A Perspective on C++ Standardization in 2018

Re:A Perspective on C++ Standardization in 2018 by Ace17 on Saturday December 29, 2018 @05:49AM (#18783041)

The preprocessor: Bjarne Stroustrup has been willing to get rid of it for a long time. C++20 modules are a step in this direction. However - as pointed out by John Lakos - you still need macros to build zero-cost logging facilities.

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Re:A Perspective on C++ Standardization in 2018 by frabert on Saturday December 29, 2018 @07:51AM (#18783363)

I don't think that's necessarily true, using constexpr facilities you could make a function do nothing according to a compile-time variable value

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Re:A Perspective on C++ Standardization in 2018 by Ace17 on Saturday December 29, 2018 @01:09PM (#18784852)

I agree ; however, the tricky part - I believe - is not computing the message string in case you're not going to print/record it.

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Re:A Perspective on C++ Standardization in 2018 by xamolxix on Saturday December 29, 2018 @11:00AM (#18784151)

Is IO allowed in constexpr functions?

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Re:A Perspective on C++ Standardization in 2018 by justbuchanan on Saturday December 29, 2018 @11:27AM (#18784281)

I don't think so, but for zero-cost logging you just need the conditional for your branch to be constexpr. If the branch is known not to be taken at compile time, the compiler can just throw it away.

Something like:

  void MyDebugLog(text) {
    if (<constepxr check if logging enabled>) {
      // actually log...
    }
  }

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Re:A Perspective on C++ Standardization in 2018 by Ace17 on Saturday December 29, 2018 @01:07PM (#18784840)

Corresponding citation from John Lakos about why macros could be necessary: https://www.youtube.com/watch?v=K_fTl_hIEGY&t=3140

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