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//! Functionalities for implementing trackable errors and operating on those. //! //! You can easily define your own trackable error types as follows: //! //! ``` //! #[macro_use] //! extern crate trackable; //! use trackable::error::{TrackableError, ErrorKind, ErrorKindExt}; //! //! #[derive(Debug, TrackableError)] //! #[trackable(error_kind = "MyErrorKind")] //! struct MyError(TrackableError<MyErrorKind>); //! impl From<std::io::Error> for MyError { //! fn from(f: std::io::Error) -> Self { //! // Any I/O errors are considered critical //! MyErrorKind::Critical.cause(f).into() //! } //! } //! //! # #[allow(dead_code)] //! #[derive(Debug, PartialEq, Eq)] //! enum MyErrorKind { //! Critical, //! NonCritical, //! } //! impl ErrorKind for MyErrorKind {} //! //! fn main() { //! // Tracks an error //! let error: MyError = MyErrorKind::Critical.cause("something wrong").into(); //! let error = track!(error); //! let error = track!(error, "I passed here"); //! assert_eq!(format!("\nError: {}", error).replace('\\', "/"), r#" //! Error: Critical (cause; something wrong) //! HISTORY: //! [0] at src/error.rs:27 //! [1] at src/error.rs:28 -- I passed here //! "#); //! //! // Tries to execute I/O operation //! let result = (|| -> Result<_, MyError> { //! let f = track!(std::fs::File::open("/path/to/non_existent_file") //! .map_err(MyError::from))?; //! Ok(f) //! })(); //! let error = result.err().unwrap(); //! let cause = error.concrete_cause::<std::io::Error>().unwrap(); //! assert_eq!(cause.kind(), std::io::ErrorKind::NotFound); //! } //! ``` //! //! # `TrackableError` drive macro //! //! If it is specified (i.e., `#[derive(TrackableError)]`), //! the following traits will be automatically implemented in the target error type: //! - `Trackable` //! - `Error` //! - `Display` //! - `Deref<Target = TrackableError<$error_kind>>` //! - `From<$error_kind>` //! - `From<TrackableError<$error_kind>>` //! - `From<$target_error_type> for TrackableError<$error_kind>` //! //! The default value of `$error_kind` is `ErrorKind`. //! It can be customized by using `#[trackable(error_type = "$error_kind")]` attribute. //! //! The target error type must be a newtype (i.e., a tuple struct that has a single element) of `TrackableError`. use std::error::Error; use super::Location; /// Boxed `Error` object. pub type BoxError = Box<dyn Error + Send + Sync>; /// Boxed `ErrorKind` object. pub type BoxErrorKind = Box<dyn ErrorKind + Send + Sync>; /// `History` type specialized for `TrackableError`. pub type History = ::History<Location>; pub use trackable1::error::Failed; pub use trackable1::error::Failure; pub use trackable1::error::IoError; /// An `Error` type for unit tests. pub type TestError = TopLevelError; /// An `Error` type for `main` function. pub type MainError = TopLevelError; pub use trackable1::error::TopLevelError; pub use trackable1::error::ErrorKind; pub use trackable1::error::ErrorKindExt; pub use trackable1::error::TrackableError; #[cfg(test)] mod test { use super::*; use std; #[test] fn it_works() { #[derive(Debug, TrackableError)] #[trackable(error_kind = "MyErrorKind")] struct MyError(TrackableError<MyErrorKind>); impl From<std::io::Error> for MyError { fn from(f: std::io::Error) -> Self { // Any I/O errors are considered critical MyErrorKind::Critical.cause(f).into() } } #[allow(dead_code)] #[derive(Debug, PartialEq, Eq)] enum MyErrorKind { Critical, NonCritical, } impl ErrorKind for MyErrorKind {} // Tracks an error let error: MyError = MyErrorKind::Critical.cause("something wrong").into(); let error = track!(error); let error = track!(error, "I passed here"); assert_eq!( format!("\nError: {}", error).replace('\\', "/"), r#" Error: Critical (cause; something wrong) HISTORY: [0] at src/error.rs:128 [1] at src/error.rs:129 -- I passed here "# ); // Tries to execute I/O operation let result = (|| -> Result<_, MyError> { let f = track!(std::fs::File::open("/path/to/non_existent_file").map_err(MyError::from,))?; Ok(f) })(); let error = result.err().unwrap(); let cause = error.concrete_cause::<std::io::Error>().unwrap(); assert_eq!(cause.kind(), std::io::ErrorKind::NotFound); } }