qcsrc/lib/lazy.qh

   1 #pragma once
   2
   3 #include "oo.qh"
   4
   5 CLASS(Lazy, Object)
   6         ATTRIB(Lazy, m_get, entity());
   7         CONSTRUCTOR(Lazy, entity() _compute)
   8         {
   9                 this.m_get = _compute;
  10         }
  11 ENDCLASS(Lazy)
  12
  13 #define LAZY(id) __lazy_##id
  14 #define LAZY_NEW(id, compute) \
  15         entity LAZY(id)() { \
  16                 static bool done; \
  17                 static entity it; \
  18                 if (!done) { it = compute; done = true; } \
  19                 return it; \
  20         }