Feature gate: #![feature(refcell_try_map)]

This is a tracking issue for core::cell::{Ref,RefMut}::try_map

Public API

impl<'b, T> Ref<'b, T> {
    pub fn try_map<U: ?Sized, E>(
        orig: Ref<'b, T>,
        f: impl FnOnce(&T) -> Result<&U, E>,
    ) -> Result<Ref<'b, U>, (Self, E)> ;
}

impl<'b, T> RefMut<'b, T> {
    pub fn try_map<U: ?Sized, E>(
        mut orig: RefMut<'b, T>,
        f: impl FnOnce(&mut T) -> Result<&mut U, E>,
    ) -> Result<RefMut<'b, U>, (Self, E)>;
}

Steps / History

(Remember to update the S-tracking-* label when checking boxes.)

• Implementation: Add Ref/RefMut try_map method #118087
• First ACP: ACP: Add {Ref,RefMut}::try_map method  libs-team#341 (ignored by t-libs-api for 17 months)
• Second ACP: ACP: std::cell::{Ref,RefMut}::try_map libs-team#586 (accepted within 10 days, lol)
• Separate error type: refcell_try_map: add a separate error type #153093
• Expanding to cover more types: TBD
• Final comment period (FCP)¹
• Stabilization PR: Stabilize refcell_try_map #152092

Unresolved Questions

• None yet.