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From: Maciej Sobczak <see.my.homepage@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Limited_Controlled and out parameters
Date: Sat, 23 Jun 2012 05:02:09 -0700 (PDT)
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Date: 2012-06-23T05:02:09-07:00
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W dniu pi=C4=85tek, 22 czerwca 2012 22:22:57 UTC+2 u=C5=BCytkownik Randy Br=
ukardt napisa=C5=82:

[...]
> Since his example includes a component with an access type, it is always=
=20
> included in this bullet, so the behavior of the parameter is the same for=
=20
> "in out" and "out". And thus it is safe and reasonable to check if the=20
> object is already in use.

Thank you very much for a thorough explanation, this now makes sense.
Still, the solution does not feel very comfortable - the language seems to =
be somewhat spoiled by such nuances. Is it OK to read "out" parameters? Wel=
l, it depends on things that are defined far away from the place in questio=
n.

> (And I agree, don't make these things limited unless you really must not=
=20
> allow assignment. It's not that hard to write a proper Adjust routine for=
 a=20
> type like this one. "Limited poisoning" is a real problem in practice.)

I don't fully agree here - I would rather approach it the other way round: =
start from the most limited (pun intended) set of operations and add to the=
m only when necessary. Automatic call to Finalize is not necessarily what I=
 want to have in such places - the type in question might be much more comp=
lex than what I have presented and the problematic procedure need not rewri=
te the whole object. But then I would use "in out" mode to reflect the fact=
 that the post-call state depends on pre-call value.

--=20
Maciej Sobczak * http://www.msobczak.com * http://www.inspirel.com