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From: Stephen Leake <stephen_leake@stephe-leake.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada and "early return" - opinion/practice question
Date: Mon, 15 Mar 2021 10:31:27 -0700
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John McCabe <john@mccabe.org.uk> writes:

> I hope this isn't a FAQ (it's hard to find relevant articles) but can
> someone guide me on the 'normal' treatment in Ada style of what
> appears to be referred to (by C/C++ programmers) as early-return.
>
> For example, you have a C++ function (pseudo code sort of thing):
>
> <sometype> fn(<some parameters>)
> {
>     if (<some undesirable condition 1>)
>     {
>         return <something bad happened 1>;
>     }
>
>     if (<some undesirable condition 2>)
>     {
>         return <something bad 2>;
>     }
>
>     if (<some undesirable condition 3>)
>     {
>         return <something bad 3>;
>     }
>
>     // Only get here if everything's good...
>     <do some real stuff>
>     return <something good>;
> }
>
> I've probably mentioned this before, but it's a long time since I used
> Ada in anger and I don't remember seeing stuff like that when I did
> use Ada a lot; does anyone write stuff like that in Ada?

Sometimes I write code that way, sometimes I have a Result variable that
gets set along the way. The latter mostly when Result is a container of
some sort, and parts of it get set at different points.

I would tend to use an exception for "something bad", but that depends
on the overall design.

There are various maintenance issues on both sides; the summary is
"editing existing code is a pain" :(.

> Hope this is ok to ask!

Sure; there are times when one style is overwhelmingly better (ie
requiring matching end names); this just isn't one of them.

-- 
-- Stephe