function ds = setinterpreter(ds,funchandle)
   %SETINTERPRETER changes the associated interpreter function
   % datasource = setinterpreter(datasource,function_handle)
   
   if ~isa(funchandle,'function_handle')
      error('Trying to set a function handle to a %s',class(funchandle));
   end
   ds.interpreter = funchandle;
   % ds = datasource(funchandle,ds.file_string,ds.file_args{:});
end