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https://github.com/haraldh/chainerror.git
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Harald Hoyer
cf62d1a9f9
Just use `#![doc = include_str!("../README.md")]`
Signed-off-by: Harald Hoyer <harald@hoyer.xyz>
112 lines
3.4 KiB
Markdown
112 lines
3.4 KiB
Markdown
[](https://crates.io/crates/chainerror)
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[](https://docs.rs/chainerror/)
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[](https://codecov.io/gh/haraldh/chainerror)
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# chainerror
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`chainerror` provides an error backtrace without doing a real backtrace, so even after you `strip` your
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binaries, you still have the error backtrace.
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Having nested function returning errors, the output doesn't tell where the error originates from.
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```rust
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use std::path::PathBuf;
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type BoxedError = Box<dyn std::error::Error + Send + Sync>;
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fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
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// do stuff, return other errors
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let _buf = std::fs::read_to_string(&path)?;
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// do stuff, return other errors
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Ok(())
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}
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fn process_config_file() -> Result<(), BoxedError> {
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// do stuff, return other errors
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let _buf = read_config_file("foo.txt".into())?;
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// do stuff, return other errors
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Ok(())
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}
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fn main() {
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if let Err(e) = process_config_file() {
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eprintln!("Error:\n{:?}", e);
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}
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}
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```
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This gives the output:
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```console
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Error:
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Os { code: 2, kind: NotFound, message: "No such file or directory" }
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```
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and you have no idea where it comes from.
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With `chainerror`, you can supply a context and get a nice error backtrace:
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```rust
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use chainerror::prelude::v1::*;
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use std::path::PathBuf;
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type BoxedError = Box<dyn std::error::Error + Send + Sync>;
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fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
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// do stuff, return other errors
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let _buf = std::fs::read_to_string(&path).context(format!("Reading file: {:?}", &path))?;
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// do stuff, return other errors
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Ok(())
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}
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fn process_config_file() -> Result<(), BoxedError> {
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// do stuff, return other errors
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let _buf = read_config_file("foo.txt".into()).context("read the config file")?;
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// do stuff, return other errors
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Ok(())
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}
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fn main() {
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if let Err(e) = process_config_file() {
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eprintln!("Error:\n{:?}", e);
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}
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}
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```
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with the output:
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```console
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Error:
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examples/simple.rs:14:51: read the config file
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Caused by:
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examples/simple.rs:7:47: Reading file: "foo.txt"
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Caused by:
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Os { code: 2, kind: NotFound, message: "No such file or directory" }
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```
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`chainerror` uses `.source()` of `std::error::Error` along with `#[track_caller]` and `Location` to provide a nice debug error backtrace.
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It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
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Along with the `ChainError<T>` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
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`chainerror` has no dependencies!
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Debug information is worth it!
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## Tutorial
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Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
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## License
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Licensed under either of
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* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or https://www.apache.org/licenses/LICENSE-2.0)
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* MIT license ([LICENSE-MIT](LICENSE-MIT) or https://opensource.org/licenses/MIT)
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at your option.
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### Contribution
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Unless you explicitly state otherwise, any contribution intentionally
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submitted for inclusion in the work by you, as defined in the Apache-2.0
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license, shall be dual licensed as above, without any additional terms or
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conditions.
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