Re: Converting member variables to strings with using reflection from base class

[Mengu via Digitalmars-d-learn]

On Friday, 22 December 2017 at 22:09:05 UTC, H. S. Teoh wrote:
On Fri, Dec 22, 2017 at 09:13:31PM +0000, kerdemdemir via 
Digitalmars-d-learn wrote:
I want to make a logging function for member variables by 
using reflection.
[...]
class B
{
    void Log()
    {
        auto a = [__traits(derivedMembers, D)];
        foreach(memberName; a) {
            // Somehow write only member variables with their 
names
            // Result should be : a = 4.0, b = 3.0

Try this:

        import std.traits : FieldNameTuple;
        foreach (memberName; FieldNameTuple!B) {
                writefln("%s = %s", memberName, mixin("this." ~ memberName));
        }


T

and then turn it into a LoggerMixin with a mixin template and 
re-use it any time you want.

import std.stdio : writeln, writefln;
import std.traits : FieldNameTuple;

mixin template LoggerMixin() {
  void Log() {
    foreach (memberName; FieldNameTuple!(typeof(this))) {
      writefln("%s = %s", memberName, mixin("this." ~ 
memberName));
    }

  }
}

struct S {
  int x;
  bool y;
  double z;

  mixin LoggerMixin;
}

void main() {

  S s1 = S(int.min, true, 6666);
  S s2 = S(int.max, false, 6666);
  s1.Log();
  s2.Log();
}