refactor: simplify downcasting logic with std::mem::transmute (#20)

Simplified the downcasting implementations by replacing pointer casting
logic with `std::mem::transmute`, ensuring type safety after matching.
Added tests to validate various downcasting behaviors for both owned and
trait-object error scenarios, improving overall reliability and test
coverage.

.github/workflows/coverage.yml

@@ -13,31 +13,26 @@ on:
     types:
       - created
 
+
 jobs:
-  test:
-    name: coverage
+  coverage:
     runs-on: ubuntu-latest
+    env:
+      CARGO_TERM_COLOR: always
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@v4
       - uses: dtolnay/rust-toolchain@master
         with:
           target: x86_64-unknown-linux-gnu
           toolchain: nightly
           components: llvm-tools-preview
-
       - name: Install cargo-llvm-cov
-        run: >
-          curl -LsSf 'https://github.com/taiki-e/cargo-llvm-cov/releases/download/v0.5.23/cargo-llvm-cov-x86_64-unknown-linux-musl.tar.gz'
-          | tar xzf -
-          && mv cargo-llvm-cov $HOME/.cargo/bin
-
-      - name: Run cargo-llvm-cov
-        run: cargo llvm-cov --doctests --all --all-features --lcov --output-path lcov.info
-
+        uses: taiki-e/install-action@cargo-llvm-cov
+      - name: Generate code coverage
+        run: cargo +nightly llvm-cov --all-features --workspace --codecov --doctests --output-path codecov.json
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v3
         with:
-          directory: ./
-          fail_ci_if_error: false
-          files: ./lcov.info
-          verbose: true
+          token: ${{ secrets.CODECOV_TOKEN }} # not required for public repos
+          files: codecov.json
+          fail_ci_if_error: true

.github/workflows/gh-pages.yml

@@ -7,7 +7,7 @@ on:
 
 jobs:
   deploy:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
 

.github/workflows/rust.yml

@@ -19,7 +19,7 @@ jobs:
     strategy:
       matrix:
         version:
-          - 1.46.0
+          - 1.54.0
           - stable
           - beta
           - nightly
@@ -70,16 +70,3 @@ jobs:
         with:
           command: clippy
           args: -- -D warnings
-
-  readme:
-    name: cargo readme
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v2
-      - uses: dtolnay/rust-toolchain@master
-        with:
-          toolchain: stable
-          profile: minimal
-          override: true
-      - run: cargo install cargo-readme
-      - run: cargo readme > README.md && git diff --exit-code

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "chainerror"
-version = "0.7.1"
+version = "1.0.0"
 authors = ["Harald Hoyer <harald@redhat.com>"]
 edition = "2018"
 license = "MIT OR Apache-2.0"
@@ -22,6 +22,5 @@ maintenance = { status = "actively-developed" }
 is-it-maintained-issue-resolution = { repository = "haraldh/chainerror" }
 is-it-maintained-open-issues = { repository = "haraldh/chainerror" }
 
-[features]
-default = []
-display-cause = []
+[package.metadata.docs.rs]
+cargo-args = ["-Zunstable-options", "-Zrustdoc-scrape-examples"]

README.md

@@ -1,9 +1,6 @@
 [![Crate](https://img.shields.io/crates/v/chainerror.svg)](https://crates.io/crates/chainerror)
 [![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/chainerror/)
-[![Coverage Status](https://coveralls.io/repos/github/haraldh/chainerror/badge.svg?branch=master)](https://coveralls.io/github/haraldh/chainerror?branch=master)
-[![Workflow Status](https://github.com/haraldh/chainerror/workflows/Rust/badge.svg)](https://github.com/haraldh/chainerror/actions?query=workflow%3A%22Rust%22)
-[![Average time to resolve an issue](https://isitmaintained.com/badge/resolution/haraldh/chainerror.svg)](https://isitmaintained.com/project/haraldh/chainerror "Average time to resolve an issue")
-[![Percentage of issues still open](https://isitmaintained.com/badge/open/haraldh/chainerror.svg)](https://isitmaintained.com/project/haraldh/chainerror "Percentage of issues still open")
+[![Coverage Status](https://codecov.io/gh/haraldh/chainerror/branch/master/graph/badge.svg?token=HGLJFGA11B)](https://codecov.io/gh/haraldh/chainerror)
 ![Maintenance](https://img.shields.io/badge/maintenance-activly--developed-brightgreen.svg)
 
 # chainerror
@@ -49,7 +46,7 @@ and you have no idea where it comes from.
 With `chainerror`, you can supply a context and get a nice error backtrace:
 
 ```rust
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
 use std::path::PathBuf;
 
 type BoxedError = Box<dyn std::error::Error + Send + Sync>;
@@ -87,16 +84,86 @@ Os { code: 2, kind: NotFound, message: "No such file or directory" }
 `chainerror` uses `.source()` of `std::error::Error` along with `#[track_caller]` and `Location` to provide a nice debug error backtrace.
 It encapsulates all types, which have `Display + Debug` and can store the error cause internally.
 
-Along with the `ChainError<T>` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
+Along with the `Error<T>` struct, `chainerror` comes with some useful helper macros to save a lot of typing.
 
 `chainerror` has no dependencies!
 
 Debug information is worth it!
 
-### Features
+## Multiple Output Formats
 
-`display-cause`
-: turn on printing a backtrace of the errors in `Display`
+`chainerror` supports multiple output formats, which can be selected with the different format specifiers:
+
+* `{}`: Display
+```console
+func1 error calling func2
+```
+
+* `{:#}`: Alternative Display
+```console
+func1 error calling func2
+Caused by:
+  func2 error: calling func3
+Caused by:
+  (passed error)
+Caused by:
+  Error reading 'foo.txt'
+Caused by:
+  entity not found
+```
+
+* `{:?}`: Debug
+```console
+examples/example.rs:50:13: func1 error calling func2
+Caused by:
+examples/example.rs:25:13: Func2Error(func2 error: calling func3)
+Caused by:
+examples/example.rs:18:13: (passed error)
+Caused by:
+examples/example.rs:13:18: Error reading 'foo.txt'
+Caused by:
+Kind(NotFound)
+
+```
+
+* `{:#?}`: Alternative Debug
+```console
+Error<example::Func1Error> {
+    occurrence: Some(
+        "examples/example.rs:50:13",
+    ),
+    kind: func1 error calling func2,
+    source: Some(
+        Error<example::Func2Error> {
+            occurrence: Some(
+                "examples/example.rs:25:13",
+            ),
+            kind: Func2Error(func2 error: calling func3),
+            source: Some(
+                Error<chainerror::AnnotatedError> {
+                    occurrence: Some(
+                        "examples/example.rs:18:13",
+                    ),
+                    kind: (passed error),
+                    source: Some(
+                        Error<alloc::string::String> {
+                            occurrence: Some(
+                                "examples/example.rs:13:18",
+                            ),
+                            kind: "Error reading 'foo.txt'",
+                            source: Some(
+                                Kind(
+                                    NotFound,
+                                ),
+                            ),
+                        },
+                    ),
+                },
+            ),
+        },
+    ),
+}
+```
 
 ## Tutorial
 
@@ -106,8 +173,8 @@ Read the [Tutorial](https://haraldh.github.io/chainerror/tutorial1.html)
 
 Licensed under either of
 
-* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or https://www.apache.org/licenses/LICENSE-2.0)
-* MIT license ([LICENSE-MIT](LICENSE-MIT) or https://opensource.org/licenses/MIT)
+* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <https://www.apache.org/licenses/LICENSE-2.0>)
+* MIT license ([LICENSE-MIT](LICENSE-MIT) or <https://opensource.org/licenses/MIT>)
 
 at your option.
 

README.tpl

@@ -1,24 +0,0 @@
-[![Crate](https://img.shields.io/crates/v/chainerror.svg)](https://crates.io/crates/chainerror)
-[![Rust Documentation](https://img.shields.io/badge/api-rustdoc-blue.svg)](https://docs.rs/chainerror/)
-[![Coverage Status](https://coveralls.io/repos/github/haraldh/chainerror/badge.svg?branch=master)](https://coveralls.io/github/haraldh/chainerror?branch=master)
-{{badges}}
-
-# {{crate}}
-
-{{readme}}
-
-## License
-
-Licensed under either of
-
-* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or https://www.apache.org/licenses/LICENSE-2.0)
-* MIT license ([LICENSE-MIT](LICENSE-MIT) or https://opensource.org/licenses/MIT)
-
-at your option.
-
-### Contribution
-
-Unless you explicitly state otherwise, any contribution intentionally
-submitted for inclusion in the work by you, as defined in the Apache-2.0
-license, shall be dual licensed as above, without any additional terms or
-conditions.

booksrc/LICENSE-APACHE

@@ -0,0 +1 @@
+../LICENSE-APACHE

booksrc/LICENSE-MIT

@@ -0,0 +1 @@
+../LICENSE-MIT

booksrc/tutorial10.md

@@ -1,6 +1,6 @@
 # ErrorKind to the rescue
 
-To cope with different kind of errors, we introduce the kind of an error `Func1ErrorKind` with an enum.
+To cope with different kind of errors, we introduce the `kind` of an error `Func1ErrorKind` with an enum.
 
 Because we derive `Debug` and implement `Display` our `Func1ErrorKind` enum, this enum can be used as
 a `std::error::Error`.
@@ -8,10 +8,9 @@ a `std::error::Error`.
 Only returning `Func1ErrorKind` in `func1()` now let us get rid of `Result<(), Box<Error + Send + Sync>>` and we can
 use `ChainResult<(), Func1ErrorKind>`.
 
-In `main` we can now directly use the methods of `ChainError<T>` without downcasting the error first.
+In `main` we can now directly use the methods of `chainerror::Error<T>` without downcasting the error first.
 
-Also a nice `match` on `ChainError<T>.kind()` is now possible, which returns `&T`, meaning 
-`&Func1ErrorKind` here.
+Also, a nice `match` on `chainerror::Error<T>.kind()` is now possible, which returns `&T`, meaning `&Func1ErrorKind` here.
 
 ~~~rust
 {{#include ../examples/tutorial10.rs}}

booksrc/tutorial11.md

@@ -21,7 +21,7 @@ which gives us a lot more detail.
 
 To create your own Errors, you might find [crates](https://crates.io) which create enum `Display+Debug` via derive macros.
 
-Also noteworthy is [custom_error](https://crates.io/crates/custom_error) to define your custom errors,
+Also, noteworthy is [custom_error](https://crates.io/crates/custom_error) to define your custom errors,
 which can then be used with `chainerror`.
 
 ~~~rust

booksrc/tutorial12.md

@@ -1,6 +1,6 @@
 # Deref for the ErrorKind
 
-Because ChainError<T> implements Deref to &T, we can also match on `*e` instead of `e.kind()`
+Because chainerror::Error<T> implements Deref to &T, we can also match on `*e` instead of `e.kind()`
 or call a function with `&e`
 ~~~rust
 {{#include ../examples/tutorial12.rs}}

booksrc/tutorial13.md

@@ -1,6 +1,6 @@
 # Writing a library
 
-I would advise to only expose an `mycrate::ErrorKind` and type alias `mycrate::Error` to `ChainError<mycrate::ErrorKind>`
+I would advise to only expose an `mycrate::ErrorKind` and type alias `mycrate::Error` to `chainerror::Error<mycrate::ErrorKind>`
 so you can tell your library users to use the `.kind()` method as `std::io::Error` does.
 
 If you later decide to make your own `Error` implementation, your library users don't

booksrc/tutorial2.md

@@ -25,7 +25,7 @@ along with the `Location` of the `context()` call and returns `Err(newerror)`.
 `?` then returns the inner error applying `.into()`, so that we
 again have a `Err(Box<Error + Send + Sync>)` as a result.
 
-The `Debug` implementation of `ChainError<T>` (which is returned by `context()`)
+The `Debug` implementation of `chainerror::Error<T>` (which is returned by `context()`)
 prints the `Debug` of `T` prefixed with the stored filename and line number.
 
-`ChainError<T>` in our case is `ChainError<&str>`.
+`chainerror::Error<T>` in our case is `chainerror::Error<&str>`.

booksrc/tutorial3.md

@@ -14,13 +14,13 @@ If you compare the output to the previous example, you will see,
 that:
 
 ~~~
-Error: src/main.rs:19: "func1 error"
+Error: examples/tutorial2.rs:20:16: func1 error
 ~~~
 
 changed to just:
 
 ~~~
-src/main.rs:16: "func1 error"
+examples/tutorial3.rs:17:13: func1 error
 ~~~
 
 This is, because we caught the error of `func1()` in `main()` and print it out ourselves.

booksrc/tutorial5.md

@@ -14,5 +14,4 @@ Sometimes you want to inspect the `source()` of an `Error`.
 Note, that because we changed the output of the error in `main()` from 
 `Debug` to `Display`, we don't see the error backtrace with filename and line number.
 
-To enable the `Display` backtrace, you have to enable the feature `display-cause` for `chainerror`.
- 
+To use the `Display` backtrace, you have to use the alternative display format output `{:#}`.

booksrc/tutorial7.md

@@ -4,15 +4,15 @@
 
 ~~~rust,ignore
 fn is_chain<T: 'static + Display + Debug>(&self) -> bool
-fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&ChainError<T>>
-fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut ChainError<T>>
+fn downcast_chain_ref<T: 'static + Display + Debug>(&self) -> Option<&chainerror::Error<T>>
+fn downcast_chain_mut<T: 'static + Display + Debug>(&mut self) -> Option<&mut chainerror::Error<T>>
 fn root_cause(&self) -> Option<&(dyn Error + 'static)>
 fn find_cause<U: Error + 'static>(&self) -> Option<&U>
-fn find_chain_cause<U: Error + 'static>(&self) -> Option<&ChainError<U>>
+fn find_chain_cause<U: Error + 'static>(&self) -> Option<&chainerror::Error<U>>
 fn kind<'a>(&'a self) -> &'a T
 ~~~
 
-Using `downcast_chain_ref::<String>()` gives a `ChainError<String>`, which can be used
+Using `downcast_chain_ref::<String>()` gives a `chainerror::Error<String>`, which can be used
 to call `.find_cause::<io::Error>()`. 
 
 ~~~rust,ignore

booksrc/tutorial8.md

@@ -1,14 +1,14 @@
 # Finding an Error cause
 
-To distinguish the errors occuring in various places, we can define named string errors with the
+To distinguish the errors occurring in various places, we can define named string errors with the
 "new type" pattern.
 
 ~~~rust,ignore
-derive_str_context!(Func2Error);
-derive_str_context!(Func1Error);
+chainerror::str_context!(Func2Error);
+chainerror::str_context!(Func1Error);
 ~~~
 
-Instead of `ChainError<String>` we now have `struct Func1Error(String)` and `ChainError<Func1Error>`.
+Instead of `chainerror::Error<String>` we now have `struct Func1Error(String)` and `chainerror::Error<Func1Error>`.
 
 In the `main` function you can see, how we can match the different errors.
 
@@ -18,9 +18,9 @@ Also see:
 ~~~
 as a shortcut to
 ~~~rust,ignore
-            if let Some(f2err) = f1err.find_cause::<ChainError<Func2Error>>() {
+            if let Some(f2err) = f1err.find_cause::<chainerror::Error<Func2Error>>() {
 ~~~
-hiding the `ChainError<T>` implementation detail.
+hiding the `chainerror::Error<T>` implementation detail.
 
 ~~~rust
 {{#include ../examples/tutorial8.rs}}

examples/example.rs

@@ -1,24 +1,28 @@
+use chainerror::Context as _;
 use std::error::Error;
+use std::fmt;
 use std::io;
-use std::result::Result;
-
-use chainerror::prelude::v1::*;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-fn func3() -> Result<(), Box<dyn Error + Send + Sync>> {
+fn func4() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
     do_some_io().context(format!("Error reading '{}'", filename))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+fn func3() -> Result<(), Box<dyn Error + Send + Sync>> {
+    func4().annotate()?;
+    Ok(())
+}
 
-fn func2() -> ChainResult<(), Func2Error> {
-    func3().context(Func2Error("func2 error: calling func3".to_string()))?;
+chainerror::str_context!(Func2Error);
+
+fn func2() -> chainerror::Result<(), Func2Error> {
+    func3().context(Func2Error::new("func2 error: calling func3"))?;
     Ok(())
 }
 
@@ -27,8 +31,8 @@ enum Func1Error {
     IO(String),
 }
 
-impl ::std::fmt::Display for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+impl fmt::Display for Func1Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Func1Error::Func2 => write!(f, "func1 error calling func2"),
             Func1Error::IO(filename) => write!(f, "Error reading '{}'", filename),
@@ -36,13 +40,13 @@ impl ::std::fmt::Display for Func1Error {
     }
 }
 
-impl ::std::fmt::Debug for Func1Error {
-    fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
+impl fmt::Debug for Func1Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         write!(f, "{}", self)
     }
 }
 
-fn func1() -> ChainResult<(), Func1Error> {
+fn func1() -> chainerror::Result<(), Func1Error> {
     func2().context(Func1Error::Func2)?;
     let filename = String::from("bar.txt");
     do_some_io().context(Func1Error::IO(filename))?;
@@ -51,6 +55,10 @@ fn func1() -> ChainResult<(), Func1Error> {
 
 fn main() {
     if let Err(e) = func1() {
+        eprintln!("\nDisplay Error {{}}:\n{}", e);
+
+        eprintln!("\nAlternative Display Error {{:#}}:\n{:#}", e);
+
         eprintln!("\nDebug Error {{:?}}:\n{:?}", e);
 
         eprintln!("\nAlternative Debug Error {{:#?}}:\n{:#?}\n", e);

examples/tutorial1.rs

@@ -1,6 +1,8 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial10.rs

@@ -1,14 +1,14 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+chainerror::str_context!(Func2Error);
 
 fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
@@ -32,7 +32,7 @@ impl ::std::fmt::Display for Func1ErrorKind {
 }
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
     func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
     do_some_io().context(Func1ErrorKind::IO(filename))?;

examples/tutorial11.rs

@@ -1,14 +1,14 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+chainerror::str_context!(Func2Error);
 
 fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
@@ -38,7 +38,7 @@ impl ::std::fmt::Debug for Func1ErrorKind {
 
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
     func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
     do_some_io().context(Func1ErrorKind::IO(filename))?;

examples/tutorial12.rs

@@ -1,14 +1,14 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+chainerror::str_context!(Func2Error);
 
 fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
@@ -38,7 +38,7 @@ impl ::std::fmt::Debug for Func1ErrorKind {
 
 impl ::std::error::Error for Func1ErrorKind {}
 
-fn func1() -> ChainResult<(), Func1ErrorKind> {
+fn func1() -> chainerror::Result<(), Func1ErrorKind> {
     func2().context(Func1ErrorKind::Func2)?;
     let filename = String::from("bar.txt");
     do_some_io().context(Func1ErrorKind::IO(filename))?;

examples/tutorial13.rs

@@ -1,5 +1,9 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 pub mod mycrate {
-    use chainerror::prelude::v1::*;
+    use chainerror::Context as _;
+
     use std::io;
 
     fn do_some_io() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
@@ -7,7 +11,7 @@ pub mod mycrate {
         Ok(())
     }
 
-    derive_str_context!(Func2Error);
+    chainerror::str_context!(Func2Error);
 
     fn func2() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
         let filename = "foo.txt";
@@ -21,7 +25,7 @@ pub mod mycrate {
         IO(String),
     }
 
-    derive_err_kind!(Error, ErrorKind);
+    chainerror::err_kind!(Error, ErrorKind);
 
     pub type Result<T> = std::result::Result<T, Error>;
 

examples/tutorial14.rs

@@ -1,3 +1,6 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 pub mod mycrate {
     use std::error::Error as StdError;
 

examples/tutorial15.rs

@@ -1,5 +1,9 @@
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
 pub mod mycrate {
-    use chainerror::prelude::v1::*;
+    use chainerror::{Context as _, ErrorDown as _};
+
     use std::io;
 
     fn do_some_io(_f: &str) -> std::result::Result<(), io::Error> {
@@ -7,7 +11,7 @@ pub mod mycrate {
         Ok(())
     }
 
-    derive_str_context!(Func2Error);
+    chainerror::str_context!(Func2Error);
 
     fn func2() -> std::result::Result<(), Box<dyn std::error::Error + Send + Sync>> {
         let filename = "foo.txt";
@@ -23,7 +27,7 @@ pub mod mycrate {
         Unknown,
     }
 
-    derive_err_kind!(Error, ErrorKind);
+    chainerror::err_kind!(Error, ErrorKind);
     pub type Result<T> = std::result::Result<T, Error>;
 
     impl std::fmt::Display for ErrorKind {

examples/tutorial2.rs

@@ -1,8 +1,7 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
 
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial3.rs

@@ -1,8 +1,7 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
 
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial4.rs

@@ -1,7 +1,7 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial5.rs

@@ -1,7 +1,7 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial6.rs

@@ -1,7 +1,10 @@
-use chainerror::prelude::v1::*;
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+use chainerror::Context as _;
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial7.rs

@@ -1,7 +1,10 @@
-use chainerror::prelude::v1::*;
+#![allow(clippy::single_match)]
+#![allow(clippy::redundant_pattern_matching)]
+
+use chainerror::{Context as _, ErrorDown as _};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;

examples/tutorial8.rs

@@ -1,14 +1,14 @@
-use chainerror::prelude::v1::*;
+use chainerror::{Context as _, ErrorDown as _};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+chainerror::str_context!(Func2Error);
 
 fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
@@ -16,10 +16,10 @@ fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     Ok(())
 }
 
-derive_str_context!(Func1Error);
+chainerror::str_context!(Func1Error);
 
 fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
-    func2().context(Func1Error("func1 error".to_string()))?;
+    func2().context(Func1Error::new("func1 error"))?;
     Ok(())
 }
 
@@ -28,7 +28,7 @@ fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
         if let Some(f1err) = e.downcast_chain_ref::<Func1Error>() {
             eprintln!("Func1Error: {}", f1err);
 
-            if let Some(f2err) = f1err.find_cause::<ChainError<Func2Error>>() {
+            if let Some(f2err) = f1err.find_cause::<chainerror::Error<Func2Error>>() {
                 eprintln!("Func2Error: {}", f2err);
             }
 

examples/tutorial9.rs

@@ -1,14 +1,14 @@
-use chainerror::prelude::v1::*;
+use chainerror::{Context as _, ErrorDown};
+
 use std::error::Error;
 use std::io;
-use std::result::Result;
 
 fn do_some_io() -> Result<(), Box<dyn Error + Send + Sync>> {
     Err(io::Error::from(io::ErrorKind::NotFound))?;
     Ok(())
 }
 
-derive_str_context!(Func2Error);
+chainerror::str_context!(Func2Error);
 
 fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     let filename = "foo.txt";
@@ -16,11 +16,11 @@ fn func2() -> Result<(), Box<dyn Error + Send + Sync>> {
     Ok(())
 }
 
-derive_str_context!(Func1ErrorFunc2);
-derive_str_context!(Func1ErrorIO);
+chainerror::str_context!(Func1ErrorFunc2);
+chainerror::str_context!(Func1ErrorIO);
 
 fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
-    func2().context(Func1ErrorFunc2("func1 error calling func2".to_string()))?;
+    func2().context(Func1ErrorFunc2::new("func1 error calling func2"))?;
     let filename = "bar.txt";
     do_some_io().context(Func1ErrorIO(format!("Error reading '{}'", filename)))?;
     Ok(())
@@ -28,7 +28,7 @@ fn func1() -> Result<(), Box<dyn Error + Send + Sync>> {
 
 fn main() -> Result<(), Box<dyn Error + Send + Sync>> {
     if let Err(e) = func1() {
-        if let Some(s) = e.downcast_ref::<ChainError<Func1ErrorIO>>() {
+        if let Some(s) = e.downcast_ref::<chainerror::Error<Func1ErrorIO>>() {
             eprintln!("Func1ErrorIO:\n{:?}", s);
         }
 

tests/test_basic.rs

@@ -0,0 +1,33 @@
+use chainerror::Context;
+
+#[test]
+fn test_basic() {
+    use std::path::PathBuf;
+    type BoxedError = Box<dyn std::error::Error + Send + Sync>;
+    fn read_config_file(path: PathBuf) -> Result<(), BoxedError> {
+        // do stuff, return other errors
+        let _buf = std::fs::read_to_string(&path).context(format!("Reading file: {:?}", &path))?;
+        // do stuff, return other errors
+        Ok(())
+    }
+    fn process_config_file() -> Result<(), BoxedError> {
+        // do stuff, return other errors
+        read_config_file("_non_existent.txt".into()).context("read the config file")?;
+        // do stuff, return other errors
+        Ok(())
+    }
+
+    if let Err(e) = process_config_file() {
+        let os_notfound_error = std::io::Error::from_raw_os_error(2);
+        let s = format!("{:?}", e);
+        let lines = s.lines().collect::<Vec<_>>();
+        assert_eq!(lines.len(), 5);
+        assert!(lines[0].starts_with("tests/test_basic.rs:"));
+        assert_eq!(lines[1], "Caused by:");
+        assert!(lines[2].starts_with("tests/test_basic.rs:"));
+        assert_eq!(lines[3], "Caused by:");
+        assert_eq!(lines[4], format!("{:?}", os_notfound_error));
+    } else {
+        panic!();
+    }
+}

tests/test_iter.rs

@@ -1,8 +1,7 @@
-use chainerror::prelude::v1::*;
+use chainerror::Context;
 use std::error::Error;
 use std::io;
 
-#[cfg(not(feature = "display-cause"))]
 #[test]
 fn test_iter() -> Result<(), Box<dyn Error + Send + Sync>> {
     use std::fmt::Write;
@@ -32,9 +31,8 @@ fn test_iter() -> Result<(), Box<dyn Error + Send + Sync>> {
     Ok(())
 }
 
-#[cfg(feature = "display-cause")]
 #[test]
-fn test_iter() -> Result<(), Box<dyn Error + Send + Sync>> {
+fn test_iter_alternate() -> Result<(), Box<dyn Error + Send + Sync>> {
     let err: Result<(), _> = Err(io::Error::from(io::ErrorKind::NotFound));
     let err = err.context("1");
     let err = err.context("2");
@@ -44,9 +42,9 @@ fn test_iter() -> Result<(), Box<dyn Error + Send + Sync>> {
     let err = err.context("6");
     let err = err.err().unwrap();
 
-    let res = err.to_string();
+    let res = format!("{:#}", err);
 
-    assert_eq!(res, "6\nCaused by:\n5\nCaused by:\n4\nCaused by:\n3\nCaused by:\n2\nCaused by:\n1\nCaused by:\nentity not found");
+    assert_eq!(res, format!("6\nCaused by:\n  5\nCaused by:\n  4\nCaused by:\n  3\nCaused by:\n  2\nCaused by:\n  1\nCaused by:\n  {:#}", io::Error::from(io::ErrorKind::NotFound)));
 
     let io_error: Option<&io::Error> = err
         .iter()