Create the native int8 from the contents of the specified DOFValue. 
- Parameters
 - 
  
    | self | The DOFValue to be extracted. This must represent a single value of type int8, and must not be NULL. | 
  
   
- Returns
 - The new int8 from the contents of self.
 
- Exceptions
 - 
  
    | 0 | is returned if an invalid parameter was detected.  |