Documentation of Project Coin features as implemented in the JDK 7 developer preview

[Maurizio Cimadamore]

On 09/03/11 14:30, Rémi Forax wrote:
> On 03/09/2011 03:17 PM, Maurizio Cimadamore wrote:
>> On 09/03/11 13:49, Eamonn McManus wrote:
>>>> So it is more a compiler bug erroneously accepting spaces 'inside' the
>>>> diamond. The compiler should be fixed.
>>> I don't understand this. We're not introducing a new lexical<>   token,
>>> are we? So obviously the compiler must allow spaces between<   and>,
>>> as between any pair of tokens. Stylistically, some people might prefer
>>> to write List<   Integer>, say, and would certainly be surprised not
>>> to be able to write List<   >.
>> I think it would be better if the compiler would be stricter about this,
>> and to deal with diamond as if it were a token - otherwise, programmer
>> might abuse of current behavior:
>>
>> new ArrayList<   >();
>>
>> new ArrayList<
>>    >();
>>
>> Which is ugly.
>>
>> Maurizio
> It's not fundamentally different from
> new ArrayList
> <>
> ();
> which is legal.
I see, so since the above is allowed, let's add a further level:

new ArrayList
<
>
();

:-)
> And considering<>  is a kind of new operator is weird.
>
I haven't used the 'operator' word once in my earlier emails.
> As Éamonn says new ArrayList<  String>  is legal so new ArrayList<  >
> should be legal.
As I said, I think that this argument can go both ways: one can think 
that diamond is special enough to deserve special treatement; on the 
other hand, one would like diamond to be uniform with standard type 
argument lists. In my opinion, the benefits of treating '<>' as a single 
token outweights the problems (at the end of the day, the only arguably 
sensible thing that you couldn't do is 'Foo< >' - note the space).

Said that, all this is speculation - as Ulf pointed out, the spec is 
explicitly allowing whitespaces inside diamonds (strange thing is that 
doesn't seem to allow other separators... but I think that needs to 
follow if '<' and '>' are separate tokens).

Maurizio
> Rémi
>
>>> Éamonn
>>>
>>> On 9/3/11 2:25 PM, Maurizio Cimadamore wrote:
>>>> On 09/03/11 12:57, Ulf Zibis wrote:
>>>>> Why do you allow whitespace between the "<" and">" of a diamond.
>>>> Good catch - I don't think this is a spec problem, as the grammar for
>>>> diamond is defined as follows in the latest draft:
>>>>
>>>> /TypeArgumentsOrDiamond:/
>>>>
>>>>            /TypeArguments/
>>>>
>>>>            |<||>|
>>>>
>>>>
>>>> So it is more a compiler bug erroneously accepting spaces 'inside' the
>>>> diamond. The compiler should be fixed.
>>>>
>>>> Maurizio
>>>>> Is whitespace allowed for ++ operator e.g.?
>>>>>
>>>>> -Ulf
>>>>>
>>>>>
>>>>> Am 09.03.2011 07:40, schrieb Joe Darcy:
>>>>>> Joe Darcy wrote:
>>>>>>> Hello.
>>>>>>>
>>>>>>> I've posted documentation of the semantics of the Project Coin
>>>>>>> features as implemented in the JDK 7 developer preview,  b130, at:
>>>>>>> http://cr.openjdk.java.net/~darcy/ProjectCoin/ProjectCoin-Documentation-v0.83.html
>>>>>>>
>>>>>>>
>>>>>>> Before sending in comments or questions about a feature to coin-dev,
>>>>>>> please read the discussion section after a feature.  Many design
>>>>>>> considerations are discussed in those sections.  Additionally, some
>>>>>>> known bugs in the current implementation are noted in the text.  In
>>>>>>> particular, javac in the JDK 7 developer preview erroneously accepts
>>>>>>> diamond combined with non-generic classes and accepts some uses of
>>>>>>> diamond with anonymous inner classes. These bugs will be corrected in
>>>>>>> future builds.
>>>>>>>
>>>>>>> Happy reading,
>>>>>>>
>>>>>>> -Joe
>>>>>> No comments from the coin-dev readership on the posted documentation?
>>>>>>
>>>>>> -Joe
>>>>>>
>>>>>>
>