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TGeoExtension.cxx
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1 // Author: Andrei.Gheata@cern.ch 29/05/2013
2 // Following proposal by Markus Frank
3 
4 /*************************************************************************
5  * Copyright (C) 1995-2000, Rene Brun and Fons Rademakers. *
6  * All rights reserved. *
7  * *
8  * For the licensing terms see $ROOTSYS/LICENSE. *
9  * For the list of contributors see $ROOTSYS/README/CREDITS. *
10  *************************************************************************/
11 
12 #include "TGeoExtension.h"
13 
14 #include "Rtypes.h"
15 
17 
18 /** \class TGeoExtension
19 \ingroup Geometry_classes
20 
21 ABC for user objects attached to TGeoVolume or TGeoNode.
22 Provides interface for getting a reference (grab) and
23 releasing the extension object (release), allowing for
24 derived classes to implement reference counted sharing.
25 The user who should attach extensions to logical volumes
26 or nodes BEFORE applying misalignment information so that
27 these will be available to all copies.
28 */
29 
31 
32 /** \class TGeoRCExtension
33 \ingroup Geometry_classes
34 
35 Reference counted extension which has a pointer to and
36 owns a user defined TObject. This class can be used as
37 model for a reference counted derivation from TGeoExtension.
38 
39 Note: Creating a TGeoRCExtension with new() automatically grabs it, but the
40 creator has to Release it before the pointer gets out of scope.
41 The following sequence is valid:
42 
43 ~~~ {.cpp}
44  // producer:
45  TGeoRCExtension *ext = new TGeoRCExtension();
46  some_TGeoVolume->SetUserExtension(ext);
47  ext->Release();
48  // user:
49  TGeoRCExtension *ext = dynamic_cast<TGeoRCExtension*>(some_TGeoVolume->GrabUserExtension());
50  // ... use extension
51  ext->Release();
52 ~~~
53 
54 The extension is going to be released by the TGeoVolume holder at the destruction
55 or when calling SetUserExtension(0).
56 
57 The following usage is not correct:
58 
59 ~~~ {.cpp}
60  some_TGeoVolume->SetUserExtension(new TGeoRCExtension())
61 ~~~
62 
63 since the producer code does not release the extension.
64 One cannot call directly "delete ext" nor allocate an extension on the stack,
65 since the destructor is protected. Use Release instead.
66 */
ClassImp
#define ClassImp(name)
Definition: Rtypes.h:364
TGeoRCExtension
Reference counted extension which has a pointer to and owns a user defined TObject.
Definition: TGeoExtension.h:37
TGeoExtension.h
TGeoExtension
ABC for user objects attached to TGeoVolume or TGeoNode.
Definition: TGeoExtension.h:20
Rtypes.h