compute_intensive(2); }) ); when_all then then then schedule schedule schedule13 THESE EXPRESSIONS ARE ALL SENDERS ex::sender auto work = ex::when_all( ex::schedule(sched) | ex::then([] permitting them to be treated like a black box. goto is an unstructured control flow construct conditional loop function call goto59 FIRE-AND-FORGET TASK MODELS ARE UNSTRUCTURED Fire-and-forget work

Object Parameters  if consteval  Multidimensional Subscript Operator  Attributes on Lambda-Expressions  Literal Suffix for size_t  auto(x): decay-copy in The Language  #elifdef, #elifndef, and Object Parameters  if consteval  Multidimensional Subscript Operator  Attributes on Lambda-Expressions  Literal Suffix for size_t  auto(x): decay-copy in The Language  #elifdef, #elifndef, and std::forward(self).m_name; }11 Explicit Object Parameters  Allows for recursive lambda expressions  this in a lambda accesses the object that contains the lambda, not the lambda instance itself

Coroutines  Concepts  Lambda Expression Changes  [=, this] as Lambda Capture  Templated Lambda Expressions  Pack Expansion in Lambda Captures  constexpr Changes  virtual functions  union, try/catch C++20, you need to be explicit, so: [=, this]27 Templated Lambda Expressions  Use familiar template syntax with lambda expressions [] (T x) { /* ... */ } [] (T* p) { /* . .. */ } [] (T (&a)[N]) { /* ... */ }28 Templated Lambda Expressions  Motivation 1  Generic lambda accepting a vector; you want to know T (pre C++20): [](const auto& vec) {

MacOS, iOS ）都为真 使用生成器表达式，简化成一条指令 https://cmake.org/cmake/help/latest/manual/cmake-generator-expressions.7.html#genex:PLATFORM_ID 语法： $<$< 类型 : 值 >: 为真时的表达式 > 比如 $<$:MY_NAME=”Bill 其他平台上则表现为空字符串 生成器表达式：如需多个平台可以用逗号分割 https://cmake.org/cmake/help/latest/manual/cmake-generator-expressions.7.html#genex:PLATFORM_ID 判断当前用的是哪一款 C++ 编译器 https://cmake.org/cmake/help/latest/variable/CMAKE_LANG_COMPILER_ID https://stackoverflow.com/questions/41079291/cmake-use-of-true-false-or-on-off-or-yes- no-in-generator-expressions • https://cmake.org/cmake/help/v3.7/command/if.html if 的特点：不需要加 ${} ，会自动尝试作为变量名求值 由于历史原因， if

valid and denote a type • T::rep • T::period • T::duration • T::time_point • The following expressions must be well- formed when treated as an unevaluated operand • T::is_steady • T::now() The newly-added