官术网_书友最值得收藏!

Unsafe

Rust's code is "safe" because the compiler checks and enforces certain behavior when it comes to memory access and management. However, sometimes these rules have to be forgone, making the code unsafe. unsafe is a keyword in Rust and declares a section of code that can do most of the things the C programming language would let you do. For example, it lets the user do the following (from the Rust Book, chapter 19.1):

  • Dereference a raw pointer
  • Call an unsafe function or method
  • Access or modify a mutable static variable
  • Implement an unsafe trait

These four abilities can be used for things such as very low-level device access, language interoperability (the compiler can't know what native libraries do with their memory), and so on. In most cases, and certainly in this book, unsafe is not required. In fact, the Rustonomicon (https://doc.rust-lang.org/nomicon/what-unsafe-does.html) defines a list of issues the language is trying to prevent from happening by providing the safe part:

  • Dereferencing null, dangling, or unaligned pointers.
  • Reading uninitialized memory.
  • Breaking the pointer aliasing rules.
  • Producing invalid primitive values:
    • Dangling/null references
    • Null fn pointers
    • A bool that isn't 0 or 1
    • An undefined enum discriminant
    • A char outside the ranges [0x0, 0xD7FF] and [0xE000, 0x10FFFF]
    • A non-UTF8 string
  • Unwinding into another language.
  • Causing a data race.

The fact that these potential issues are prevented in safe Rust certainly makes the life of a developer easier, especially when designing algorithms or data structures. As a consequence, this book will always work with safe Rust.

主站蜘蛛池模板: 沁水县| 金门县| 三穗县| 房山区| 永春县| 株洲市| 抚州市| 沂源县| 安福县| 太和县| 虎林市| 石屏县| 敦煌市| 舟山市| 海宁市| 厦门市| 宁南县| 长春市| 茂名市| 墨玉县| 溧阳市| 孝感市| 平凉市| 邮箱| 邢台县| 泰顺县| 沛县| 济阳县| 泾川县| 辛集市| 南康市| 吴堡县| 新平| 罗源县| 西藏| 哈密市| 渝北区| 平潭县| 尖扎县| 慈利县| 鄂托克旗|