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December 22, 2017 Converting member variables to strings with using reflection from base class | ||||
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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 |
December 22, 2017 Re: Converting member variables to strings with using reflection from base class | ||||
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Posted in reply to kerdemdemir | 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 -- People walk. Computers run. |
December 22, 2017 Re: Converting member variables to strings with using reflection from base class | ||||
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Posted in reply to H. S. Teoh | 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();
}
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