[ARROW-12816] [C++] C++14 laundry list

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Component/s: C++
• External issue URL: https://github.com/apache/arrow/issues/28552
• Assignee: Unassigned
• Reporter: Ben Kietzman
• Created: 17/May/21 21:38
• Updated: 11/Jan/23 08:29
• Resolved: 29/Aug/22 12:24

Description

Improvements to make/be aware of once C++14 is available:

• Ensure that lambda closure members are moved into where ever possible/appropriate. We have a lot of local variables whose only function is getting copied into a closure, including some demotions to shared_ptr since move only types can't be closed over in c++11
• visitor pattern can be used more fluidly with template lambdas, for example we could have a utility like

  VisitInts(offset_width, offset_bytes, [&](auto* offsets) { /*mutate offsets*/ })
  

  to replace a switch statement like

  switch (offset_width) {
  case 8:
    /* mutate offsets<int8_t> */
    break;
  case 16:
    /* mutate offsets<int16_t> */
    break;
  // ...
  }
  

• deduced return type with auto:

  template <typename Container>
  auto GetBeginAndEnd(const Container& cont) {
    return std::make_pair(cont.begin(), cont.end());
  }
  

• constexpr switch, for use in type traits functions
• std::enable_if_t
• std::quoted is available for escaping strings
• std::make_unique
• standard [[deprecated]] attribute
• temporal literals such as ""s, ""ns, ...
• binary literals with place markers such as 0b1100_1111

Issue Links

• is superceded by: ARROW-17110 [C++] Move to C++17