>文章来源于：https://reading.developerlearning.cn/reading/3-2018-04-18-strings-part1/
*Go 标准包阅读*
Go 版本：go 1.10.1
### strings
- builder.go
- builder_test.go
- compare.go
- compare_test.go
- example_test.go
- export_test.go
- reader_test.go
- reader.go
### 问题清单
以下是我们在阅读过程中的一些问题，希望可以引起大家的关注，也欢迎大家提出自己的理解，最好可以给以文章总结。
1. defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(1))
2. runtime.ReadMemStats(&m1)
3. defer_lock.go
```go
package main
import (
"sync"
)
func main() {
var mu sync.Locker = new(I)
defer LockUnlock(mu)()
println("doing")
}
func LockUnlock(mu sync.Locker) (unlock func()) {
mu.Lock()
return mu.Unlock
}
type I struct{}
func (i *I) Lock() {
println("lock")
}
func (i *I) Unlock() {
println("unlock")
}
```
4. buf := make([]byte, len(b.buf), 2*cap(b.buf)+n) 为什么是2倍呢？
5. // NOTE(rsc): This function does NOT call the runtime cmpstring function,
// because we do not want to provide any performance justification for
// using strings.Compare. Basically no one should use strings.Compare.
// As the comment above says, it is here only for symmetry with package bytes.
// If performance is important, the compiler should be changed to recognize
// the pattern so that all code doing three-way comparisons, not just code
// using strings.Compare, can benefit.
6. b.buf = append(b.buf, s...) s是string，b.buf是[]byte
7. int int64的问题？ 在32位机器上进行int64原子操作时的panic
8. defer LockUnlock(mu),如果LockUnlock(mu)没有带()，则会丢失func函数的执行
9. if r < utf8.RuneSelf
10. if cap(b.buf)-l < utf8.UTFMax {
11. Example
12. xxx_test.go 其实是xxx包，但是又不想放到xxx包里面，因为它只是提供给_test.go包使用的函数。
13. rune 码点的处理（reader.go prevRune int // index of previous rune; or < 0）
14. off 与 offset 尴尬的问题
15. whence where when ？[wiki-whence](https://en.wiktionary.org/wiki/whence)
16. // It is similar to bytes.NewBufferString but more efficient and read-only.
17. Go 1.10 开始引入了 builder
[go1.10.builder](https://golang.org/doc/go1.10#strings)
```
# https://golang.org/doc/go1.10#strings
strings ¶
A new type Builder is a replacement for bytes.Buffer for the use case of accumulating text into a string result. The Builder's API is a restricted subset of bytes.Buffer's that allows it to safely avoid making a duplicate copy of the data during the String method.
```
## 延伸阅读
1. [wiki-whence](https://en.wiktionary.org/wiki/whence)
2. [Go 延迟函数 defer 详解](https://mp.weixin.qq.com/s/5xeAOYi3OoxCEPe-S2RE2Q)
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