[Insight-users] Why is itkDataObject::m_Source a WeakPointer?

[Miller, James V (Research)]

The source is a WeakPointer because the Source points to the DataObject and 
the DataObject points to the Source.  If they both held SmartPointers to each
other, then we would have a cyclic reference loop and neither the Source or the 
DataObject could ever be deleted.



> -----Original Message-----
> From: Th. Boettger [mailto:t.boettger@dkfz-heidelberg.de]
> Sent: Friday, October 11, 2002 12:25 PM
> To: ITK Mailing List
> Subject: [Insight-users] Why is itkDataObject::m_Source a WeakPointer?
> 
> 
> Hi all,
> 
> I am trying to construct a filter pipeline in a member function and to
> return the resulting data object *without* calling Update() 
> in this method.
> When trying to update the returned data object outside, the 
> source is set to
> NULL. The reason is that m_Source member is defined as a weak 
> pointer, thus
> the reference count of the process objects (the source) is 
> not incremented.
> 
> Why is it a WeakPointer? How can I avoid this problem?
> 
> class itkDataObject
> {
> ...
> mutable WeakPointer<ProcessObject> m_Source;
> ...
> }
> 
> Thanks in advance!
> 
> 
> 
> ---
> Dipl.-Inform. Thomas Boettger
> Deutsches Krebsforschungszentrum         (German Cancer 
> Research Center)
> Div. Medical and Biological Informatics H0100    Tel: (+49) 
> 6221-42 2328
> Im Neuenheimer Feld 280                          Fax: (+49) 
> 6221-42 2345
> D-69120 Heidelberg                            e-mail: 
> t.boettger@dkfz.de
> Germany                      
http://www.dkfz.de/mbi/people/thomasb.shtml


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