init code

6.Conversion/6.2 TryFrom and TryInto/Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "try_from_and_try_into"
+version = "0.1.0"

6.Conversion/6.2 TryFrom and TryInto/Cargo.toml

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+[package]
+name = "try_from_and_try_into"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

6.Conversion/6.2 TryFrom and TryInto/src/main.rs

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+//!
+//! TryFrom\TryInto 和 From\Into 非常相似，
+//! 只不过 TryFrom\TryInto 会使用 Result 来包装可能失败的结果
+//!
+
+use std::convert::TryFrom;
+use std::convert::TryInto;
+
+#[derive(Debug, PartialEq)]
+struct EvenNumber(i32);
+
+impl TryFrom<i32> for EvenNumber {
+    // 指明错误的具体类型
+    type Error = ();
+
+    // 使用 Result 来包装结果成功还是失败
+    fn try_from(value: i32) -> Result<Self, Self::Error> {
+        if value % 2 == 0 {
+            Ok(EvenNumber(value))
+        } else {
+            Err(())
+        }
+    }
+}
+
+fn main() {
+    // TryFrom
+
+    assert_eq!(EvenNumber::try_from(8), Ok(EvenNumber(8)));
+    assert_eq!(EvenNumber::try_from(5), Err(()));
+
+    // TryInto
+
+    let result: Result<EvenNumber, ()> = 8i32.try_into();
+    assert_eq!(result, Ok(EvenNumber(8)));
+    let result: Result<EvenNumber, ()> = 5i32.try_into();
+    assert_eq!(result, Err(()));
+}