enum Values: string{
  NONE = "",
  Value1 = "Apple",
  Value2 = "Peach",
  Value3 = "Lemon"
}


Values lastHeldValue = Value3;


Is the "lastHeldValue" just "pointer + length" information, and it
points to "Lemon"; or is "Lemon" copied to another place in memory?

I am doing comparison as "if( lastHeldValue == Value3 )" and am not
sure what comparison operation it is doing in the background.

On Saturday, 18 October 2014 at 23:51:53 UTC, tcak wrote:
> enum Values: string{
>   NONE = "",
>   Value1 = "Apple",
>   Value2 = "Peach",
>   Value3 = "Lemon"
> }
>
>
> Values lastHeldValue = Value3;
>
>
> Is the "lastHeldValue" just "pointer + length" information, and it
> points to "Lemon"; or is "Lemon" copied to another place in memory?
>
> I am doing comparison as "if( lastHeldValue == Value3 )" and am not
> sure what comparison operation it is doing in the background.

The value will be "copied and pasted" where you use a Values. However, strings are cached in D, so the following problem will print "true" for both checks.

import std.stdio;

void main()
{
    enum s = "test";
    auto v1 = s;
    auto v2 = s;

    //Check that both point to the same string in memory
    writeln(v1 is v2);

    //Check that both have the same value
    writeln(v1 == v2);
}

Because enum values are copied and pasted, it is usually a bad idea to make an enum that contains arrays or classes, as everywhere you use the enum values allocates a new array/object. With strings it's okay, as they're cached.