Crate displaydoc[][src]

This library provides a convenient derive macro for the standard library’s core::fmt::Display trait.

displaydoc = "0.2"

Compiler support: requires rustc 1.31+


use std::io;
use displaydoc::Display;
use thiserror::Error;

#[derive(Display, Error, Debug)]
pub enum DataStoreError {
    /// data store disconnected
    Disconnect(#[source] io::Error),
    /// the data for key `{0}` is not available
    /// invalid header (expected {expected:?}, found {found:?})
    InvalidHeader {
        expected: String,
        found: String,
    /// unknown data store error


  • A Display impl is generated for your type if you provide doc comment messages on the struct or each variant of your enum, as shown above in the example.

    The messages support a shorthand for interpolating fields from the error.

    • /// {var}write!("{}", self.var)
    • /// {0}write!("{}", self.0)
    • /// {var:?}write!("{:?}", self.var)
    • /// {0:?}write!("{:?}", self.0)


  1. Is this crate no_std compatible?

    • Yes! This crate implements the core::fmt::Display trait not the std::fmt::Display trait so it should work in std and no_std environments. Just add default-features = false.
  2. Does this crate work with Path and PathBuf via the Display trait?

    • Yuuup. This crate uses @dtolnay’s autoref specialization technique to add a special trait for types to get the display impl, it then specializes for Path and PathBuf and when either of these types are found it calls self.display() to get a std::path::Display<'_> type which can be used with the Display format specifier!

Derive Macros


Derive macro for implementing Display via doc comment attributes