> On 25 Oct 2017, at 19:01, John McCall <rjmcc...@apple.com> wrote:
>
>> On Oct 25, 2017, at 7:41 AM, David Hart via swift-evolution
>> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
>> I got bit again by a sneaky memory leak concerning local functions and would
>> like to discuss a small language change. I vaguely remember this being
>> discussed in the past, but can’t find the thread (if anybody could point me
>> to it, I’d appreciate it). Basically, here’s an example of the leak:
>>
>> class A {
>> func foo() {
>> func local() {
>> bar()
>> }
>>
>> methodWithEscapingClosure { [unowned self] _ in
>> self.bar()
>> local() // this leaks because local captures self
>> }
>> }
>>
>> func bar() {
>> }
>> }
>>
>> Its sneaky because local’s capturing of self is not obvious if you’ve
>> trained your brain to watch out for calls prefixed with self. I would
>> suggest having the compiler force users to make self capturing explicit, the
>> same way it does for closures:
>
> I think this is a good idea. Ideally the proposal would also allow explicit
> capture lists in local functions.
Ideally, yes. But the only sensible syntax I can come up for that seems odd in
the context of functions:
class A {
func foo() {
func local() -> Int { [weak self] in
}
}
}
Don’t you think?
David.
> John.
>
>>
>> class A {
>> func foo() {
>> func local() {
>> bar() // error: Call to method ‘bar' in function ‘local'
>> requires explicit 'self.' to make capture semantics explicit
>> }
>>
>> // ...
>> }
>> }
>>
>> What do you think?
>>
>> David.
>>
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>> swift-evolution@swift.org <mailto:swift-evolution@swift.org>
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>
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