update at 2020-06-23 18:08:26 by ehlxr

hello2.txt

@@ -0,0 +1 @@
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src/main.rs

@@ -4,7 +4,7 @@ use std::ops::Deref;
 use std::rc::{Rc, Weak};
 use std::sync::{mpsc, Arc, Mutex};
 use std::time::Duration;
-use std::{collections::HashMap, fmt::Display, fs::File, io, io::ErrorKind, thread};
+use std::{collections::HashMap, fmt::Display, fs, fs::File, io, io::ErrorKind, thread};
 
 fn main() {
     let mut s = String::from("Hello");
@@ -216,7 +216,7 @@ fn main() {
     };
     println!("{:?}", f.metadata());
 
-    match read_username_from_file() {
+    match read_username_from_file("hello2.txt") {
         Ok(st) => println!("{}", st),
         Err(err) => panic!("There was a problem read string: {:?}", err),
     };
@@ -1025,14 +1025,12 @@ fn main() {
         //     File::create(fnames).unwrap()
         // }
         Err(e) => match e.kind() {
-            ErrorKind::NotFound => {
+            ErrorKind::NotFound => match File::create(fnames) {
-                match File::create(fnames) {
                 Ok(f) => f,
                 Err(e) => panic!("Problem creating the file: {:?}", e),
-                }
+            },
-            }
             oe => panic!("Problem opening the file: {:?}", oe),
-        }
+        },
     };
     println!("{:?}", file);
 
@@ -1040,7 +1038,49 @@ fn main() {
     let m = Message::Quit;
     match m {
         Message::Write(s) => println!("{}", s),
+        // 此处可使用任意字符匹配其它情况
         abc => println!("{:?}", abc),
+    };
+
+    println!("----------------错误传递--------------");
+    let r = read_username_from_file("hello2.txt");
+    match r {
+        Ok(s) => println!("read from file result: {}", s),
+        Err(e) => println!("read from file error: {:?}", e),
+    };
+
+    println!("--------------泛型--------------");
+    let p = Point1 { x: 5, y: 10 };
+
+    println!("p.x = {}", p.x());
+    println!("p.y = {}", p.y());
+
+    let p1 = Point1 { x: "hello", y: 'd' };
+    let p2 = p.mixup(p1);
+    println!("{:?}", p2);
+}
+
+#[derive(Debug)]
+struct Point1<T, U> {
+    x: T,
+    y: U,
+}
+
+impl<D, Z> Point1<D, Z> {
+    fn x(&self) -> &D {
+        &self.x
+    }
+}
+
+impl Point1<i32, i32> {
+    fn y(&self) -> i32 {
+        self.y
+    }
+}
+
+impl<T, U> Point1<T, U> {
+    fn mixup<V, W>(self, p: Point1<V, W>) -> Point1<T, W> {
+        Point1 { x: self.x, y: p.y }
     }
 }
 
@@ -1278,36 +1318,36 @@ mod performance_group {
     }
 }
 
-//  传播错误
+///  传播错误
-fn read_username_from_file() -> Result<String, io::Error> {
+fn read_username_from_file(path: &str) -> Result<String, io::Error> {
     //    1.
-    let f = File::open("hello.txt");
+    // let f = File::open(path);
-
+    //
-    let mut f = match f {
+    // let mut f = match f {
-        Ok(file) => file,
+    //     Ok(file) => file,
-        Err(error) => return Err(error),
+    //     Err(error) => return Err(error),
-    };
+    // };
-
-    let mut s = String::new();
-    match f.read_to_string(&mut s) {
-        Ok(_) => Ok(s),
-        Err(e) => Err(e),
-    }
-
-    //    2.
-    //    let mut f = File::open("hello.txt")?;
     //
     // let mut s = String::new();
-    //    f.read_to_string(&mut s)?;
+    // match f.read_to_string(&mut s) {
-    //    Ok(s)
+    //     Ok(_) => Ok(s),
+    //     Err(e) => Err(e),
+    // }
+
+    //    2.
+    let mut f = File::open(path)?;
+
+    let mut s = String::new();
+    f.read_to_string(&mut s)?;
+    Ok(s)
 
     //    3.
     // let mut s = String::new();
-    //    File::open("hello.txt")?.read_to_string(&mut s)?;
+    // File::open(path)?.read_to_string(&mut s)?;
     // Ok(s)
 
     //    4.
-    //    fs::read_to_string("hello.txt")
+    // fs::read_to_string(path)
 }
 
 trait Summary {