Re: Ada and Automotive Industry

[dewar@merv.cs.nyu.edu (Robert Dewar)]

Adam says about my array declaration (1 .. 10) of ...

"I think the idea of always specifying Integer explicitly is valuable,
but the example chosen is unfortunate.  In the above case, the
explicit use of Integer "draws attention" to something that is in this
case irrelevant.  Of course, if you're specifying integer types for
all your array bounds, you should do it here too for consistency.  But
I hope that if I code the above statement, no one reading the code is
going to pay much attention to the fact that I'm using an
implementation-dependent integer type."


And what a NICE example this is of why exactly this is insidious. Adam
just assumes that because the bounds are 1..10 all is OK, but the trouble
is that once you have this delaration then type integer has crept in
silently. Consider:

     for x in arr'Range loop
        if Is_Prime (2 ** X - 1) then ....

and suddenly we have a *real* dependence on type integer that is very
hidden from view. I stick by my original point, and I do not apologize
for the example, it was intentional!