wanghenshui · wanghenshui · Sep 8, 2022 · Sep 2, 2022 · Sep 7, 2022 · Sep 7, 2022
diff --git a/README.md b/README.md
@@ -32,7 +32,7 @@ RSS使用仓库的release RSS [链接](https://github.com/wanghenshui/cppweeklyn
 | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- | --------------------- |
 | [五十一](./posts/051.md) | [五十二](./posts/052.md) | [五十三](./posts/053.md) | [五十四](./posts/054.md) | [五十五](./posts/055.md) | [五十六](./posts/056.md) | [五十七](./posts/057.md) | [五十八](./posts/058.md) | [五十九](./posts/059.md) | [六十期](./posts/060.md) |
 | [六十一](./posts/061.md) | [六十二](./posts/062.md) | [六十三](./posts/063.md) | [六十四](./posts/064.md) | [六十五](./posts/065.md) | [六十六](./posts/066.md) | [六十七](./posts/067.md) | [六十八](./posts/068.md) | [六十九](./posts/069.md) | [七十期](./posts/070.md) |
-| [七十一](./posts/071.md) |[七十二](./posts/072.md)|[七十三](./posts/073.md)|[七十四](./posts/074.md)|[七十五](./posts/075.md)|[七十六](./posts/076.md)|[七十七](./posts/077.md)|[七十八](./posts/078.md)|||
+| [七十一](./posts/071.md) |[七十二](./posts/072.md)|[七十三](./posts/073.md)|[七十四](./posts/074.md)|[七十五](./posts/075.md)|[七十六](./posts/076.md)|[七十七](./posts/077.md)|[七十八](./posts/078.md)|[七十九](./posts/079.md)||
 
 
 ---
diff --git a/posts/078.md b/posts/078.md
@@ -4,10 +4,8 @@ title:  第78期
 ---
 # C++ 中文周刊 第78期
 
-
 从[reddit](https://www.reddit.com/r/cpp/)/[hackernews](https://news.ycombinator.com/)/[lobsters](https://lobste.rs/)/[meetingcpp](https://www.meetingcpp.com/blog/blogroll/items/Meeting-Cpp-weekly-Blogroll-344.html)摘抄一些c++动态
 
-
 [周刊项目地址](https://github.com/wanghenshui/cppweeklynews)｜[在线地址](https://wanghenshui.github.io/cppweeklynews/) ｜[知乎专栏](https://www.zhihu.com/column/jieyaren) |[腾讯云+社区](https://cloud.tencent.com/developer/column/92884)
 
 弄了个qq频道，[手机qq点击进入](https://qun.qq.com/qqweb/qunpro/share?_wv=3&_wwv=128&inviteCode=xzjHQ&from=246610&biz=ka)
@@ -16,7 +14,7 @@ title:  第78期
 
 可以贴在下一期草稿里 [草稿链接](https://github.com/wanghenshui/cppweeklynews/pull/9)
 
-2020 09 02
+2022 09 02
 
 ---
 
@@ -26,14 +24,14 @@ title:  第78期
 
 [编译器信息最新动态推荐关注hellogcc公众号 本周更新 2022-08-31 第165期](https://github.com/hellogcc/osdt-weekly/blob/master/weekly-2022/2022-08-31.md)
 
-
 ## 文章
 
 - [What is the “vector pessimization”?](https://quuxplusone.github.io/blog/2022/08/26/vector-pessimization/)
 
 尽量让move 构造函数 noexcept， 不然用vector可能有问题，多copy
 
 比如这个
+
 ```cpp
 struct Instrument {
     int n_;
@@ -63,6 +61,11 @@ vector本身的搬迁move的多余动作，如果能nothrow，move就更简单
 
 free没有size看上去是个巧妙的设计，实际上隐含了挺多脏活
 
+
+实际上，malloc/free/realloc等等，这些api还是太低层太精细了。对于使用者心理负担很大。
+
+感谢@lh_mouse补充
+
 - [C++ Coroutines: Understanding the Compiler Transform](https://lewissbaker.github.io/2022/08/27/understanding-the-compiler-transform)
 
 协程背后都做了啥
@@ -88,13 +91,15 @@ int main(int, char** argv){
     fn2();     // ignoring return value with [[nodiscard]]
 }
 ```
+
 - [Do we need the Y-combinator in C++? ](http://ib-krajewski.blogspot.com/2017/10/do-we-need-y-combinator-in-c-and.html?m=1)
 
 老文，科普一下概念。
 
 - [constexpr Function Parameters](https://www.elbeno.com/blog/?p=1685)
 
 参数不是constexpr
+
 ```cpp
 consteval auto square(int x) -> int { return x * x; }
 
@@ -105,7 +110,6 @@ constexpr auto twice_square(int x) -> int { return square(x); }
 
 - [实现一个trivially_copyable的tuple ](http://www.purecpp.cn/detail?id=2309)
 - [并发与异步执行流中的对象角色概述(一) ](http://www.purecpp.cn/detail?id=2310)
-
 - [编程语言-从来如此的便是对吗？](https://zhuanlan.zhihu.com/p/558778083)
 
 看个乐
@@ -123,6 +127,7 @@ constexpr auto twice_square(int x) -> int { return square(x); }
 - [Why am I getting a null pointer crash when trying to call a method on my C++/WinRT object?](https://devblogs.microsoft.com/oldnewthing/20220901-00/?p=107097)
 
 为什么大哥解bug这么熟练
+
 ## 视频
 
 - [C++ Weekly - Ep 339 - `static constexpr` vs `inline constexpr`](https://www.youtube.com/watch?v=QVHwOOrSh3w)
@@ -131,6 +136,9 @@ static constexpr 和 inline constexpr区别。inline constexpr能合并文件重
 
 聪明的你想到了static inline constexpr。这个效果就是static constexpr。static限制了范围
 
+当然，-fmerge-contants能从另一个层面解决这个问题
+
+感谢@lh_mouse补充
 
 ## 开源项目需要人手
 

diff --git a/posts/079.md b/posts/079.md
@@ -0,0 +1,248 @@
+---
+layout: post
+title:  第79期
+---
+# C++ 中文周刊 第79期
+
+
+从[reddit](https://www.reddit.com/r/cpp/)/[hackernews](https://news.ycombinator.com/)/[lobsters](https://lobste.rs/)/[purecpp](http://www.purecpp.cn/)知乎等等摘抄一些c++动态
+
+
+[周刊项目地址](https://github.com/wanghenshui/cppweeklynews)｜[在线地址](https://wanghenshui.github.io/cppweeklynews/) ｜[知乎专栏](https://www.zhihu.com/column/jieyaren) |[腾讯云+社区](https://cloud.tencent.com/developer/column/92884)
+
+弄了个qq频道，[手机qq点击进入](https://qun.qq.com/qqweb/qunpro/share?_wv=3&_wwv=128&inviteCode=xzjHQ&from=246610&biz=ka)
+
+欢迎投稿，推荐或自荐文章/软件/资源等
+
+
+可以贴在下一期草稿里 [草稿链接](https://github.com/wanghenshui/cppweeklynews/pull/10.md)
+
+2022 0908 提前发了。周五有事
+---
+
+## 资讯
+
+标准委员会动态/ide/编译器信息放在这里
+
+llvm 15发布了。c++20支持等等一大堆修改
+
+[lld 15 ELF changes ](https://maskray.me/blog/2022-09-05-lld-15-elf-changes)
+
+[编译器信息最新动态推荐关注hellogcc公众号 本周更新  2022-09-07 第166期](https://github.com/hellogcc/osdt-weekly/blob/master/weekly-2022/2022-09-07.md)
+
+
+## 文章
+
+- [使用协程需要注意的问题（一） ](http://www.purecpp.cn/detail?id=2313)
+
+要注意协程被线程切换影响
+
+- [C++23特性总结 - 上](https://zhuanlan.zhihu.com/p/562383157)
+- [C++23特性总结 - 下](https://zhuanlan.zhihu.com/p/562383556)
+
+c++23详细总结
+
+- [使用 C++ 20 协程封装 RDMA 操作](https://zhuanlan.zhihu.com/p/553140760)
+- [使用 C++ 20 协程封装 UCX](https://zhuanlan.zhihu.com/p/555971343)
+
+c++20应用协程举例
+
+- [STL源码分析之std::function](https://zhuanlan.zhihu.com/p/560964284)
+- [g++8.3，sizeof(std::function)为什么等于32](https://www.zhihu.com/question/530797704/answer/2658642917)
+
+std::function的分析
+
+- [用户态操作系统之四 Seastar的init函数与stop](https://zhuanlan.zhihu.com/p/561202708)
+- [用户态操作系统之五 Seastar的timer](https://zhuanlan.zhihu.com/p/561214124)
+- [用户态操作系统之六 Seastar的跨线程通信](https://zhuanlan.zhihu.com/p/561511141)
+
+seastar的一些代码走读。可以看看
+
+- [C++-模板-萃取的实现(三)](https://www.zhihu.com/column/c_1523802493980569601)
+
+其实就是编译期检测接口的能力
+
+- [C++ 20 协程 Coroutine（1，基础）](https://zhuanlan.zhihu.com/p/561623494)
+- [C++ 20 协程 Coroutine（2，等待体）](https://zhuanlan.zhihu.com/p/561864514)
+- [C++ 20 协程 Coroutine（3，剖析）](https://zhuanlan.zhihu.com/p/561884301)
+
+一组协程教程
+
+- [Did you know that with C++20 (constexpr containers) TMP can be achieved with STL ](https://github.com/QuantlabFinancial/cpp_tip_of_the_week/)
+
+```cpp
+#include <ranges>
+
+template <auto Begin, auto End, auto List>
+auto slice = List
+           | std::ranges::views::drop(Begin)
+           | std::ranges::views::take(End);
+
+static_assert(
+  slice<1_c, 2_c, boost::mp::list<int, double, float>()>
+  ==
+                  boost::mp::list<double, float>());
+```
+
+typelist实现更简单了。恐怖
+
+- [A moved from optional](https://akrzemi1.wordpress.com/2022/09/06/a-moved-from-optional/)
+
+optinal的move并不会真正的move T, 让T为无效value
+
+```cpp
+template <typename T>
+void test(T v)
+{
+  optional<T> o = v;
+  assert (o);     // o contains a value
+  optional<T> p = std::move(o);
+  assert (o);     // o still contains a value!
+}
+```
+完全取决于T的move，optional会保留T的壳子。
+
+比如unique_ptr
+
+```cpp
+int * p = new int(1);
+
+optional<unique_ptr<int>> op = unique_ptr<int>(p);
+assert (op);
+assert (op->get() == p);
+
+optional<unique_ptr<int>> o2 = std::move(op);
+assert (op);                   // still contains a value
+assert (op->get() == nullptr); // the value is moved from
+assert (o2);
+assert (o2->get() == p);
+```
+
+unique_ptr内部会搬走，但本身是还在optional里的。这样实现更快，对于trival类型，这样优化的可以直接memcpy，更高效一些
+大概实现成这个样子
+
+```cpp
+template <typename Trivial>
+class optional<Trivial>
+{
+  bool     _is_initialized;
+  Trivial  _value;
+
+  optional() : _is_initialized(false) {}
+  // use defaulted copy and move 
+};
+```
+
+- [Using std::unique_ptr With C APIs](https://eklitzke.org/use-unique-ptr-with-c-apis)
+
+```cpp
+// Second argument is a pointer to the type of std::fclose, we could also have
+// written it out explicitly as std::unique_ptr<FILE, int (*)(FILE*)>.
+using FilePtr = std::unique_ptr<FILE, decltype(std::fclose) *>;
+
+// Instantiate the FILE* with the destructor we want.
+FilePtr file(std::fopen(filename, "rbe"), std::fclose);
+
+// Do stuff with the file
+std::fread(buf_.data(), 1, buf_.size(), file.get());
+```
+
+比写个deferGuard能更干净些
+
+```cpp
+using XXH3StatePtr = std::unique_ptr<XXH3_state_t, decltype(XX3_freeState) *>;
+XXH3StatePtr state(XXH3_createState(), XXh3_freeState);
+```
+但这种写法的问题在于，需要判定创建失败/指针是否有效
+
+
+- [C++23’s new function syntax](https://www.elbeno.com/blog/?p=1696)
+
+一个简单的函数
+
+```cpp
+[[nodiscard]] auto say_a_to(
+    std::string_view what, std::string_view name) -> std::string {
+  return std::string{what} + ", " + std::string{name} + "!";
+}
+
+say_a_to("Hi", "Kate"); // -> "Hi, Kate!"
+
+struct {
+  [[nodiscard]] auto operator()(
+      std::string_view what, std::string_view name) const -> std::string {
+    return std::string{what} + ", " + std::string{name} + "!";
+  }
+} say_b_to;
+
+say_b_to("Hello", "Tony"); // -> "Hello, Tony!"
+```
+
+没啥新奇的，但是c++23支持多维数组了，所以说`operator[]` 也算是一种函数了
+
+比如
+```cpp
+
+
+struct {
+  [[nodiscard]] auto operator[](
+      std::string_view what, std::string_view name) const -> std::string {
+    return std::string{what} + ", " + std::string{name} + "!";
+  }
+} say_d_to;
+
+say_d_to["Goodbye", "Tony"]; // -> "Goodbye, Tony!"
+```
+
+```cpp
+struct {
+  template <std::integral ...Ts>
+  [[nodiscard]] auto operator[](Ts... ts) const noexcept {
+    return (0 + ... + ts);
+  }
+} sum;
+const auto s1 = sum[1, 2, 3]; // 6
+const auto s2 = sum[];        // 0
+```
+
+我只能说看个乐，别这么写求求了
+## 视频
+
+- [C++ Weekly - Ep 340 - Finally! A Simple String Split in C++! ](https://www.youtube.com/watch?v=V14xGZAyVKI)
+
+```cpp
+#include <iostream>
+#include <ranges>
+#include <string_view>
+
+int main() {
+
+  // this is lazily evaluated
+  auto strings = std::string_view{"Hello C++ 20"} | std::views::split(' ');
+
+  // the result is a range of ranges
+
+  for (const auto &ref : strings) {
+    // C++ 20
+    std::cout << '\n' << std::string_view{ref.begin(), ref.end()};
+    // C++ 23
+    std::cout << '\n' << std::string_view{ref};
+  }
+}
+```
+
+## 开源项目需要人手
+
+- [asteria](https://github.com/lhmouse/asteria) 一个脚本语言，可嵌入，长期找人，希望胖友们帮帮忙，也可以加群384042845和作者对线
+- [pika](https://github.com/OpenAtomFoundation/pika) 一个nosql 存储， redis over rocksdb，非常需要人贡献代码胖友们， 感兴趣的欢迎加群294254078前来对线
+
+## 工作招聘
+
+寒冬了
+
+华为出新手机了，但我不买，因为想把寒冬传给它
+---
+
+看到这里或许你有建议或者疑问或者指出错误，请留言评论! 多谢!  你的评论非常重要！也可以帮忙点赞收藏转发！多谢支持！
+
+[本文永久链接](https://wanghenshui.github.io/cppweeklynews/posts/079.html)