Re: 4 beginner's questions on the PL Ada

[Mike H <postmaster@ada-augusta.demon.co.uk>]

Once again a thread in this news group shows a polarisation of mind sets 
concerning right and wrong approaches to writing a program. I am 
reminded of my teaching days when, even before writing a single piece of 
Ada code on the white board, I would initiate some class discussion on 
the question of whether time and duration are same and, if they are not 
the same, does it matter. I knew I could expect general agreement that 
the result of adding a pair of time variables was meaningless whereas 
subtracting such pair of times could be valid, but only if one was aware 
that the result was not a time. The fun would start when the discussion 
moved on to questions of how one might detect or, better still prevent, 
a time/duration program error. If I was lucky, opinions would become 
quite heated concerning personal responsibility and managerial 
responsibility should such an error reach a production version of a 
product.

When the dust began to settle I would ask whether it might no be useful 
if such an error could be detected at compilation time. Sometimes there 
would be a small minority who would greet that question with 
incredulity. More interesting to me was identifying those who showed an 
interest in how this might be achieved in well written Ada and, in 
comparison, those who were sufficiently sure of their own capabilities 
that they could regard any additional lines of defensive coding in any 
language as an unnecessary irrelevance. Worse still were those who would 
be deaf to the idea that although additional lines of declaration source 
code can be expected to change the resulting executable code that does 
not necessarily mean a change of the amount of generated execution code 
nor necessarily a change of execution times.

-- 
Knowledge is knowing a tomato is a fruit
Wisdom in knowing not to put it in the fruit salad.
Mike