Module prelude 

A “prelude” module providing a collection of useful names, without causing compiler complaints about the ones you don’t use.

Provided names are:

• The core anyhow::Error type
• The core anyhow::Result type, which is Result<T, anyhow::Error>
• The anyhow! macro to create an Error value from a string-format expression
• The bail! macro: bail!(...) = return Err(anyhow!(...))
• The ensure! macro: ensure!(cond, err) = if !cond { bail!(err); }
• The atry! macro for annotated question-mark behavior
• The a_ok_or! macro for annotated, fallibale Option unwrapping
• Rust’s std::result::Result type aliased as StdResult for convenience

Macros

a_ok_or

“annotated ok_or” — like Option::ok_or_else()?, but with the ability to add extended context to the error. This yields an AnnotatedMessage as its error type.

anyhow

Construct an ad-hoc error from a string or existing non-anyhow error value.

atry

“Annotated try” — like try!, but with the ability to add extended context to the error message. This tries to provide a bit more syntactic sugar than anyhow’s with_context(), and it supports our AnnotatedMessage context type.

bail

Return early with an error.

ensure

Return early with an error if a condition is not satisfied.

Structs

Error

The Error type, a wrapper around a dynamic error type.

Enums

StdResult

Result is a type that represents either success (Ok) or failure (Err).

Type Aliases

Result

Result<T, Error>