Re: Announce: Grace project site operational

[Simon Wright <simon@pushface.org>]

dennison@telepath.com (Ted Dennison) writes:

> Jeffrey Carter <jrcarter@acm.org> wrote in message news:<3CDD75C7.36C6ADCF@acm.org>...
> > The imported type Element should have the "=" operation imported for it.
> > 
> > The "=" operations for types List and Iterator should be visible to
> > clients of the package.
> 
> I'd like to see more discussion on this point. The way I remember it,
> we didn't want to add a lot of generic parameters that >%99 of the
> time would not be used. I can't remember overloading "=" myself, ever.
> This goes back to the "default generic parameters" issue, but I
> digress. However, I seem to remember some folks saying that not
> importing "=" this way causes the built-in equality to reassert itself
> even after its been overridden. Am I remembering this correctly?

I'm not so sure about "=" for Iterator. However, the BCs have users
who require Element to have overridden equality (and yes, you do need
to import, or default equality does reemerge).

The specific example was where equality only depended on some of the
fields (you could change other fields without affecting equality).

The same user wanted to be able to refefine equality for map Keys.