Re: Ada and "early return" - opinion/practice question

[John McCabe <john@mccabe.org.uk>]

On Monday, 15 March 2021 at 17:02:09 UTC, Dmitry A. Kazakov wrote:
> On 2021-03-15 17:46, John McCabe wrote: 
> > 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): 
<..snip..>

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

Thanks for that Dmitry; the subtlety here is the use of elsif thoughout though, which tends to be skipped in C++ sources. Put that way, what I originally 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 conditions have been satisfied, and you're less likely to get some random behaviour because of a missing return in the bunch of earlier tests.