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:
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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