Re: Ada Annoyances

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 26/06/2017 23:40, Randy Brukardt wrote:
> "Maciej Sobczak" <see.my.homepage@gmail.com> wrote in message
> news:71c4fdcd-4213-4b84-b852-c8674cfaf717@googlegroups.com...
> ...
>>> In Ada, where redispatching requires explicit work, the vast
>>> majority of constructors will never make a dispatching call so there is
>>> very little risk.
> 
>> The vast majority? Where does this statistics come from?
> 
> Common sense. Constructors shouldn't be doing anything complicated in the
> first place, so there's not much reason for delegation.

This is an argument for type-specific constructors actually. You cannot 
have it both ways.

And constructor could be quite complicated if you don't want to push 
initialization to the type's end user. In essence making an object fully 
functional is either a complication for the original designer of the 
type  once declared or a complication for a user unfamiliar with the 
implementation details asked to bring half-baked object in order. I 
really hate APIs that require a dozen of calls to make plus some On_Init 
callbacks to handle before I could do anything with an object.

[...]

> As I tried to say yesterday, Ada does have a flaw in that allows dispatching
> calls within contructors (and more generally, inside of any primitive
> operations). That requires work of some sort, but it is possible, and it
> shouldn't be.

Hmm, but what are you going to do about Rosen's trick? All use-cases 
where it is used (to work around language problems, constructors 
included) must be eliminated first. Only then re-dispatch could (and 
must) be outlawed.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de