src/tests/add-ons/print/ppd/shared/AutoDelete.h

   1 /*
   2  * Copyright 2008, Haiku.
   3  * Distributed under the terms of the MIT license.
   4  *
   5  * Authors:
   6  *              Michael Pfeiffer <laplace@users.sourceforge.net>
   7  */
   8
   9 #ifndef _AUTO_DELETE_H
  10 #define _AUTO_DELETE_H
  11
  12 #include <stdlib.h>
  13
  14 /*
  15 Typical usage of this class:
  16
  17 AClass* Klass::Method(int arg) {
  18         AutoDelete<AClass> variable(new AClass());
  19
  20         if (!IsValid(arg)) {
  21                 ...
  22                 // AutoDelete automatically deletes the AClass object.
  23                 return NULL;
  24         }
  25
  26         variable.Get()->MethodOfAClass();
  27
  28         // Use Release() to prevent deletion of AClass object.
  29         return variable.Release();
  30 }
  31 */
  32
  33 template <class Tp>
  34 class AutoDelete {
  35 private:
  36         Tp*  fObject;
  37         bool fOwnsObject;
  38
  39         // Deletes the object if it owns it
  40         void Delete()
  41         {
  42                 if (fOwnsObject) {
  43                         delete fObject; fObject = NULL;
  44                 }
  45         }
  46
  47 public:
  48
  49         // Sets the object the class owns
  50         AutoDelete(Tp* object = NULL) : fObject(object), fOwnsObject(true) { }
  51
  52         // Deletes the object if it owns it
  53         virtual ~AutoDelete()
  54         {
  55                 Delete();
  56         }
  57
  58         // Sets the object the class owns.
  59         // Deletes a previously owned object and
  60         // sets the owning flag for the new object.
  61         void Set(Tp* object)
  62         {
  63                 if (fObject == object) return;
  64
  65                 Delete();
  66                 fOwnsObject = true;
  67                 fObject = object;
  68         }
  69
  70         // Returns the object
  71         Tp* Get()
  72         {
  73                 return fObject;
  74         }
  75
  76         // Returns the object and sets owning to false
  77         // The Get method can still be used to retrieve the object.
  78         Tp* Release()
  79         {
  80                 fOwnsObject = false;
  81                 return fObject;
  82         }
  83
  84         // Sets the owning flag
  85         void SetOwnsObject(bool ownsObject)
  86         {
  87                 fOwnsObject = ownsObject;
  88         }
  89 };
  90
  91
  92 #endif