Fn traits for Rc and Arc #143Description
Proposal
Problem statement
It is not possible to pass reference-counted closures to APIs that take Fn + 'static or Fn + Clone.
Motivation, use-cases
Many server APIs expect 'static lifetimes but some logic may be implemented in a single closure that's reused in other places. Currently this would require moving captured values and invoking Clone on the closure itself, which clones captured values.
Solution sketches
impl<A, F: Fn<A> + ?Sized> Fn<A> for Rc<F>
impl<A, F: Fn<A> + ?Sized> FnMut<A> for Rc<F>
impl<A, F: Fn<A> + ?Sized> FnOnce<A> for Rc<F>
impl<A, F: Fn<A> + ?Sized> Fn<A> for Arc<F>
impl<A, F: Fn<A> + ?Sized> FnMut<A> for Arc<F>
impl<A, F: Fn<A> + ?Sized> FnOnce<A> for Arc<F>Alternative solutions: none.
Links and related work
Implementation: rust-lang/rust#105414
What happens now?
This issue is part of the libs-api team API change proposal process. Once this issue is filed the libs-api team will review open proposals in its weekly meeting. You should receive feedback within a week or two.