1 mike  1.2 //%2006////////////////////////////////////////////////////////////////////////
  2           //
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  4           // Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
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  6           // IBM Corp.; EMC Corporation, The Open Group.
  7           // Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
  8           // IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
  9           // Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 10           // EMC Corporation; VERITAS Software Corporation; The Open Group.
 11           // Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
 12           // EMC Corporation; Symantec Corporation; The Open Group.
 13           //
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 22 mike  1.2 // ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
 23           // "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
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 30           //==============================================================================
 31           //
 32           //%/////////////////////////////////////////////////////////////////////////////
 33           
 34           #ifndef Pegasus_Magic_h
 35           #define Pegasus_Magic_h
 36           
 37           #include <Pegasus/Common/Config.h>
 38           
 39           PEGASUS_NAMESPACE_BEGIN
 40           
 41           /** The Magic class implements a convenient way to use magic numbers in

 42 kumpf 1.3     user-defined classes. Magic numbers help detect use of uninitialized,

 43 mike  1.2     destructed, or corrupted objects.
 44           

 45 kumpf 1.3     To instrument a class to use magic numbers simply add a class member

 46 mike  1.2     of type Magic<> as shown in thsi example:
 47           

 48 kumpf 1.3         \code
 49                   class MyClass
 50                   {
 51                   public:

 52 mike  1.2 

 53 kumpf 1.3             MyClass();

 54 mike  1.2 

 55 kumpf 1.3             ~MyClass();

 56 mike  1.2 

 57 kumpf 1.3             void foo();

 58 mike  1.2 

 59 kumpf 1.3         private:
 60                       Magic<0xC531B144> _magic;
 61                   };
 62                   \endcode

 63 mike  1.2 
 64               Choose whatever number you like for a magic number. The number above was

 65 kumpf 1.3     generated by the Linux uuidgen utility (Windows has a utility with the

 66 mike  1.2     same name).
 67           
 68               To test magic number, add the following expression wherever necessary
 69               (usually as the first line of every member function).
 70           

 71 kumpf 1.3         \code
 72                   PEGASUS_ASSERT_DEBUG(_magic);
 73                   \endcode

 74 mike  1.2 
 75               Here's a typical example:
 76           

 77 kumpf 1.3         \code
 78                   MyClass::~MyClass()
 79                   {
 80                       PEGASUS_ASSERT_DEBUG(_magic);
 81                   }
 82                   \endcode

 83 mike  1.2 
 84               This tests whether the magic number is 0xC531B144 and asserts if it is
 85               not.
 86           
 87               Note that using a magic number makes the user-defined class 4 bytes larger
 88               but there is no run-time overhead unless you compile with PEGASUS_DEBUG.
 89               The Magic constructor and destructor are empty without PEGASUS_DEBUG and
 90               are discarded by the compiler.
 91           
 92               CAUTION: You may be tempted to compile out the magic member when
 93               PEGASUS_DEBUG undefined. However, this will causes unpredictable
 94               behavior when debug libraries are mixed with non-debug libraries. The
 95               structure alignment and size will be different and will lead to crashes.
 96               This is only safe if a class is internal to a library.
 97           */
 98           template<Uint32 MAGIC_NUMBER>
 99           class Magic
100           {
101           public:
102           
103               /** Default constructor. Sets the magic number.
104 mike  1.2     */

105 kumpf 1.3     Magic()

106 mike  1.2     {
107           #ifdef PEGASUS_DEBUG

108 kumpf 1.3         _magic = MAGIC_NUMBER;

109 mike  1.2 #endif
110               }
111           
112               /** Destructor. Clears the magic number (with the pattern 0xDDDDDDDD).
113               */

114 kumpf 1.3     ~Magic()

115 mike  1.2     {
116           #ifdef PEGASUS_DEBUG

117 kumpf 1.3         _magic = 0xDDDDDDDD;

118 mike  1.2 #endif
119               }
120           
121               /** Allows magic number to be used as a boolean expression. This function

122 kumpf 1.3         tests the magic number and return true if valid.

123 mike  1.2     */

124 kumpf 1.3     operator bool() const
125               {

126 mike  1.2 #ifdef PEGASUS_DEBUG

127 kumpf 1.3         return _magic == MAGIC_NUMBER;

128 mike  1.2 #else

129 kumpf 1.3         return true;

130 mike  1.2 #endif
131               }
132           
133           private:
134               Uint32 _magic;
135           };
136           
137           PEGASUS_NAMESPACE_END
138           
139           #endif /* Pegasus_Magic_h */