Re: "Must instantiate controlled types at library level." Why?

[Martin Krischik <krischik@users.sourceforge.net>]

Peter C. Chapin wrote:

> Martin Krischik <krischik@users.sourceforge.net> wrote in
> news:13392802.3gDeTK7ybb@linux1.krischik.com:

> Actually I tried this modification. In fact, the three C++ compilers I
> used *do* produce a compile time error on this code. In particular the use
> of an auto variable in the member function of a local class is
> specifically illegal. The relevant language from the C++ standard is in
> section section 9.8, paragraph 1: "Declarations in a local class can use
> only type names, static variables, extern variables and functions, and
> enumerators from the enclosing scope." The standard then goes on to give
> an example showing that the use of an auto variable is illegal.

Well, here you have a good example of the difference of Ada and C++. Ada has
a complete ban on the construct while C++ goes out and about to ban only
the tricky part.

Off course the C++ ISO standart is 200 pages longer the Ada Standart. And
that's without tasking, without protected types, without indefinite types
and with a need for clone() functions. Just in case you did not know:

P is tagged ....
P_Class is access P;
C is new P ....

A_C : C := ...
A_P : P'Class := P'Class (A_C); 
A_P_Ptr : P_CLass := new P'CLass'(A_C);

A_P and A_P_Ptr will contain a copy of C.

With Regards

Martin

PS: I hope you don't mind my other post to much. You do dig deeper and you
do know the ISO standart so my rant about the average C++ programmer does
not apply to you.

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