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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: 'size attribute inheritance
Date: 1997/08/17
Message-ID: <dewar.871839941@merv>#1/1
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Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-08-17T00:00:00+00:00
List-Id: <comp.lang.ada>


Ken said

<<I suppose this is technically true, but couldn't the effect of
pragam Normalize_Scalars, when combined with 'Valid and/or range
checking, be informally described as checking for uninitialized
variables?>>

Be careful! First, Normalize_Scalars does not guarantee that the variable
will be initialized with an out of range value (and indeed for a type
like Integer, it is almost certain that there is no such thing as an 
out of range value).

Second, the compiler is in many cases allowed to assume that a variable
is in range, so it may not always do a check where you expect it. In
particular, for a simple assignment, where the subtype is the same on
both sides, there is no requirement to perform a check, since assigning
the out of range value is an acceptable behavior for the error of
referencing an uninitialized variable.

Still, you are generally right, NS will approximate a check for 
uninitialized variables in practice.