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From: "Jeffrey R. Carter" <spam.jrcarter.not@spam.not.acm.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada and "early return" - opinion/practice question
Date: Mon, 15 Mar 2021 19:37:02 +0100
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On 3/15/21 5:46 PM, 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):
> 
> <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?

Other than the use of exceptions rather than a return code, this is a standard 
idiom in Ada. It's much easier to read and understand than the Pascal approach, 
just as a "loop and a a half" is much clearer with an exit than the Pascal approach.

I seem to recall Robert Dewar arguing for this style on here many years ago.

-- 
Jeff Carter
"Choose a data representation that
makes the program simple."
Elements of Programming Style
188