https://www.cprogramming.com/c++11/c++11-lambda-closures.html
https://www.cnblogs.com/lidabo/p/3908663.html

auto handle = [] () {
};

1. 闭包 []
   闭包的作用是对外部变量的捕捉(capture)
   [] Capture nothing (or, a scorched earth strategy?)
   [&] Capture any referenced variable by reference
   [=] Capture any referenced variable by making a copy
   [=, &foo] Capture any referenced variable by making a copy, but capture variable foo by reference
   [bar] Capture bar by making a copy; don't copy anything else
   [this] Capture the this pointer of the enclosing class
2. 参数列表 ()
3. 函数体{}

后续补充