rust/rust-error.md

@@ -101,6 +101,27 @@ pub enum MyError {
 }
 ```
 
+### thiserrorでよくあるクレートのエラー型の自動変換用の定義例
+``` rust
+pub type Result<T, E = Error> = std::result::Result<T, E>;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error(transparent)]
+    IO(#[from] std::io::Error),
+    #[error(transparent)]
+    Anyhow(#[from] anyhow::Error),
+    #[error(transparent)]
+    SerdeYaml(#[from] serde_yaml::Error),
+    #[error(transparent)]
+    SerdeJson(#[from] serde_json::Error),
+    #[error(transparent)]
+    Image(#[from] image::ImageError),
+    #[error(transparent)]
+    CSV(#[from] csv::Error),
+}
+```
+
 ### `anyhow::Error`から`thiserror`への移行方法
 方針
 * `anyhow::Result`や`Box<dyn std::error::Error>`を`pub type Result<T, E = MyError> = std::result::Result<T, E>;`へ置き換える