..................................................................................... 20 Promise#catch ................................................................................................. .................................................................................... 39 then or catch? ................................................................................................ ................................................................................... 107 Promise#catch .................................................................................................

..................................................................................... 22 Promise#catch ................................................................................................. .................................................................................... 45 then or catch? ................................................................................................ .................................................................................... 131 Promise#catch ................................................................................................

..................................................................................... 21 Promise#catch ................................................................................................. .................................................................................... 41 then or catch? ................................................................................................ .................................................................................... 110 Promise#catch ................................................................................................

seen in C++ • Look at original goals/ideals of exception handling • Look at the mechanics of throw/catch • Look at Exceptions in both their use and design as seen in real code • Better thinking on the me{"Pete", 21}; apply(me); } catch (const MyStatus& s) { std::cout << "error : " << s << std::endl; } ... } } Error handling Happy Path (clean) Function signature changed } catch (...) { std::cout << Exception hygiene • Throw by value • Catch by (const) reference • Rethrow using throw with no arguments • Catch handlers with derived classes placed before catch handlers with base classes Exception

throw 5; } int main() { volatile int return_code = 0; try { return_code = start(); } catch (...) { return_code = -1; } return return_code; } 51Barrier #1 Exceptions disabled! 52☠ to convince you That was to show you that something is here. 94C++ Exceptions from throw to catch on GCC ARM 95Things that will NOT be covered here ● Nested exceptions ● Anything other than table based exceptions 96Consider the following 97 struct error {}; void foo() { try { bar(); } catch (error const& p_error) { // end up here... } } void bar() { destructible_t obj; baz();

true } }; // Load your module System.import('./myModule.js', {metadata: metadata}).catch(fun ction(ex) { console.error('Import failed', ex.stack || ex); }); 上面代码中，首先生成Traceur的全局对象 let 和 const 命令 33 // 情况一 if (true) { function f() {} } // 情况二 try { function f() {} } catch(e) { // ... } 上面两种函数声明，根据 ES5 的规定都是非法的。 但是，浏览器没有遵守这个规定，为了兼容以前的旧代码，还是支持在块级作用域 之中声明函数，因此上面两种情况实际都能运行，不会报错。 这样的规定也使得，函数参数与数组和对象的尾逗号规则，保持一致了。 catch 语句的参数 函数的扩展 165 目前，有一个提案，允许 try...catch 结构中的 catch 语句调用时不带有参 数。这个提案跟参数有关，也放在这一章介绍。 传统的写法是 catch 语句必须带有参数，用来接收 try 代码块抛出的错误。 try { // ··· } catch (error) { // ···

to throw by value, catch by const ref, and re-throw using throw.• A fail-handling mechanism void bar() { try { foo(); } catch (error_type) { // do stuff, or re-throw; } catch (…) { // do stuff, responsibility 9• A fail-handling mechanism int main() { try { bar(); } catch (error_type) { // do stuff } // don’t catch; } “Re-delegate responsibility” PART 0: WHAT ARE EXCEPTIONS 10PART I: (expensive, un-deterministic mechanism) • C++ does not return tothe throwing code (but to the catch block). Exception handlers are rare compared to function definitions. The formal usage recommendation

if (rs.next()) { System.out.println(rs.getString(1)); } } catch (SQLException ex) { Logger lgr = Logger.getLogger(Version.class.getName()); if (con != null) { con.close(); } } catch (SQLException ex) { Logger lgr = Logger.getLogger(Version.class.getName()); The getString() method retrieves the value of a specified column. The first column has index 1. } catch (SQLException ex) { Logger lgr = Logger.getLogger(Version.class.getName()); lgr.log(Level

try { g(); h(); } catch( std::exception const& ex ) { /* Handle exception */ } } Three keywords throw try catch Stack unwinding Objects on the stack are try { g(); h(); } catch( std::exception const& ex ) { /* Handle exception */ } } Three keywords throw try catch Stack unwinding Objects on the stack are try { g(); h(); } catch( std::exception const& ex ) { /* Handle exception */ } } Three keywords throw try catch Stack unwinding Objects on the stack are

ways to handle errors. One way is to use do-catch. Inside the do block, you mark code that can throw an error by writing try in front of it. Inside the catch block, the error is automatically given the printerResponse = try send(job: 1040, toPrinter: "Bi Sheng") 3 print(printerResponse) 4 } catch { 5 print(error) 6 } 7 // Prints "Job sent" E X P E R I M E N T Change the printer name send(job:toPrinter:) function throws an error. You can provide multiple catch blocks that handle specific errors. You write a pattern after catch just as you do after case in a switch. PDF conversion courtesy