-- I appreciate all of the extra Ada capabilities that you have learned.
-- It is all good stuff.

-- Still, you have not incorporated many of the features for reusability that 
-- I requested, chiefly the use of a generic function for inputting the
-- number (look at my comments for the first version).
-- Also please change the name from DIGIT to something indicating a
-- number between -32768 and 32767, as you define it.
-- Please change the parameter string to include the entire output
-- string to generalize the procedure somewhat. 

-- G. Levine

From:	Eugene Giuliano

To:	Dr Levine
	levine@alpha.fdu.edu

Dr Levine,

Mailed under separate heading, is the second implementation of my
CALCULATOR program in Ada. I have implemented as many of your
suggestions as my Ada abilities permit. Below are some comments.

GENERAL COMMENTS:
  PLATFORM: Develpment was done using VAX/VMS Ada. The file naming
  convention observed for a SPEC was to use an "_" instead of a .abs
  extention, as per GEC's internal convention. 

  STYLE: I have formatted the code to be consistant (I think) with the
  style guide. This was accomplished with the aid of an automated 
  formatter - a.pr. The utility is part of the VADS Ada development 
  package and is hosted on a MIPS Unix platform. I will discuss this it 
  real-time with you. A handy utility like this would be quite useful 
  for our purposes. Perhaps one is available in the public domain.

  EXTERNAL MODULES: I have maintained the one module per file 
  implementation for now. Your comments about internalizing non-reusable 
  modules are most appropiate and are understood and accepted. My 
  original approach is based on a Fortran mindset. Clearly, proper Ada 
  development requires a more modern approach that I must adopt.
  My approach actually complicated the development since the order of 
  compilation became critical. This was an interesting learning 
  experience with the DEC Ada toolset.

SPECIFIC COMMENTS

  GET_FIRST_DIGIT was "generalized" (modified) to accept a string 
  parameter for the prompt and GET_SECOND_DIGIT was eliminated.

  PERFORM_OPERATION was fixed to use Exceptions and CHECK_DIVISOR was 
  eliminated. I am hesitating to make this a function since the caller 
  should NOT print a result if there is an error.

  PACKAGE CAL_FUNCTION and the related spec were implemented to give me 
  some experience with this feature of the language.

  GENERIC implementation is there in a half-baked way. At first I tried
  to develop CALCULATOR to handle any number type e.g. floating,
  integer, subtype. This lead to all kinds of problems and a lot of
  trouble.

-- Look at my code in the previous example, and send me your
-- work, even if it is half baked.  That is the only way to learn.
  
 I enlisted an Ada guru at one point to assist me. Eventually
  I (we) abandoned the approach since it was impossible to instantionate
  TEXT_IO.INTEGER with a private type.
-- You do not use a private type; you use a numeric type.
-- generic
--     type NUMBER is range <>;
-- Check my code. 
 I also experienced problems with
  the relational (/=) and mathimatical operators (+,/,*,-). Frustrating
  and very time consuming. A re-match is scheduled for the next
  incarnation of CALCULATOR.

  SIMPLE HEADERS were placed in all the files.