Proposal: Improved Wildcard Syntax for Java
howard.lovatt at iee.org
Tue Mar 17 17:54:56 PDT 2009
Thanks for the response, answers in text.
2009/3/18 Joseph D. Darcy <Joe.Darcy at sun.com> wrote:
>> 1. Deprecate raw declarations, new ArrayList() becomes a deprecated
>> warning - you need to say new ArrayList<Object>().
> That could be a fine lint option. You could also write an annotation
> processor that used the javac tree API to generated such warnings/errors
Yes you could - but I think it would be better in the language so that
every implementation gets this useful behaviour.
>> 2a. Deprecate self references, you get a deprecated warning for class
>> Type<T extends Type<T>>, you wouldn't use generics in this case.
> F-bounds are part of Java's generics.
Yes. But I am suggesting that we deprecate it because no one likes it.
The complication and confusion that it brings outweighs its benefit.
Less is more.
>> 3. Deprecate the ability to specify multiple bounds, e.g. instead of
>> static <T extends Object & Comparable<? super T>> T max(Collection<?
>> extends T>) you write static <Comparable T> T max(Collection<T>) (note
>> Comparable would not be parameterised with the new syntax since you
>> would almost always want Comparable<Object>).
> There are reasons why multiple bounds are supported.
Yes. Again not worth the trouble - don't use generics in these
backward compatibility cases. Typically you want Object - just use
Object, no generics. Same argument as deprecating F-bounds, less is
> If you want a proposal formally considered, you must fill out a proposal
Happy to do this if there is some support, not much point spending the
time if it is just going to be rejected outright. By some support I
don't mean a guarantee that it will make it into 7, but I do mean that
people who have a vote in this process (you, who else?) think it is
worth considering and within scope for coin.
>> So I am proposing eventually removing something from the language
>> (actually replacing) - is removing a feature a first on coin-dev?
> However, the proposal form explicitly disallows removing features "The
> proposal must not remove existing features of the language...".
That was more a flippant comment at the end of the email, I am
proposing deprecating features (warning issued) - not removing them.
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