JDK 8 code review request for 8005298 Add FunctionalInterface type to the core libraries

[Peter Levart]

On 01/16/2013 05:58 PM, Joe Darcy wrote:
> On 1/16/2013 8:32 AM, Florian Weimer wrote:
>> On 01/16/2013 05:27 PM, Brian Goetz wrote:
>>
>>> The primary purpose of this annotation is to *capture design 
>>> intent*.  It is not required.  The compiler will help you enforce 
>>> the design intent if you provide it.  The compiler will not 
>>> synthesize this annotation, since that would be guessing at the 
>>> design intent.  It is possible to create classfiles that subvert the 
>>> design intent.
>>>
>>> The point about other languages was simply to point out that the 
>>> universe of tools that might usefully use this design intent is 
>>> bigger than sometimes assumed.
>>
>> I don't think run-time behavior should depend on optional annotations 
>> documenting design intent (like @Override).
>>
>> Supporting the discovery of functional interfaces is a good idea. But 
>> a method like Class#isFunctionalInterface() would sever this purpose 
>> better than an entirely optional annotation.
>>
>
> A method like Class#isFunctionalInterface is planned too for later in 
> JDK 8.
I can imagine that a method like that would be useful if also 
accompanied with a method like:

Class#getFunctionalInterfaceMethod()

Regards, Peter

>
> -Joe