• Robert Fraser <fraserofthenight gmail.com> Oct 03 2007

Robert Fraser <fraserofthenight gmail.com> writes:

Gregor Richards Wrote:

 Derek Parnell wrote:
 On Wed, 03 Oct 2007 14:53:57 -0400, Bruce Adams wrote:
 
 bearophile Wrote:

 The Cray Inc is designing the Chapel Language:
 http://chapel.cs.washington.edu/
 The following notes are from the specification V. 0.750:
 http://chapel.cs.washington.edu/spec-0.750.pdf
 I think it's rather cute, it looks like a cross between C++, Fortress and
Python. Here are few things I think can be interesting for D designers too:

 - Chap. 11.5 page 65, swap operator (useful but probably not enough to justify
a new operator)


 I would like to see swap used as the default implementation of D's transfer
constructor (and C++0x's forthcoming move constructor)


 Isn't a simple template such this sufficient?
 
 template swap(TYPE)
 {
     void swap(ref TYPE a, ref TYPE b)
     {
         synchronized
         {
           TYPE temp = a;
           a = b;
           b = temp;
         }
     }
 
 }
 
 


 For the ridiculously-insane:
 
 void swap(T)(ref T a, ref T b)
 {
      synchronized {
          // this should be some kind of static for ...
          for (size_t i = 0; i < (a.sizeof/size_t.sizeof); i++) {
              (cast(size_t*) &a)[i] ^= (cast(size_t*) &b)[i];
              (cast(size_t*) &b)[i] = (cast(size_t*) &a)[i] ^ 
 (cast(size_t*) &b)[i];
              (cast(size_t*) &a)[i] ^= (cast(size_t*) &b)[i];
          }
      }
 }
 
 Add some loop unrolling and that's more efficient than memcpy :P
 
   - Gregor Richards
 
 PS: /me <3 XOR swapping


I was just going to mention that; you beat me to it!