Path: utzoo!attcan!uunet!ncrlnk!ncrcae!hubcap!gatech!bloom-beacon!apple!bbn!inmet!ishmael!inmet!ada-uts!stt
From: stt@ada-uts
Newsgroups: comp.lang.ada
Subject: Re: Implicit conversion?
Message-ID: <57900090@ada-uts>
Date: 9 Mar 89 15:40:00 GMT
References: <5678@sdcrdcf.sm.unisys.com>
Lines: 18
Nf-ID: #R:sdcrdcf.sm.unisys.com:-567800:ada-uts:57900090:000:694
Nf-From: ada-uts!stt    Mar  9 10:40:00 1989


W.r.t.: X := MAX_INT - MAX_INT;
You are correct that formally the conversion to
tiny integer takes place at the leaves of the expression,
however 4.5:7 in the LRM states:
  The predefined operations on integer types either yield the
  mathematically correct result or raise the exception NUMERIC_ERROR.

Hence it is perfectly legal to perform intermediate calculations
with predefined operators using more accuracy than the declared type.
I suspect that most Ada compilers will evaluate "static" expressions
(see 4.9 for definition) with infinite precision, since
they are required to evaluate all static *universal* expressions
exactly.

S. Tucker Taft
Intermetrics, Inc.
Cambridge, MA  02138