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Newsgroups: comp.lang.ada
Date: Mon, 15 Mar 2021 10:29:12 -0700 (PDT)
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Subject: Re: Ada and "early return" - opinion/practice question
From: John McCabe <john@mccabe.org.uk>
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On Monday, 15 March 2021 at 17:02:09 UTC, Dmitry A. Kazakov wrote:
> On 2021-03-15 17:46, John McCabe wrote:=20
> > I hope this isn't a FAQ (it's hard to find relevant articles) but can s=
omeone guide me on the 'normal' treatment in Ada style of what appears to b=
e referred to (by C/C++ programmers) as early-return.=20
> >=20
> > For example, you have a C++ function (pseudo code sort of thing):=20
<..snip..>

> I see nothing wrong with it. In Ada:=20
>=20
> function fn (<some parameters>) return <sometype> is=20
> begin=20
> if <some undesirable condition 1> then
> return <something bad happened 1>;
> elsif <some undesirable condition 2> then=20
> return <something bad 2>;=20
> elsif <some undesirable condition 3> then=20
> return <something bad 3>;=20
> else --Only get here if everything's good...
> <do some real stuff>=20
> return <something good>;
> end fn;=20

Thanks for that Dmitry; the subtlety here is the use of elsif thoughout tho=
ugh, which tends to be skipped in C++ sources. Put that way, what I origina=
lly wrote would be:

<sometype> fn(<some parameters>)
{
    if (<some undesirable condition 1>)
    {
        return <something bad happened 1>;
    }
    else if (<some undesirable condition 2>)
    {
        return <something bad 2>;
    }
    else if (<some undesirable condition 3>)
    {
        return <something bad 3>;
    }
    else
    {
        // Only get here if everything's good...
        <do some real stuff>
        return <something good>;
    }
}

I probably wouldn't mind that layout so much, since it makes it clear that =
the code that's done at the bottom only happens when all the other conditio=
ns have been satisfied, and you're less likely to get some random behaviour=
 because of a missing return in the bunch of earlier tests.