic() const
Bool_tIsEnum() const
virtual Bool_tTObject::IsEqual(const TObject* obj) const
virtual Bool_tTObject::IsFolder() const
Bool_tTObject::IsOnHeap() const
Bool_tIsPersistent() const
virtual Bool_tTNamed::IsSortable() const
Bool_tTObject::IsZombie() const
virtual voidTNamed::ls(Option_t* option = "") const
voidTObject::MayNotUse(const char* method) const
virtual Bool_tTObject::Notify()
voidTObject::Obsolete(const char* method, const char* asOfVers, const char* removedFromVers) const
static voidTObject::operator delete(void* ptr)
static voidTObject::operator delete(void* ptr, void* vp)
static voidTObject::operator delete[](void* ptr)
static voidTObject::operator delete[](void* ptr, void* vp)
void*TObject::operator new(size_t sz)
void*TObject::operator new(size_t sz, void* vp)
void*TObject::operator new[](size_t sz)
void*TObject::operator new[](size_t sz, void* vp)
virtual voidTObject::Paint(Option_t* option = "")
virtual voidTObject::Pop()
virtual voidTNamed::Print(Option_t* option = "") const
virtual Long_tProperty() const
virtual Int_tTObject::Read(const char* name)
virtual voidTObject::RecursiveRemove(TObject* obj)
voidTObject::ResetBit(UInt_t f)
virtual voidTObject::SaveAs(const char* filename = "", Option_t* option = "") constMENU
virtual voidTObject::SavePrimitive(ostream& out, Option_t* option = "")
voidTObject::SetBit(UInt_t f)
voidTObject::SetBit(UInt_t f, Bool_t set)
virtual voidTObject::SetDrawOption(Option_t* option = "")MENU
static voidTObject::SetDtorOnly(void* obj)
virtual voidTNamed::SetName(const char* name)MENU
virtual voidTNamed::SetNameTitle(const char* name, const char* title)
static voidTObject::SetObjectStat(Bool_t stat)
TMethodCall*SetterMethod(TClass* cl)
virtual voidTNamed::SetTitle(const char* title = "")MENU
virtual voidTObject::SetUniqueID(UInt_t uid)
virtual voidShowMembers(TMemberInspector& insp)
virtual Int_tTNamed::Sizeof() const
virtual voidStreamer(TBuffer& b)
voidStreamerNVirtual(TBuffer& b)
virtual voidTObject::SysError(const char* method, const char* msgfmt) const
Bool_tTObject::TestBit(UInt_t f) const
Int_tTObject::TestBits(UInt_t f) const
virtual voidTObject::UseCurrentStyle()
virtual voidTObject::Warning(const char* method, const char* msgfmt) const
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0)
virtual Int_tTObject::Write(const char* name = 0, Int_t option = 0, Int_t bufsize = 0) const
TDataMember(const TDataMember&)
virtual voidTObject::DoError(int level, const char* location, const char* fmt, va_list va) const
TDataMember&operator=(const TDataMember&)

Data Members

enum { kObjIsPersistent
enum TDictionary::ESTLType { kNone
enum TObject::EStatusBits { kCanDelete
enum TObject::[unnamed] { kIsOnHeap
TStringTNamed::fNameobject identifier
TStringTNamed::fTitleobject title
TClass*fClasspointer to the class
TDataType*fDataTypepointer to data basic type descriptor
TStringfFullTypeNamefull type description of data member, e,g.: "class TDirectory*".
DataMemberInfo_t*fInfopointer to CINT data member info
TList*fOptionslist of possible values 0=no restrictions
Int_tfSTLContSTL type
TStringfTrueTypeNamefull type description with no typedef
TStringfTypeNamedata member type, e,g.: "class TDirectory*" -> "TDirectory".
TMethodCall*fValueGettermethod that returns a value;
TMethodCall*fValueSettermethod which sets value;

Class Charts

Inheritance Inherited Members Includes Libraries
Class Charts

Function documentation

TDataMember(DataMemberInfo_t* info = 0, TClass* cl = 0)
 Default TDataMember ctor. TDataMembers are constructed in TClass
 via a call to TCint::CreateListOfDataMembers(). It parses the comment
 string, initializes optionlist and getter/setter methods.
TDataMember(const TDataMember& )
copy constructor
TDataMember& operator=(const TDataMember& )
assignement operator
 TDataMember dtor deletes adopted CINT DataMemberInfo object.
Int_t GetArrayDim() const
 Return number of array dimensions.
const char * GetArrayIndex() const
 If the data member is pointer and has a valid array size in its comments
 GetArrayIndex returns a string pointing to it;
 otherwise it returns an empty string.
Int_t GetMaxIndex(Int_t dim) const
 Return maximum index for array dimension "dim".
const char * GetTypeName() const
 Get type of data member, e,g.: "class TDirectory*" -> "TDirectory".
const char * GetFullTypeName() const
 Get full type description of data member, e,g.: "class TDirectory*".
const char * GetTrueTypeName() const
 Get full type description of data member, e,g.: "class TDirectory*".
Long_t GetOffset() const
 Get offset from "this".
Long_t GetOffsetCint() const
 Get offset from "this" using the information in CINT only.
Int_t GetUnitSize() const
 Get the sizeof the underlying type of the data member
 (i.e. if the member is an array sizeof(member)/length)
Bool_t IsBasic() const
 Return true if data member is a basic type, e.g. char, int, long...
Bool_t IsEnum() const
 Return true if data member is an enum.
Bool_t IsaPointer() const
 Return true if data member is a pointer.
int IsSTLContainer()
 The return type is defined in TDictionary (kVector, kList, etc.)
Long_t Property() const
 Get property description word. For meaning of bits see EProperty.
TList * GetOptions() const
 Returns list of options - list of TOptionListItems
TMethodCall * GetterMethod(TClass* cl = 0)
 Return a TMethodCall method responsible for getting the value
 of data member. The cl argument specifies the class of the object
 which will be used to call this method (in case of multiple
 inheritance TMethodCall needs to know this to calculate the proper
TMethodCall * SetterMethod(TClass* cl)
 Return a TMethodCall method responsible for setting the value
 of data member. The cl argument specifies the class of the object
 which will be used to call this method (in case of multiple
 inheritance TMethodCall needs to know this to calculate the proper
TClass * GetClass() const
{ return fClass; }
TDataType * GetDataType() const
{ return fDataType; }
Bool_t IsPersistent() const