thiserror 和 anyhow

The thiserror and anyhow crates are widely used to simplify error handling.

  • thiserror is often used in libraries to create custom error types that implement From<T>.
  • anyhow is often used by applications to help with error handling in functions, including adding contextual information to your errors.
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Speaker Notes

 This slide should take about 5 minutes.

thiserror

  • The Error derive macro is provided by thiserror, and has lots of useful attributes to help define error types in a compact way.
  • The std::error::Error trait is derived automatically.
  • The message from #[error] is used to derive the Display trait.

anyhow

  • anyhow::Error is essentially a wrapper around Box<dyn Error>. As such it’s again generally not a good choice for the public API of a library, but is widely used in applications.
  • anyhow::Result<V> is a type alias for Result<V, anyhow::Error>.
  • Actual error type inside of it can be extracted for examination if necessary.
  • Functionality provided by anyhow::Result<T> may be familiar to Go developers, as it provides similar usage patterns and ergonomics to (T, error) from Go.
  • anyhow::Context is a trait implemented for the standard Result and Option types. use anyhow::Context is necessary to enable .context() and .with_context() on those types.