Re: on OO differnces between Ada95 and C++

[nabbasi@qualcomm.com (Nasser Abbasi)]

In article <Dn4J2F.uI@bton.ac.uk>, je@bton.ac.uk (John English) says:
>
>Nasser Abbasi (nabbasi@qualcomm.com) wrote:
>: Lets also assume that we need to define a Money Type, defined in
>: the base class Account.     
>
>: In Ada95 this type is defined in the package Account.ads that also
>: includes the definition of the tagged record type Account (along with
>: operations that act on Account type).
>
>: Now, In Ada95, a client that wishes to use Saving_Account type (and
>: any operations on it) will "with" the Saving_Account Package.


>
>If the spec of Saving_Account has "with Account" at the beginning,
>"with Saving_Account" will imply "with Account". 

I do not think this is true. That is the main reason I asked the 
question in the first place. (I did not like having to "with" 
a package that was allready with'ed by a package I am "withing" ).

If what you say was the case, then types defined in package "A"
will be seen by clients to a package "B" where "B" has with'ed A. But
it is not so. Clients of "B" must also 'with' "A" to see types defined
in "A" even though "B: has allready  with'ed "A".

Thanks all for your inputs, I see 2 solutions now to this. I like the
child package solution mentioned by a number of people (including
John English).

I also like the fact that withing Ada packages is not transitive. when
I "with" Package A, only what is in A is visible, and not every thing
that in the chain of packages that A might have "withed" (unless 
offcourse tagged types are involved). This way seems to give better 
control of things. In C/C++ including files A.h, will also "pull" in
everthing that is included by A.h to the client level and make
these things visible at the client level.. 

Nasser