update at 2020-06-16 18:11:50 by ehlxr

.gitignore

@@ -0,0 +1,4 @@
+/target
+**/*.rs.bk
+.vscode
+.idea

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "hello_macro"
+version = "0.1.0"
+
+[[package]]
+name = "hello_macro_derive"
+version = "0.1.0"
+dependencies = [
+ "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "proc-macro2"
+version = "0.4.30"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "quote"
+version = "0.6.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "rust_study"
+version = "0.1.0"
+dependencies = [
+ "hello_macro 0.1.0",
+ "hello_macro_derive 0.1.0",
+]
+
+[[package]]
+name = "syn"
+version = "0.14.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "unicode-xid"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[metadata]
+"checksum proc-macro2 0.4.30 (registry+https://github.com/rust-lang/crates.io-index)" = "cf3d2011ab5c909338f7887f4fc896d35932e29146c12c8d01da6b22a80ba759"
+"checksum quote 0.6.13 (registry+https://github.com/rust-lang/crates.io-index)" = "6ce23b6b870e8f94f81fb0a363d65d86675884b34a09043c81e5562f11c1f8e1"
+"checksum syn 0.14.9 (registry+https://github.com/rust-lang/crates.io-index)" = "261ae9ecaa397c42b960649561949d69311f08eeaea86a65696e6e46517cf741"
+"checksum unicode-xid 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "fc72304796d0818e357ead4e000d19c9c174ab23dc11093ac919054d20a6a7fc"

Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "rust_study"
+version = "0.1.0"
+authors = ["ehlxr <ehlxr.me@gmail.com>"]
+edition = "2018"
+
+[dependencies]
+hello_macro = { path = "../hello_macro" }
+hello_macro_derive = { path = "../hello_macro/hello_macro_derive" }

hello.txt

@@ -0,0 +1 @@
+ehlxr

src/ownership_1.rs

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+fn main() {
+
+    let s = String::from("hello"); // s 进入作用域
+
+    takes_ownership(s);// s 的值移动到函数里 ...
+
+    // ... 所以到这里不再有效
+
+    let x = 5;// x 进入作用域
+
+    makes_copy(x);// x 应该移动函数里，
+// 但 i32 是 Copy 的，所以在后面可继续使用 x
+} // 这里, x 先移出了作用域，然后是 s。但因为 s 的值已被移走，所以不会有特殊操作
+
+fn takes_ownership(some_string: String) { // some_string 进入作用域
+    println!("{}", some_string);
+} // 这里，some_string 移出作用域并调用 `drop` 方法。占用的内存被释放
+
+fn makes_copy(some_integer: i32) { // some_integer 进入作用域
+    println!("{}", some_integer);
+} // 这里，some_integer 移出作用域。不会有特殊操作

src/ownership_2.rs

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+fn main() {
+    let s1 = gives_ownership(); // gives_ownership 将返回值 移给 s1
+    println!("{}", s1);
+
+    let s2 = String::from("hello"); // s2 进入作用域
+    // println!("{}", s2);
+
+    let s3 = takes_and_gives_back(s2); // s2 被移动到 takes_and_gives_back 中, 它也将返回值移给 s3
+    println!("{}", s3);
+} // 这里, s3 移出作用域并被丢弃。s2 也移出作用域，但已被移走，所以什么也不会发生。s1 移出作用域并被丢弃
+
+fn gives_ownership() -> String { // gives_ownership 将返回值移动给调用它的函数
+    let some_string = String::from("hello"); // some_string 进入作用域.
+    some_string // 返回 some_string 并移出给调用的函数
+}
+
+// takes_and_gives_back 将传入字符串并返回该值
+fn takes_and_gives_back(a_string: String) -> String { // a_string 进入作用域
+    a_string
+    // 返回 a_string 并移出给调用的函数
+}