How to implement a copy

[Pelle Månsson]

On 03/18/2010 05:43 PM, Paul D. Anderson wrote:
> If I'm implementing a struct and want to provide for duplication, is there a standard way to implement this?
>
> Here's an example:
>
> //-------------------------------
>
> struct S {
>
>      // members of the struct -- three integer values
>      int a;
>      int b;
>      int c;
>
>      // here's a copy constructor
>      this(S s) {
>          this.a = s.a;
>          this.b = s.b;
>          this.c = s.c;
>      }
>
>      // here's the dup property
>      S dup() {
>          S s;
>          result.a = this.a;
>          result.b = this.b;
>          result.c = this.c;
>          return s;
>      }
>
>      // here's opAssign for S
>      void opAssign(S s) {
>          this.a = s.a;
>          this.b = s.b;
>          this.c = s.c;
>      }
>
>
> } // end struct S
>
> // and here's a copy function
> S copy(S s) {
>      S t;
>      t.a = s.a;
>      t.b = s.b;
>      t.c = s.c;
>      return t;
> }
>
> //-------------------------------
>
> Which of these three calls is "better" (more efficient, more intuitive, more consistent...)?
>
> S s;    // the original struct
>
> S t = s.dup;     // copied via dup
> S u = S(s);      // copied via copy constructor
> S v = s;           // copied via opAssign
> S w = copy(s);  // copied via copy function
>
> Or is this a distinction without a difference?
>
> Paul
>
>
>
>

this(this) is the copy constructor, I think.

Try using that :)