Tracking Issue for `debug_closure_helpers` · Issue #117729 · rust-lang/rust (original) (raw)

Feature gate: #![feature(debug_closure_helpers)]

This is a tracking issue for adding helpers to core::fmt that can use closures for formatting values.

// core::fmt

impl DebugList<'_, '_> { fn entry_with(&mut self, entry_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result; }

impl DebugMap<'_, '_> { fn key_with(&mut self, key_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result;

fn value_with(&mut self, value_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result; }

impl DebugSet<'_, '_> { fn entry_with(&mut self, entry_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result; }

impl DebugStruct<'_, '_> { fn field_with(&mut self, name: &str, field_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result; }

impl DebugTuple<'_, '_> { // also DebugSet fn field_with(&mut self, field_fmt: F) -> &mut Self where F: FnOnce(&mut Formatter) -> fmt::Result; }

pub from_fn(f: F) -> FromFn where F: Fn(&mut Formatter<'_>) -> Result { FormatterFn(f) }

pub struct FromFn(F) where F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result;

impl fmt::Debug for FromFn where F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result;

impl fmt::Display for FromFn where F: Fn(&mut fmt::Formatter<'_>) -> fmt::Result;

Naming: Do any strong preferences exist regarding the new method names?
- For now I've named them {orig_method}_with, for example DebugStruct::field_with() is like DebugStruct::field().
The DebugMap struct got key_with() and value_with(), but not entry_with() -- is it worth adding that?
Should FormatterFn<F> place a trait bound on F so that call sites can be tidier?

Tracking Issue for debug_closure_helpers · Issue #117729 · rust-lang/rust (original) (raw)