Re: good software engineering (was: mixing integer and logical ops)

[eachus@mitre-bedford.arpa (Robert I. Eachus)]

In article <C7nJIx.3n7@crdnns.crd.ge.com> groleau@e7sa.crd.ge.com (Wes Groleau 
X7574) writes:

  > I think the reason is not that Ada makes it easier to spot "bad code"
  > Rather, IMHO, it's that the "Ada community" has from the beginning
  > had an attitude in favor of "pretty" and readable source code.  The
  > C community on the other hand is unsuccessfully trying to change a
  > culture that EXPECTS code to be unreadable.

    I think it is a little more complex than that.  Why did the
culture evolve that way, and why does it evolve similarly when new
communities adopt Ada?

    First of all, declarations in Ada come first, and it is hard to
write unreadable declarations.  So if the private part or the sequence
of statements is obtuse, the reader--even if he or she is also the
author--notices the increase in the fog level.  (Yes, an expert can
write a declarative part with a high fog index.  But by the time he
has that capability, he has also been conditioned not to.)

     Second, Ada tends to magnify little flaws out of proportion.
When you write Int(Integer(Int'First) + N - 1) the need to rethink the
type of N is immediately apparent.  In this case, which happened to me
earlier this week, the reason for the expression was that N could be
out of range of the generic formal type Int.  Replacing the variable N
by a new variable, linearly related to N, but always in range, got rid
of the need to use Integer for anything.

     So Ada code is held to a high standard of beauty not only because
elegence in Ada is usually easy, but also because the occaisional wart
is so ugly that anyone with the least bit of pride will try to clean
it up.

     Yes the culture is important, but the language keeps the culture
the way it is.  A similar case is short variable names in C or APL.
This not "just" a cultural thing, those languages tend to make long
names look silly.  (C also had an early restriction on the number of
significant characters (8) and on external names--but that was an
implementation restriction.  C has always allowed arbitrarily long
identifiers.)


--

					Robert I. Eachus

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