[ROOT] TObject user bits

From: Frankland John (frankland@ganil.fr)
Date: Fri Sep 19 2003 - 17:05:27 MEST 

Hi ROOT-fiends

I'm having some trouble understanding the so-called "user bits" in TObject.
I would like to have a TObject-derived object in which I use the 
existing bits as
flags rather than adding extra member variables, like this:

class BitClass : public TObject
{
public:
    SetOn() { SetBit(0); };
    SetOff() { ResetBit(0); };
    GetStatus() { return TestBit(0); };
}

The question is : which bit numbers can I use with Set/Test/ResetBit ?
According to the TObject ctor doc "the high 8 bits are reserved for 
system usage and the low 24 bits are user settable".
But in TObject.h I see

//----- Global bits (can be set for any object and should not be reused).
//----- Bits 0 - 13 are reserved as global bits. Bits 14 - 23 can be used
//----- in different class hierarchies (make sure there is no overlap in
//----- any given hierarchy).

D'ou slight confusion in my head. Sorry if this is trivial, but I have 
another "bit" question:
which are the "high 8 bits" ? SetBit(0) through to SetBit(7) or 
SetBit(25) through to SetBit(32) ?

Thanks a lot
John
-- 

John D. Frankland <mailto:frankland@ganil.fr>
Beam Coordinator
GANIL
B.P. 55027
14076 CAEN Cedex 05

*tel:* +33 (0)231454628
*fax:* +33 (0)231454665

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