[vtkusers] General file reader

[Sunrise]

I would like to read different file formats as input to my class.
Previously, I wrote a custom reader that used different readers inside
it, based on parsing user input and extracting the file extension, then
switching to appropriate reader. For example vtkUnstructuredgridReader
for *.vtk input and vtkXMLUnstructuredGridReader for *.vtu input.

I would like to ask, is there any method that I can leverage reading
almost all supported formats (specifically for unstructured grid data,
such as vtk, vtu, ex2, ...) without parsing user input?

Thanks