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From: dewar@cs.nyu.edu (Robert Dewar)
Subject: Re: some questions re. Ada/GNAT from a C++/GCC user
Date: 1996/04/02
Message-ID: <dewar.828448332@schonberg>#1/1
X-Deja-AN: 145422360
references: <wnewmanDoxrCp.DKv@netcom.com>
 <4je9ju$174r@watnews1.watson.ibm.com>
 <ROGOFF.96Mar28134118@sccm.Stanford.EDU> <4jhe1v$m0g@dayuc.dayton.saic.com>
 <4jp17p$17vn@watnews1.watson.ibm.com> <3160B03B.5230@mcs.com>
organization: Courant Institute of Mathematical Sciences
newsgroups: comp.lang.ada
Date: 1996-04-02T00:00:00+00:00
List-Id: <comp.lang.ada>

Mike said

"I'm confused. I thought I read an explicit rule (in Barne's book) that
no order of evaluation was specified for declarations."

You are *indeed* seriously confused. Declarations in Ada are elaborated
strictly in order, and John Barnes certainly did not say anything that
corresponds to your memory.

In fact the serial elaboration of declarations (conciously copied by the
way from Algol-68) is one of the key design points in Ada.

Note of course that whenever we say something is done strictly in order,
we are talking about the formal semantic description, excluding RM 11.6.
There are two respects in which this description may not correspond to
the generated code.

1. THe compiiler is always allowed to shuffle things around if no Ada
	program can see any effect (using the formally defned meaning
	of external effect) of the change.

2. 11.6 allows certain chnges in the semantics of raising of
	predefined exceptions. of course this is relevant only if
	a declaration raises an exception.