Merge pull request rust-cli#14 from tobark/anyhow

Cargo.toml

@@ -65,6 +65,7 @@ members = [
 structopt = "0.2.10"
 failure = "0.1.3"
 exitfailure = "0.5.1"
+anyhow = "1.0"
 indicatif = "0.10.1"
 log = "0.4.6"
 env_logger = "0.6.0"

src/in-depth/signals-channels.rs

@@ -1,5 +1,6 @@
 use std::time::Duration;
 use crossbeam_channel::{bounded, tick, Receiver, select};
+use anyhow::Result;
 
 fn ctrl_channel() -> Result<Receiver<()>, ctrlc::Error> {
     let (sender, receiver) = bounded(100);
@@ -10,7 +11,7 @@ fn ctrl_channel() -> Result<Receiver<()>, ctrlc::Error> {
     Ok(receiver)
 }
 
-fn main() -> Result<(), exitfailure::ExitFailure> {
+fn main() -> Result<()> {
     let ctrl_c_events = ctrl_channel()?;
     let ticks = tick(Duration::from_secs(1));
 

src/tutorial/errors-exit.rs

@@ -1,10 +1,9 @@
-use failure::ResultExt;
-use exitfailure::ExitFailure;
+use anyhow::{Context, Result};
 
-fn main() -> Result<(), ExitFailure> {
+fn main() -> Result<()> {
     let path = "test.txt";
     let content = std::fs::read_to_string(path)
-        .with_context(|_| format!("could not read file `{}`", path))?;
+        .with_context(|| format!("could not read file `{}`", path))?;
     println!("file content: {}", content);
     Ok(())
 }

src/tutorial/errors.md

@@ -206,32 +206,21 @@ This pattern is in fact very common.
 It has one problem, though:
 We don't store the original error,
 only its string representation.
-The often used [`failure`] library has a neat solution for that:
+The often used [`anyhow`] library has a neat solution for that:
 Similar to our `CustomError` type,
-it has a [`Context`] type
-that contains a description as well as the original error.
-The library also brings with it an extension trait ([`ResultExt`])
-that adds [`context()`] and [`with_context()`] methods to `Result`.
-
-[`failure`]: https://docs.rs/failure
-[`Context`]: https://docs.rs/failure/0.1.7/failure/struct.Context.html
-[`ResultExt`]: https://docs.rs/failure/0.1.7/failure/trait.ResultExt.html
-[`context()`]: https://docs.rs/failure/0.1.7/failure/trait.ResultExt.html#tymethod.context
-[`with_context()`]: https://docs.rs/failure/0.1.7/failure/trait.ResultExt.html#tymethod.with_context
-
-To turn these wrapped error types
-into something that humans will actually want to read,
-we can further add the [`exitfailure`] crate,
-and use its type as the return type of our `main` function.
-
-Let's first import the crates by adding
-`failure = "0.1.7"` and `exitfailure = "0.5.1"` to the `[dependencies]` section
+its [`Context`] trait can be used to add a description.
+Additionally, it also keeps the original error,
+so we get a "chain" of error messages pointing out the root cause.
+
+[`anyhow`]: https://docs.rs/anyhow
+[`Context`]: https://docs.rs/anyhow/1.0/anyhow/trait.Context.html
+
+Let's first import the `anyhow` crate by adding
+`anyhow = "1.0"` to the `[dependencies]` section
 of our `Cargo.toml` file.
 
 The full example will then look like this:
 
-[`exitfailure`]: https://docs.rs/exitfailure
-
 ```rust,ignore
 {{#include errors-exit.rs}}
 ```
@@ -240,5 +229,7 @@ This will print an error:
 
 ```text
 Error: could not read file `test.txt`
-Info: caused by No such file or directory (os error 2)
+
+Caused by:
+    No such file or directory (os error 2)
 ```

src/tutorial/testing/Cargo.toml

@@ -6,8 +6,7 @@ edition = "2018"
 
 [dependencies]
 structopt = "0.2.10"
-failure = "0.1.3"
-exitfailure = "0.5.1"
+anyhow = "1.0"
 
 [dev-dependencies]
 assert_cmd = "0.10"

src/tutorial/testing/src/main.rs

@@ -1,6 +1,5 @@
 use structopt::StructOpt;
-use failure::ResultExt;
-use exitfailure::ExitFailure;
+use anyhow::{Context, Result};
 
 /// Search for a pattern in a file and display the lines that contain it.
 #[derive(StructOpt)]
@@ -12,10 +11,10 @@ struct Cli {
     path: std::path::PathBuf,
 }
 
-fn main() -> Result<(), ExitFailure> {
+fn main() -> Result<()> {
     let args = Cli::from_args();
     let content = std::fs::read_to_string(&args.path)
-        .with_context(|_| format!("could not read file `{}`", args.path.display()))?;
+        .with_context(|| format!("could not read file `{}`", args.path.display()))?;
 
     find_matches(&content, &args.pattern, &mut std::io::stdout());