qcsrc/lib/lazy.qh

   1 #ifndef LAZY_H
   2 #define LAZY_H
   3
   4 #include "oo.qh"
   5
   6 CLASS(Lazy, Object)
   7         ATTRIB(Lazy, m_get, entity(), func_null);
   8         CONSTRUCTOR(Lazy, entity() _compute)
   9         {
  10                 this.m_get = _compute;
  11         }
  12 ENDCLASS(Lazy)
  13
  14 #define LAZY(id) __lazy_##id
  15 #define LAZY_NEW(id, compute) \
  16         entity LAZY(id)() { \
  17                 static bool done; \
  18                 static entity it; \
  19                 if (!done) { it = compute; done = true; } \
  20                 return it; \
  21         }
  22 #endif