Re: Classes vs Tagged Types - Terminology

[asuvax!ennews!enuxhb.eas.asu.edu!koehnema@gatech.edu (Harry Koehnemann)]

In article <1993Apr5.155419.8598@evb.com> jgg@evb.com (John Goodsen) writes:
>In <1993Mar25.155650.16244@inmet.camb.inmet.com> 
>stt@spock.camb.inmet.com (Tucker Taft) writes:
>
>>In Ada 9X, it is only class-wide types (named "T'Class") that provide
>>subclass matching.
>>                      ^^^^^^^^^^^^^^^^^
>                       Didn't you mean "tagged types" :-)
>
>Can we take this as an indicator that you are about ready to
>abondon the "tagged type" terminology and adopt the more
>appropriate "class type" terminology?  It seems that even
>members of the 9X project are shying away from using "tagged
>type" these days, so why don't just finish the scenario and
>adopt the "class type" syntax and terminology ...

The term "class-wide" appears to apply to the usage of a type
classification (when declaring a parameter type for a subprogram
specification), while your favorite term "tagged type" is used
during the definition of the classification . i.e. "tagged" isn't
going away.

IMO, it would be a large mistake to refer to Ada's tagged types
as classes.  I understand your desire to use terms common in the
OO world, but great confusion lies ahead for those OO people that
have programmed using a class construct.  Classes and type extensions
are by no means the same construct and it is appropriate to make
their names distinct - "tagged"/"extended"/???, but not "class".
--
Harry Koehnemann			Arizona State University
koehnema@enuxha.eas.asu.edu		Computer Science Department