WDL/destroycheck.h

   1 #ifndef _WDL_DESTROYCHECK_H_
   2 #define _WDL_DESTROYCHECK_H_
   3
   4 // this is a useful class for verifying that an object (usually "this") hasn't been destroyed:
   5 // to use it you add a WDL_DestroyState as a member of your class, then use the WDL_DestroyCheck
   6 // helper class (creating it when the pointer is known valid, and checking it later to see if it
   7 // is still valid).
   8 //
   9 // example:
  10 // class myClass {
  11 //   WDL_DestroyState dest;
  12 //   ...
  13 // };
  14 //
  15 // calling code (on myClass *classInstnace):
  16 //  WDL_DestroyCheck chk(&classInstance->dest);
  17 //  somefunction();
  18 //  if (!chk.isOK()) printf("classInstance got deleted!\n");
  19 //
  20 // NOTE: only use this when these objects will be accessed from the same thread -- it will fail miserably
  21 // in a multithreaded environment
  22
  23
  24
  25
  26 class WDL_DestroyCheck
  27 {
  28   public:
  29     class WDL_DestroyStateNextRec { public: WDL_DestroyCheck *next; };
  30
  31     WDL_DestroyStateNextRec n, *prev;
  32     WDL_DestroyCheck(WDL_DestroyStateNextRec *state)
  33     {
  34       n.next=NULL;
  35       if ((prev=state))
  36       {
  37         if ((n.next=prev->next)) n.next->prev = &n;
  38         prev->next=this;
  39       }
  40     }
  41     ~WDL_DestroyCheck()
  42     {
  43       if (prev)
  44       {
  45         prev->next = n.next;
  46         if (n.next) n.next->prev = prev;
  47       }
  48     }
  49
  50     bool isOK() { return !!prev; }
  51 };
  52
  53 class WDL_DestroyState : public WDL_DestroyCheck::WDL_DestroyStateNextRec
  54 {
  55   public:
  56     WDL_DestroyState() { next=NULL; }
  57
  58     ~WDL_DestroyState()
  59     {
  60       WDL_DestroyCheck *p = next;
  61       while (p) { WDL_DestroyCheck *np = p->n.next; p->prev=NULL; p->n.next=NULL; p=np; }
  62     }
  63 };
  64
  65 #endif