[Insight-users] Smart pointers as function argument

[David Pastor]

Hi,

Actually I did something similar. I was trying this approach instead

int function(IType::Pointer in, IType::Pointer out){
//Filter setup here...

out=filter->GetOutput();

out->Update();

out->DisconnectPipeline();

WriterType::Pointer writer = WriterType::New();

writer->SetFileName("o.mhd" );

writer->SetInput(out);

writer->Update();

}

but this sort of pointer unification does not work. The writer inside of the 
function creates the correct image but using a writer over out when is back 
to the main does not produce the same image. Actually you get an empty 
image. I thought to handle the reference count of the pointers to fix this, 
but i'm not sure it will work. I'll try your fashion even though i prefer to 
have the return value for exit code purposes.

Thanks
David

> Hi,
>
> I find the same issue - the pipeline model just doesn't scale.
>
> You need the following code at the end of each function that returns
> an image pointer - see my readIm function below. The critical part is
> the Update() call followed by the DisconnectPipeline() call. You can
> ignore the exception handling for non io functions in most cases.
>
> typename TImage::Pointer readIm(std::string filename)
> {
>  typedef typename itk::ImageFileReader<TImage> ReaderType;
>  typename ReaderType::Pointer reader = ReaderType::New();
>  reader->SetFileName(filename.c_str());
>  typename TImage::Pointer result = reader->GetOutput();
>  try
>    {
>    result->Update();
>    }
>  catch(itk::ExceptionObject &ex)
>    {
>    std::cout << ex << std::endl;
>    std::cout << filename << std::endl;
>    return 0;
>    }
>    result->DisconnectPipeline();
>    return(result);
> }
>
>
> On Tue, Nov 17, 2009 at 4:12 AM, David Pastor <david.pastor at die.upm.es> 
> wrote:
>> HI,
>>
>> I'm trying to have a library with some functions I use to process Images
>> with ITK.
>>
>> What I do is:
>>
>> FilterApi f = new FilterApi();
>> InputType::Pointer filtered = InputType::New();
>> f->filtering(reader->getOutput(), filtered, arg1, arg2);
>>
>> inside of filtering I have some filter and filtered = 
>> filter->GetOutput();
>>
>> The function workst, and the filtered image is ok inside the function 
>> range.
>> But in my main framework, the filtered image is null. In other words, the
>> data is lost when you get out from the function and it is not persistent
>> even though i created the pointer in my main.
>>
>> I imagine this is something related to SmartPointers. Is there any way to 
>> do
>> this? it's a bit tiring to write the same blocks of code in each main.
>>
>> cheers
>> david
>>
>>
>>
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>