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From: Jacob Sparre Andersen <sparre@nbi.dk>
Newsgroups: comp.lang.ada
Subject: Re: Why is the destructor called multiple times after I declare an
 object?
Date: Wed, 13 Jan 2016 21:18:44 +0100
Organization: JSA Research & Innovation
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Date: 2016-01-13T21:18:44+01:00
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Bob Duff <bobduff@theworld.com> writes:
> Brian Drummond <brian@shapes.demon.co.uk> writes:

> For nonlimited types, the compiler is free to use build-in-place if it
> can prove that it's equivalent to return-by-copy.  It's often not
> equivalent.  For example:
>
>     X := Init;
>
> What if Init raises an exception after partly modifying the result?
> In that case X should not be modified, so the result object of Init
> and X had better not be at the same address.

But if:

a) There is no exception handler between the assignment and leaving the
   scope of X, build-in-place is okay (but impractical)?

b) The compiler can prove that no exceptions can occur after the first
   modification of the result inside Init, build-in-place is okay?

Greetings,

Jacob
-- 
"The butcher backed into the meat grinder and got a little behind
 in his work."