Add 《精通rust》env_logger

Author: shuliang

README.org

@@ -22,8 +22,15 @@ Examples for [[https://github.com/yewstack/yew][yew]].
 
 * 《深入浅出rust》(dive into rust)
 Based on examples from [[https://book.douban.com/subject/30312231/][《深入浅出rust》]].
+
 | code               |
 | [[file:dive-into-rust/src/lib.rs][第一部分：基础知识]] |
 | [[file:dive-into-rust/src/lib.rs][第二部分：内存安全]] |
 | [[file:dive-into-rust/src/lib.rs][第三部分：高级抽象]] |
 | [[file:dive-into-rust/src/lib.rs][第四部分：线程安全]] |
+
+* 《精通rust》(Mastering rust)
+ Examples from[[https://book.douban.com/subject/35290878/][《精通rust(第2版)》]].
+
+| chapter | code       |
+|  11.5.2 | [[file:mastering-rust/ch11_log/env_logger_demo/src/main.rs][env_logger]] |

mastering-rust/ch11_log/env_logger_demo/Cargo.lock

@@ -0,0 +1,12 @@
+[package]
+name = "env_logger_demo"
+version = "0.1.0"
+authors = ["ShuLiang <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+env_logger = "0.8.4"
+user_auth = { path = "../user_auth" }
+log = { version = "0.4.14", features = ["release_max_level_error", "max_level_trace"] }

mastering-rust/ch11_log/env_logger_demo/Cargo.toml

@@ -0,0 +1,17 @@
+//! Run the demo with `RUST_LOG=user_auth=info, env_logger_demo=info cargo run`
+//! and `RUST_LOG=user_auth=info, env_logger_demo=info cargo run --release` to
+//! see the difference of log output which is configured in `../Cargo.toml`.
+//! Set env var is another way to get the same result.
+
+use log::debug;
+
+use user_auth::User;
+
+fn main() {
+    std::env::set_var("RUST_LOG", "user_auth=info, env_logger_demo=info cargo run");
+    env_logger::init();
+    debug!("env logger demo started");
+    let user = User::new("bob", "super_sekret");
+    user.sign_in("super_secret");
+    user.sign_in("super_sekret");
+}

mastering-rust/ch11_log/env_logger_demo/src/main.rs

@@ -0,0 +1,10 @@
+[package]
+name = "user_auth"
+version = "0.1.0"
+authors = ["ShuLiang <[email protected]>"]
+edition = "2018"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+log = "0.4.14"

mastering-rust/ch11_log/user_auth/Cargo.lock

@@ -0,0 +1,23 @@
+use log::{error, info};
+
+pub struct User {
+    name: String,
+    pass: String,
+}
+
+impl User {
+    pub fn new(name: &str, pass: &str) -> Self {
+        User {
+            name: name.to_string(),
+            pass: pass.to_string(),
+        }
+    }
+
+    pub fn sign_in(&self, pass: &str) {
+        if pass != self.pass {
+            info!("Signing in user: {}", self.name);
+        } else {
+            error!("Login failed for user: {}", self.name);
+        }
+    }
+}