Re: Ada 2012: In-out parameters for functions

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

Le Wed, 01 May 2013 21:37:43 +0200, Dmitry A. Kazakov  
<mailbox@dmitry-kazakov.de> a écrit:

> On Wed, 01 May 2013 21:04:03 +0200, Yannick Duchêne (Hibou57) wrote:
>
>> In/out (both way) parameters may be another story, and may more suggest
>> this is a procedure and not a function,
>
> function Read (Stream : in out Root_Stream_Type) return String;
>

:D

This is more a procedure than a function (it either won't return the same  
the next time invoked with the same argument or either the argument can  
never be considered to be the same as it use to be any‑more), and a  
function construct is used only because it is preferable to return an  
unconstrained type (as Shark8 mentionned) than an access to the same  
object allocated on the heap and returned via an out mode access type  
parameter of a procedure.

That's a good example of how a construct may not always match the intended  
semantic; it may happens one use a function to implement a procedure, or a  
procedure to implement a function.

I feel `function` and `procedure` in Ada means something at the  
implementation level more than at the intention level, even if many times  
both matches as gloves and hands.

-- 
“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