Rust must-know libraries thiserror and anyhow

thiserror

Thiserror is a library for simplifying custom error type definitions, which provides a convenient derived macro for the standard library std :: error :: errortrait... Here are the main features and usage of thiserror.

To use thiserror, first add a dependency in Cargo.toml:

[dependencies] thiserror = "1.0"

Then, you can define an error type like this:

use thiserror::Error;#[derive(Error, Debug)]
pub enum MyError {
    #[error("IO error: {0}")]
    Io(#[from] std::io::Error),    #[error("Parse error: {0}")]
    Parse(#[from] std::num::ParseIntError),    #[error("Custom error: {msg}")]
    Custom { msg: String },
}

• #[derive (Error) ]: This derived macro automatically implements the std :: error :: Errortrait.
• #[error ("...") ]: Defines the format of the error message. Fields can be referenced using placeholders.
• If you provide a #[error (“…”) ] message on each variant of a struct or enumeration, a Displayimplementation is automatically generated.
• #[error ("{var}") ]corresponds to write !("{}", self.var)
• #[error ("{0}") ]corresponds to write !("{}", self.0)
• Formatted versions are also supported, such as #[error ("{var :?}")]
• #[From]: Automatically implements the Fromtrait, allowing conversions from other error types.