that take a user-suppiled lambda to generate the data needed to render our desired compile-time resource! These are e�ectively templated functions, but we will use the cleaner auto parameter syntax for

Orthogonality In Design cppcon 2021 Symmetry In C++ Code • C++’s most common symmetry example: Resource Management ... { Bar b; //...do stuff with b } Enter the block, object is created Leave the object is destroyed Stack-based (automatic) data objects • Is symmetry to define state based on control-flow (static lexical scoping) • Edge cases managed by the C++ Standard (Guaranteed!) “The compiler Orthogonality In Design cppcon 2021 Symmetry In C++ Code • C++’s most common symmetry example: Resource Management ... { Bar b; //...do stuff with b } Enter the block, object is created Leave the

Exceptions were designed for ? • Program has encountered a serious error, and getting out of this control flow to prevent data corruption or other damage is more important than trying to continue onward code ? 26 Bloomberg Exceptional DefinitionSituation : Need to explicitly give back / release a resource acquired during an operation before leaving the function / exception block. Exceptions can leave block catches the exception, releases a resource and usually rethrows the exception 27 Bloomberg Exceptional Resource Management30 Bloomberg Exceptional Resource Management int process_file(const std::string&

jjhou@ccca.nctu.edu.tw FAX 886-3-5733976 7 第一版序 有一种软件名曰version control，用来记录程序开发过程中的各种版本，以应不时之需，可以 随时反省、检查、回复过去努力的轨迹。 遗憾的是人的大脑没有version control 的能力。学习过程的彷徨犹豫、挫折困顿、在日积月 累的渐悟或x那之间的顿悟之后，彷佛都成了遥远模糊的回忆；而屡起屡仆、大惑不解的地 再跌倒的地方做上 记号，永志不忘？谁会把推敲再三的心得殷实详尽地记录下来，为后学铺一条红地毯？也许， 没有version control 正是人类的本能，空出更多的脑力心力与精力，追求更新的事物。 但是，作为信息教育体系一员的我，不能不有version control。事实上我亦从来没有忘记初学 MFC 的痛苦：C++ 语言本身的技术问题是其一，MFC 庞大类别库的命名规则是其二，熟知 的Windows 397 Callback 函式 / 398 目 錄 19 * 閒置時間（idle time）的處理：OnIdle / 403 Dialog 與 Control / 406 通用對話盒（Common Controls） / 407 本章回顧 / 409 第７章 簡單而完整：MFC 骨幹程式 / 411

dangling pointers" - WikipediaMemory Safety - Invalidation Invalidation occurs when an object or resource is modified or deallocated, causing references, pointers, or iterators that were pointing to it vec[index] = 0; // valid vec.clear(); vec[index] = 2; // invalid }Goals – Control Flow Validate based of control flow for: if/else, for loops, etc... void foo() { my_vector vec = { /* {1,1} });Control Flow Record and validate control flow enum class control_flow { if_, else_if, for_, return_, /*...*/ }; if (cond) { M::add<control_flow::if_>; } M::add<control_flow::end_scope>;Macro

who these people are??Good Concurrency = Good Conversation (3/3) Each person is competing for a resource I don’t know who these people are??Does our hardware support Concurrency? Brief Architecture ● One mechanism for achieving concurrency is a ‘thread’ ○ A ‘thread’ allows us to execute two control flows at the same time ○ The ‘main thread’ is where our program starts ■ We may then have 1 or data, and kernel context ○ A thread has its own thread id (TID) ○ A thread has its own logical control flow ○ A thread has its own stack for local variables 40 Figure from: Computer Systems a Programmer's

decltype(auto) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2.4 Control flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Chapter 02: Language Usability Enhancements When we declare, define a variable or constant, and control the flow of code, object-oriented functions, template programming, etc., before the runtime, it 2.4 Control flow CHAPTER 02: LANGUAGE USABILITY ENHANCEMENTS decltype(auto) look_up_a_string_1() { return lookup1(); } decltype(auto) look_up_a_string_2() { return lookup2(); } 2.4 Control flow

automatically manage the lifetime of its resource. ▪ Smart Pointers ▪ Allocate und deallocate their resource in the constructor and destructor according to the RAII idiom (Resource Acquisition Is Initialization) ▪ Release the resource if the smart pointer goes out of scope ▪ Are available in four versions raii.cppOverview Name C++ Standard Description std::auto_ptr C++98 ▪ Owns the resource exclusively ▪ „Moves“ its resource during a copy operation std::unique_ptr C++11 ▪ Owns the resource exclusively ▪ Can not be copied ▪ Deals with non-copy objects std::shared_ptr C++11 ▪ Shares a resource ▪ Supports

~B() { use_resource_XYZ(); } }; make_resource_XYZ(); { Container container; container.insert(b); container.erase(b); } // Obj containing 'b' may be not deleted yet. destroy_resource_XYZ(); Need ~B() { use_resource_XYZ(); } }; make_resource_XYZ(); { Container container; container.insert(b); container.erase(b); } // Obj containing 'b' must be already deleted. destroy_resource_XYZ(); Synchronous parallel performance. ● ● Execution policies: Parallel range algorithms accept execution policies to control parallelism. ● Random access ranges: Algorithms require random-access ranges for efficient parallelization