Tracking Issue for `debug_closure_helpers` (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<F>(&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; }

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().
- Resolved: The FormatterFn type was renamed to FromFn (and wrapped in from_fn(), the helper methods kept their original names.
The DebugMap struct got key_with() and value_with(), but not entry_with() -- is it worth adding that?
- Resolved to not add entry_with; see Replace Debug::{key_with, value_with} with DebugMap::entry_with libs-team#563 (comment)
Should FormatterFn<F> place a trait bound on F so that call sites can be tidier?

Tracking Issue for debug_closure_helpers (original) (raw)