Re: Private extension of a synchronized interface

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

On 2019-02-16 01:52, Jere wrote:
> I'll get to my ultimate goal later, but while following various
> rabbit trails, I came across a situation I couldn't solve.  GNAT
> allows you to make private extensions to synchronized interfaces
> and it allows you to complete those private extensions with
> protected types.  I can't, however, figure out how it overrides
> the abstract procedures and functions of the synchronized interface.
> 
> If I don't specify an override and try to call the procedure, it complains
> that the procedure is abstract.  If I try to override the abstract
> function, it complains that the signature doesn't match the one in
> the protected body.  I don't know if this is a GNAT issue or
> something that Ada doesn't allow.  Here is some test code.  It
> compiles as is, but there are two parts that if you uncomment
> either one of those it fails to compile.

Reading RM 9.5.2 (13.2/2) does not really help:

"if the overriding_indicator is overriding, then the entry shall 
implement an inherited subprogram;"

An inherited subprogram is already implemented per, well, inheritance. 
May be it means:

1. shall implement a primitive operation (it overrides here);

2. shall implement an overridden primitive operation (it implements 
overriding declared earlier).

Neither #1 nor #2 work.

But synchronized interfaces are totally bogus from the software design 
POV. It is a pure implementation aspect exposed. Why do you care? 
Aggregate a protected object and delegate primitive operations to it.

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