增加对drop(_x)函数的解释 #1254
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增加对drop(_x)函数的解释 #1254
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sunface
reviewed
Aug 21, 2023
| @@ -158,6 +158,8 @@ Bingo，完美拿走了所有权，而且这种实现保证了后续的使用必 | |||
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| 细心的同学可能已经注意到，这里直接调用了 `drop` 函数，并没有引入任何模块信息，原因是该函数在[`std::prelude`](https://course.rs/appendix/prelude.html)里。 | |||
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| > 事实上，能被显式调用的drop(_x)函数只是个空函数，在拿走目标值的所有权后没有任何操作。而由于其持有目标值的所有权，在drop(_x)函数结束之际，编译器会执行_x真正的析构函数，从而完成释放资源的操作。换句话说，drop(_x)函数只是帮助目标值的所有者提前离开了作用域。 | |||
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这是官方文档对此的说明
https://doc.rust-lang.org/std/mem/fn.drop.html
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这里对显式调用的drop(_x)函数未做解释，让人稍有困惑。我增加了一段注解，以让读者更好地理解drop(_x)的机理。