• Ellery Newcomer (22/22) Nov 27 2012 I find myself using [abusing?] move lately:
• Dmitry Olshansky (7/30) Nov 28 2012 Yes it hacks through const/immutable at ease. The only requirement seems...

Ellery Newcomer <ellery-newcomer utulsa.edu> writes:

I find myself using [abusing?] move lately:

import std.algorithm;
import std.stdio;

struct A {
     const(int) i;
     int j;
     int k;
}

void main() {
     A* a = new A(); // pretend this is malloc or something
     // *a = A(1)
     A a2 = A(1);
     move(a2, *a);

     A[] arr = new A[](2);
     //arr[1] = *a;
     move(*a, arr[1]);
}

For the first part, I have a A* pointing to uninitialized memory and I 
need to initialize it somehow. move works I guess because it uses memcpy 
or something. Not complaining, but wondering.

The second part violates D's const semantics and maybe shouldn't be 
permitted. But it is.

Dmitry Olshansky <dmitry.olsh gmail.com> writes:

11/28/2012 7:19 AM, Ellery Newcomer пишет:
 I find myself using [abusing?] move lately:

 import std.algorithm;
 import std.stdio;

 struct A {
      const(int) i;
      int j;
      int k;
 }

 void main() {
      A* a = new A(); // pretend this is malloc or something
      // *a = A(1)
      A a2 = A(1);
      move(a2, *a);

      A[] arr = new A[](2);
      //arr[1] = *a;
      move(*a, arr[1]);
 }

 For the first part, I have a A* pointing to uninitialized memory and I
 need to initialize it somehow.

emplace should work for constructing A in a given chunk of memory.

 move works I guess because it uses memcpy
 or something. Not complaining, but wondering.

Yes it hacks through const/immutable at ease. The only requirement seems 
that it has to be shallow immutable/cont.

 The second part violates D's const semantics and maybe shouldn't be
 permitted. But it is.

I agree.

-- 
Dmitry Olshansky