Hi there,
> On 17 Feb 2021, at 20:41, MG <[email protected]> wrote:
> Is telling the user that the Closure cannot be empty the only application for
> this ?
Not quite; the particular application is a bit complicated and not worth to
detail it here, but the gist is that my application offers a kind of API where
in some cases an empty “onerror” closure bears a meaning “I don't care of
errors if some happen”, and it would be nice if the core recognised that and
did not log these errors either.
Nevertheless, it's not a particularly good API, and I guess I'll think of a way
to improve it somehow, which would also get rid of a need for the
empty-closure-based hack, too :)
> On 17/02/2021 19:51, Daniel Sun wrote:
>> Groovy does not support checking empty closure at runtime AFAIK, but we
>> could check and set some property to closure while compiling, then get the
>> property at runtime.
Probably not worth implementing Groovy-side; if I really need that, I can
create an ASTT to do this at my side.
Thanks a lot!
OC
> If yes, given that a user can easily pass a non-empty but non-meaningful
> closure anyway I would question whether it is worth the effort.
>
> Cheers,
> mg
>
> PS: Also wondering whether we could achieve the same thing through the
> Closure return type, e.g.:
> @Test
> @Ignore
> void closureFooTest() {
> println closureFoo {}
> println closureFoo { "abc" }
> }
>
> def closureFoo(Closure<String> cls) {
> return "the string is: ${cls()}"
> }
> Should imho fail to compile, since an empty Closure should have return type
> void.
> Currently it does compile and run though (under 2.5.x) , even with
> @CompileStatic, since the empty closure implicitely returns null (imho one of
> the few bad design decisions in Groovy (whether in closures or somewhere
> else)), but at least IntelliJ marks it as invalid...
>
>
>
> On 17/02/2021 19:51, Daniel Sun wrote:
>> Groovy does not support checking empty closure at runtime AFAIK, but we
>> could check and set some property to closure while compiling, then get the
>> property at runtime. It will be an new improvement, not sure if others like
>> it or not.
>>
>> Cheers,
>> Daniel Sun
>>
>> On 2021/02/17 15:06:47, OCsite <[email protected]> <mailto:[email protected]> wrote:
>>> Hi there,
>>>
>>> is it possible to reliably recognise an empty closure, i.e., „{}“,
>>> programmatically?
>>>
>>> def foo(Closure bar) {
>>> if (?bar-is-empty?) throw new Exception('The closure cannot be empty!')
>>> else bar()
>>> }
>>> foo { println "ok" } // OK
>>> foo { 1 } // OK
>>> foo { } // throws
>>>
>>> Thanks!
>>> OC
>
