Re: DogCows or Polymorphism in the Hurd

[Jonathan S. Shapiro]

On Thu, 2006-02-09 at 03:54 +0100, Marcus Brinkmann wrote:

> As you said yourself, less and KDE/Gnome applications are aware of the
> hybrid types, so they know how to handle them.

No. less and KDE/Gnome applications are *simulating* hybrid types. This
is quite different from DogCow types, because the application is
defining the semantics of the simulation.

> In both cases, no ambiguities arise.  The problematic case is legacy
> applications that can work on Files _and_ can work on Directories, and
> get confused if something is a FileDirectory (DogCow)....  This is the
> fundamental problem you have to solve if you want to combine both
> interfaces into one.

We have established that this does NOT capture the fundamental problem.
All of the cases you identify are real cases, but this example is a
narrow sub-case of a much bigger problem. The larger problem is revealed
when you ask

  "I have a file in one format. What does the DogCow interface
   look like when a translator wishes to present a second view
   that interacts **as a file** of some other format."



shap