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obj.copyobject [2010/06/12 04:37] (current)
jochen created
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 +====== obj.CopyObject ======
  
 +===== Motivation =====
 +While the object-oriented interface and calling convention for xff objects is suitable in most situations (e.g. a method that alters an object by, for instance, adding a volume-of-interest to a VOI file), there is the occasional need to create a temporary working copy of an object which, once the task is completed, can be discarded. Alternatively,​ it might be desired to create a derivate object (e.g. a VMR with a spatial filter applied) without changing the source object.
 +
 +In both these situations, the ''​obj.CopyObject''​ call brings the desired solution.
 +
 +===== Reference ('​obj.Help('​CopyObject'​)'​) =====
 +<​file>​ AFT::​CopyObject ​ - copy object to new
 + 
 + ​FORMAT: ​      ​copied = obj.CopyObject;​
 + 
 + No input fields
 + 
 + ​Output fields:
 + 
 +       ​copied ​     xff object with own storage in global xffcont
 + 
 + ​TYPES:​ ALL</​file>​
 +
 +===== Usage example =====
 +<code matlab obj_copyobject_example.m>​% load a VMR
 +vmr = xff('​new:​vmr'​);​
 +
 +% create a copy (does NOT YET double the allocated memory!)
 +smoothed = vmr.CopyObject;​
 +
 +% smooth VMRData
 +smoothed.VMRData = uint8(floor(smoothdata3(double(vmr.VMRData),​ [2, 2, 2])));
 +
 +% histogram of differences
 +hist(vmr.VMRData(vmr.VMRData ~= 0) - smoothed(vmr.VMRData ~= 0), 100);</​code>​
 +
 +===== Notes =====
 +Just as mentioned in the example above, due to Matlab'​s internal (and genially coded) logic, the memory requirements of a copy object are almost 0 (only the pointers in the global struct need a new copy). Only when a member in the copied object (in this case the VMRData field) is altered, will the memory manager of Matlab allocate a new chunk of memory. This is particularly useful if the copied object is only created because some text or other minor alteration is made for compatibility reasons for internal processing!
obj.copyobject.txt ยท Last modified: 2010/06/12 04:37 by jochen