Re: Ada2012 : Expression functions and extended return statements

["Yannick Duchêne (Hibou57)" <yannick_duchene@yahoo.fr>]

Le Fri, 06 Jan 2012 09:45:26 +0100, Martin <martin@thedowies.com> a écrit:

> Am I correct in thinking these 2 parts of the language can't be
> 'mixed'?...
>
> There doesn't seem to be anything that allows anything like, e.g.
>
> package Foo is
>    type T (<>) is tagged private;
>    function Create return T is
>       (Result : T do Result.I := 1);
> private
>    type T is tagged record
>       I : Integer;
>    end record;
> end Foo;

Private stuff in the public part is funny, don't you think ?

> Also, on the topic of extended return statements...
>
> What's the rational for having to explicitly repeat the return type?
> Seems rather redundant to my eyes. I wouldn't have minded:

At least because Ada does not have Type Inference. You have to declare the  
returned entity, just like you would do with a classic return‑by‑copy (*).  
You have to build something in‑place, so have to declare what you build,  
even if it's not tagged and class‑wide.

Sorry, can't see better words to explain.

(*) Example:

    function F return String
    is
       Result : String;
    begin
       Result := "....";
       P (Result); -- in/out Result
       -- Etc.
       return Result;
    end F;


-- 
“Syntactic sugar causes cancer of the semi-colons.” [1]
“Structured Programming supports the law of the excluded muddle.” [1]
[1]: Epigrams on Programming — Alan J. — P. Yale University