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From: stt@inmet.inmet.com
Newsgroups: comp.lang.ada
Subject: Re: Updating IN OUT's after exceptions
Message-ID: <20600103@inmet>
Date: 1 May 91 22:56:00 GMT
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Nf-From: inmet.inmet.com!stt    May  1 18:56:00 1991
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Re:  Updating IN OUT's after exceptions 
         Query on  5:18 am  Apr 30, 1991 by stuartw@tove.cs.umd.edu

> In the enclosed program, I raise an exception inside a subroutine after
> making an assignment to an IN OUT parameter.  In the first case, the
> parameter is a scalar, in the second it is not.  Everything else is the
> same, except the resulting behavior.  Is this permitted by the LRM?
> I know that compilers can pass non-scalar parameters by copy-in/copy-out
> or reference, but should that effect exception handling?  Is Ada/9x
> addressing this?
> 
> Thanks.
> 
> Stuart.  (weinstei@kong.gsfc.nasa.gov)

The Good Old Reference Manual, section 6.2:12 says the following:
  If the execution of a subprogram is abandoned as a result of an exception,
  the final value of an actual parameter [...] can be either its
  value before the call [if passed by copy] or a value assigned
  to the formal parameter during the execution of the subprogram
  [if passed by reference].

In other words, the compiler "does the right thing."

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