> On 31 Jan 2018, at 23.01, MG <[email protected]> wrote:
>
> Hi Jesper,
>
> seen from a Groovy user perspective your proposal seems to make sense to me.
> (I would at the same time hope you do not dent Daniel Sun's enthusiasm too
> much, because as far as I can tell he is currently doing alot of the heavy
> lifting in this project :-) )
>
Yes, he is - and the lambda work has come a long way - I'm testing some
scenarios, so i hope to lift a little, too!
> How do you think what you propose fares with regards to "the principle of
> least surprise" ? Are there any cases where this could lead to hard to track
> bugs / unexpected behavior ? From the top of my hat, that would be my biggest
> concern...
I see static and dynamic as different concerns: For dynamic invocation, there
could be some surprises, like example posted by 'avafanasiev' on GitHub:
class R implements Runnable { void run(){}}
def m(Runnable r1, R r2, r3) {
r1()
r2()
r3()
}
m(new R(), new R(), new R())
Currently, in the 'native-lambda' branch, r1() succeeds, whereas the latter two
fail to run/compile (depending on dynamic/static compilation), as 'avafanasiev'
commented on. I do find that confusing: Dynamically, my opinion is that the
three should work the same.
For static compilation, r1() and r2() should work IMHO, and r3() should be
rejected. This shouldn't surprise anyone, I think.
Also, surprise-wise,
class Q implements Runnable, Predicate<String> { void run(){}; boolean
test(String s) { s } }
def n(Runnable q1, Predicate<String> q2, Q q2, q3) {
r1()
r2()
r3()
}
m(new R(), new R(), new R())
> "...only as a fallback if obj.call doesn't exist" seems like the safer
> choice in this regard. Default behavior could also be made overridable by a
> class annotation (then it would become the programmer's responsibility, to
> make sure least surprise is not violated).
> Without that the question to me is: Would choosing "fallback if obj.call
> doesn't exist" weaken the elegance of the whole concept too much ?
>
> mg
>
>
> On 31.01.2018 10:00, Jesper Steen Møller wrote:
>> Hi list
>>
>> FYI: This turned into a discussion of the feature itself, on the GitHub
>> commit thread. Basically, I'm proposing changing what "obj(params...)" means:
>> - Non-SAM types: obj(params...) becomes obj.call(params...)
>> - SAM types: obj(params...) becomes obj.<sam-method>(params...) - perhaps
>> only as a fallback if obj.call doesn't exist.
>>
>> This should be completely independent of how the lambda object itself was
>> created.
>>
>> I realize this is a potentially breaking change, but isn't it also a nice
>> one?
>> Thoughts?
>>
>> -Jesper
>>
>>> On 31 Jan 2018, at 03.16, Daniel Sun <[email protected]> wrote:
>>>
>>> Hi Jesper,
>>>
>>> I think your suggestion is very nice and I've completed callable native
>>> lambda according to option 2 :-)
>>>
>>> Here is the related commit:
>>> https://github.com/apache/groovy/commit/c24c0b7e6a67dcdf277207d4261cfa6f2b55031f
>>>
>>> Cheers,
>>> Daniel.Sun
>>>
>>>
>>>
>>> --
>>> Sent from: http://groovy.329449.n5.nabble.com/Groovy-Dev-f372993.html
>>
>
