Re: Why constructing functions is a mess [was Language lawyer question: task activation

[Georg Bauhaus <rm.tsoh.plus-bug.bauhaus@maps.futureapps.de>]

Dmitry A. Kazakov wrote:

> Topic: large system design, information hiding:
> 
>       type T (<>) is abstract tagged limited private;
>    private
>       type T (...constraints...) is abstract tagged limited record
>          ...
>       end record;
> 
> In order to be used in
> 
>    type S is new T with ...;
>    function Create (....) return S;

How/Why should this derivation be possible? (Deriving publicly
from an abstract limited type with unknown discriminants--to me,
the <> signals the intent of the author of T, namely that T
should be considered none of our business?)


> Remember? Constructor is not function. It never will. See the problem?

Assuming C++ has constructors, will your arguments apply
in the following examples (just trying to understand):

class T
{
public:
  virtual void op() = 0;
private:
  T(char constraint) : c(constraint) {}
  char c;
};

class S : public T
{
public:
  S() {}
};

(Note: no suitable default constructor in T)