Re: Constructor in ADA9X

[eachus@spectre.mitre.org (Robert I. Eachus)]

In article <D3orIs.62t@inmet.camb.inmet.com> stt@henning.camb.inmet.com (Tucker Taft) writes:

  > One last point -- sometimes you don't want a constructor
  > to be inherited, because the set of parameters it takes
  > is dependent on the specific type for which it was designed.
  > If you declare the constructor in the same package as the
  > associate type T, and it returns the type T, then it *will*
  > be inherited.  One nice way to avoid undesired inheritance for
  > certain constructors is to put all such constructors in 
  > a "child" package of the package where the original type
  > is defined.  

   What Tucker said is perfectly correct, but may be misleading to
novices.  If a function has a controlling result (of a tagged type),
then it must be overridden when inherited by a non-abstract type.

   (Hmmm...  That is also pretty confusing.  What Tucker is really
saying is that in general in Ada 9X, you usually don't want to declare
constructors where they will be inherited, because the person who
declares a type derived from it may be forced to define a useless or
"junk" constructor.  You can have inherited constructors if you want,
but usually you don't want.)

   
--

					Robert I. Eachus

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