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 +, 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, );
  S s2 = S(int.max, false, );
  s1.Log();
  s2.Log();
}

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

[H. S. Teoh via Digitalmars-d-learn]

On Fri, Dec 22, 2017 at 09:13:31PM +, 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

-- 
People walk. Computers run.

Converting member variables to strings with using reflection from base class

[kerdemdemir via Digitalmars-d-learn]

I want to make a logging function for member variables by using 
reflection.


import std.stdio;

class D : B
{
override void foo() {
a  = 4.0;
b  = 3.0;
}
double a;
double b;
}

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
}
}

void foo()
{
}
}

void main()
{
 auto b = new D;
 b.Log();
}

As I wrote in the comments I want to see member variable's name 
and its value.

What is the best way to achieve that?

Erdem