Re: Ada Singleton Pattern

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

On Tue, 14 Sep 2004 17:04:17 +0200, Florian Weimer wrote:

> * Dmitry A. Kazakov:
> 
>> Only if the scope of the singleton is unknown, and so need to be dynamic.
>> But it is not the case for the example given. The scope of the singleton is
>> one of the package. The package itself can be nested (not to be at the
>> library level). So clients are prevented from accessing it after its
>> finalization by the compiler.
> 
> Oh, come on, you should be able to abstract a bit from the concrete
> code you gave. 8-) Often, singletons are used to manage external
> resources, and some cleanup operation is required.

But that is unrelated to the issue of whether the scope is known. If the
scope is known, then it is quite easy to ensure that there will be no
dangling references to the object. Ada visibility rules ensure that. If it
is unknown, then that is not just the singleton issue. It is rather about
pointers, smart pointers, handles, garbage collection etc. From the
original post it is unclear what is actually needed. So I'd stick to my
trivial case for a while. (:-))

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