Re: light weight types
Roedy Green wrote:
& is used where you would expect to use comma. extends is used where
you would expect to use implements. super does not mean super.
I assume you're talking about something like
public class Foo
<T extends Collection<?> & Comparable<? super T>>
I don't know why you would expect a comma where '&' is used - that would be
incredibly ambiguous. Commas between type parameters represent different type
parameters, i.e., where more than one type is specified:
Map <T extends Foo, U extends Bar>
Replacing '&' in intersection types (and doesn't '&' communicate the idea of
"intersection" just perfectly?) with a comma would conflict with that usage.
Why would "implements" be better than "extends"? The supertype doesn't have
to be an interface. The idea of "extension" is much more natural for type
analysis than "implementation". Really, "implementation" is not at all a
natural concept for type analysis.
And how does "super" not mean super? The type that is "super" ('?' in the
example here) is a supertype; using "super" as the keyword seems entirely natural.
And why are we bitching about this five-year-old syntax anyway? It's a done
deal. Java already has generics defined the way Java already has generics
defined. It will be far, far more productive to learn the syntax than to try
to change it. Especially if the proposed changes are far, far less sensible
than the status quo.
--
Lew