On Mon, May 02, 2005 at 06:49:10PM +0200, Thomas Sandla▀ wrote:
> David Storrs wrote:
> >Let's move this away from simple types like Str and Int for a moment.
> 
> If you consider them simple...

When compared to

    "arbitrary-class-that-was-defined-by-
        arbitrary-programmer-of-
            arbitrary-and-unknown-skill-level"

then yes, I consider them to be extremely simple.


> >Tell me what this does:
> >
> >class Tree { 
> >      method bark() { die "Cannot instantiate a Tree--it is abstract!" }
> >}
> >class Birch { 
> >      method bark() { return "White, papery" }
> >}
> >class Oak { 
> >      method bark() { return "Dark, heavy" }
> >}
> >class Dog {
> >      method bark() { print "Woof, woof!"; return "bow wow" }
> >}
> 
> Four 'pure' classes so far.

Dog is not pure according to the definition of "pure class" that I
know (no side effects in any method, constructor, or subclass).  Maybe
'pure class' means something else to you?


> >class AlienBeastie isa Tree isa Dog {}
> 
> Here you get an error/warning of a composition time conflict between
> &Tree::bark and &Dog::bark. 

So that I'm clear, is this your opinion/preference or is it based on
material from the SEAs?  If the latter, could you point me to the
relevant passage?

> My preferred
> syntax for multiple inheritance is the junctive notation 'is Tree & Dog'
> for subclassing because it nicely allows for superclassing with
> 'is Tree | Dog'.

Again, so that I'm clear--this is your preference, and is not derived
from any authoritative source, correct?


> This might dispatch correctly for 'pure' Trees, Dogs etc.
> but not for your mixed classes above.

As I noted above, Dog is not 'pure' by the definition I know so I'm
not sure what to make of this statement.

--Dks

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