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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: In-Out Parameters for functions
Date: Fri, 27 Feb 2004 17:37:42 -0600
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Date: 2004-02-27T17:37:42-06:00
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"Vinzent 'Gadget' Hoefler" <nntp-2004-02@t-domaingrabbing.de> wrote in
message news:t9fr30tnl8rh0ain01qeqq17ottovqdso3@jellix.jlfencey.com...
...
> So it might be possible that in the parsing/compiling process the
> order specified in the named notation simply gets reordered to the
> order of how the parameters are declared.

Right. That's exactly what Janus/Ada does internally for named notation, and
the arguments are evaluated in the order that they get passed; no matter
what order they were passed in.

> IMO, it is easier to just not rely on side-effects. No side-effects, no
problems.

Which was the basic idea behind Pure - a way to declare that functions have
no meaningful side effects. (Caching values and records calls in a
scratchpad aren't meaningful). It's unfortunate that applying the "Pure"
categorization is so difficult. GNAT provides a solution here - pragma
Pure_Function - which essentially declares to the compiler that the function
has no meaningful side effects without any checks. (This pragma is being
considered for Ada 200Y.) One could imagine a coding standard which required
all functions used in non-trivial expressions (that is, not used alone) to
be marked either Pure or Pure_Function.

                    Randy.