添加练习

Author: windqyoung

_posts/2025-09-19-rust-try.md

@@ -0,0 +1,84 @@
+---
+title: rust try练习
+---
+
+```rust
+#![feature(try_trait_v2)]
+#![allow(unused)]
+use std::ops::{ControlFlow, FromResidual, Try};
+
+#[derive(Debug)]
+enum MyTry {
+    TOK(Vec<String>),
+    TERR(Vec<String>),
+}
+
+impl FromResidual for MyTry {
+    /// from的目的是复原对象
+    fn from_residual(residual: <Self as Try>::Residual) -> Self {
+        println!("调用 from_residual: {residual:?}");
+        let mut residual = residual;
+        residual.push("调用 from_residual".to_string());
+        MyTry::TERR(residual)
+    }
+}
+
+impl Try for MyTry {
+    type Output = Vec<String>;
+    type Residual = Vec<String>;
+
+    /// from的目的是复原对象
+    fn from_output(output: Self::Output) -> Self {
+        println!("调用 from output: {output:?}");
+        let mut output = output;
+        output.push("调用 from_output".to_string());
+        MyTry::TOK(output)
+    }
+
+    /// 在执行到?时, 调用branch来判断是继续还是返回
+    /// 继续时, 类型为 Self::Output, 
+    /// 返回时, 类型为 Self, 
+    fn branch(self) -> ControlFlow<Self::Residual, Self::Output> {
+        match self {
+            MyTry::TOK(ok) => {
+                println!("branch ok");
+                let mut ok= ok;
+                ok.push("被分支ok修改".to_string());
+                ControlFlow::Continue(ok)
+            }
+            MyTry::TERR(err) => {
+                println!("branch err");
+                let mut err = err;
+                err.push("被分支err修改".to_string());
+
+                ControlFlow::Break(err)
+            }
+        }
+    }
+}
+
+fn try1() -> MyTry {
+    let r1 = MyTry::TOK(vec!["初始化的数据".to_string()])?;
+    println!("r1 is {:?}", r1);
+
+
+    MyTry::TOK(r1)
+}
+
+fn try2() -> MyTry {
+
+    let r2 = MyTry::TERR(vec!["初始化的数据".to_string()])?;
+    println!("r2 is {:?}", r2);
+
+    MyTry::TOK(r2)
+}
+
+fn main() {
+    let rs = try1();
+    println!("rs: {:?}", rs);
+
+    let rs2 = try2();
+    println!("rs2: {rs2:?}");
+}
+
+```