Array

[Rémi Forax]

tronicek at fel.cvut.cz a écrit :
> { => } is not legal. Sorry. { => void }[] p = null; compiles right.
>
> Are the changes required to make array of generics safe described 
> anywhere?
no, i should write a blog.
>
> Z.
Rémi
>
> --Zdenek Tronicek
> Department of Computer Science and Engineering
> Prague                   tel: +420 2 2435 7410
> http://cs.felk.cvut.cz/~tronicek
>
>
> Quoting Rémi Forax <forax at univ-mlv.fr>:
>
>> tronicek at fel.cvut.cz a écrit :
>>> Hi,
>>>
>>> the compiler generates a warning when you call this method:
>>>
>>>    static { => String } concat({ => String }... arg) {
>>>        @Shared
>>>        String s = "";
>>>        for ({ => String } p : arg) {
>>>            s += p.invoke();
>>>        }
>>>        return { => s };
>>>    }
>>>
>>> It is because the compiler replaces the variable-length arguments  
>>> with arrays.
>>> E.g.
>>>
>>>    { => String } p3 = concat({ => "I" }, { => "like" }, { => 
>>> "closures" });
>>>
>>> will be transformed to:
>>>
>>>    { => String } p3 = concat(new javax.lang.function.O[] {{ => "I"  
>>> }, { => "like" }, { => "closures" }});
>>>
>>> And because javax.lang.function.O is a generic type, the compiler 
>>> complains.
>> yes, currently, function type are transformed to generics so you have
>> the same limitation.
>> By the way, Array of generics are not unsafe, the JLS require to emit
>> warning (or error)
>> but we found (with Alex Buckley) a way to make them safe.
>> This require to change the JLS and this is not backward compatible,
>> some warnings are removed
>> by some are added but i think it worth the change.
>>>
>>>
>>> Another thing:
>>>
>>> { => }[] p = null;
>> { => } is legal ?
>> is it equivalent to { => void } ??
>>>
>>> does not compile.
>>>
>>>
>>> Zdenek
>> Rémi
>>> --Zdenek Tronicek
>>> Department of Computer Science and Engineering
>>> Prague                   tel: +420 2 2435 7410
>>> http://cs.felk.cvut.cz/~tronicek
>>>
>>>
>>>
>>>
>>>
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