Chapter 14 - Successive Refinement

• Argument parser
  • Args class constructed with format string describing arguments and list of arguments
  • Methods to get arguments as type, if type is wrong get an exception
• Initial design before refactor
  • Hash map for arg name -> value for every argument type
  • Adding a new type requires updating multiple parts of Args
    • Hash map
    • Parsing the schema definition
    • Parsing the command line based on schema definition
    • Getting the value
  • Was built incrementally, first version only accepted bools
    • Logic for bool values was duplicated for other types
• ArgumentMarshaller class
  • Want to move type switches out of Args
  • Easier to add a new type by defining a new class with all the logic in one place and dispatching using inheritance
  • Refactoring behaviour into ArgumentMarshaller class, which will later be pushed into derivatives - incrementally with tests rather than all at once
  • Initially kept separate maps but wrapped the value with the marshaller to handle parsing, getting
  • Then refactored again into one map with dispatching
    • Also done one type at a time
  • Setting was done after
• Setting values
  • Bool arguments are just set to true
  • Setting Integer and string arguments need the next value in the array to set their value
  • Currently using the index and array
  • Use an Iterator instead so the marshaller set only needs one argument instead of two
• Exceptions
  • Another responsibility for the Args class
  • Move into an argsException class
  • Also throwing ParseException from Integer.parseInt, which doesn't belong to us