Re: APQ

[Brian May <bam@snoopy.apana.org.au>]

>>>>> "Dmitry" == Dmitry A Kazakov <mailbox@dmitry-kazakov.de> writes:

    >> procedure Connect(C : in out Root_Connection_Type; Same_As :
    >> Root_Connection_Type'Class) is abstract;

    Dmitry> Are you going to clone connections between different DBs?
    Dmitry> The above looks like an attempt to emulate multiple
    Dmitry> dispatch.!

I read a documentation somewhere that said the code below is not
legal, and the above had to be used instead... The documentation said
the code body could check the types were correct. However, on advice
from Dmitry, I tried a test case with the code below, and it seems to
work fine. Need to keep my eyes open for that reference. Wonder if it
was that dodgy guide on the web about Ada for C++ programmers...

    Dmitry> It should be:

    Dmitry> procedure Connect
    Dmitry> (  C : in out Root_Connection_Type;
    Dmitry> Same_As : Root_Connection_Type   -- Same types required!
    Dmitry> )  is abstract;

    Dmitry> However would be is pretty useless, when you have a
    Dmitry> class-wide object at hand.

    Dmitry> I suppose that the idea was to make a copy of a limited
    Dmitry> object. Then it should better be:

    Dmitry> function Copy (C : Root_Connection_Type)
    Dmitry> return Root_Connection_Ptr is abstract;

    Dmitry> This would allocate a copy and connect it to the same
    Dmitry> DB. Because reference counting is intended you will need
    Dmitry> dynamic allocation anyway. The user will of course do it
    Dmitry> all with handles:

I have a suspicion this would not work as Root_Connection_Type is a
limited type. Or am I yet again mistaken?

Can somebody please let me know what applications a cloning function
has? I frequently hear of such functions, but rarely (if ever) needed
to use one.
-- 
Brian May <bam@snoopy.apana.org.au>