scoped pointer and BCB5

From: John Maddock (John_Maddock_at_[hidden])
Date: 2001-12-28 07:51:01

At the risk of muddying the waters still further, I have a version of
scoped_ptr which:

* doesn't change the implementation at all for existing compilers
* fixes the premature destructor instantiation problem with bcb5, without
increasing the size of the object (by using a static callback pointer). 
Really this is just a modified version of Fernando's grinning_pointer.

On the down side:

* for non-Borland users this introduces a gatuitous dependency change in
smart_ptr.
* introduces a subtle difference in behaviour between Borland and
non-Borland compilers.

Anyway here is the code:

template<typename T> class scoped_ptr : noncopyable {

  T* ptr;
  #ifdef __BORLANDC__
  static void (*s_callback)(T*);
  #endif

 public:
  typedef T element_type;

  explicit scoped_ptr( T* p=0 ) : ptr(p) 
  {
#ifdef __BORLANDC__
    if(0 == s_callback) s_callback = &checked_delete<T>;
#endif
  }  // never throws
  ~scoped_ptr()                 
  { 
#ifndef __BORLANDC__
    checked_delete(ptr);
#else
    //assert(s_callback);
    s_callback(ptr);
#endif 
  }
  void reset( T* p=0 )          { if ( ptr != p ) { checked_delete(ptr);
ptr = p; } }
  T& operator*() const          { return *ptr; }  // never throws
  T* operator->() const         { return ptr; }  // never throws
  T* get() const                { return ptr; }  // never throws
#ifdef BOOST_SMART_PTR_CONVERSION
  // get() is safer! Define BOOST_SMART_PTR_CONVERSION at your own risk!
  operator T*() const           { return ptr; }  // never throws 
#endif
  };  // scoped_ptr
  
#ifdef __BORLANDC__
template <class T>
void (*scoped_ptr<T>::s_callback)(T*);
#endif

BTW the btl tests all compile OK with this version of scoped_ptr (excluding
unit_test_suite_ex_test.cpp whcih still seems to have problems with bind
usage).

- John Maddock
http://ourworld.compuserve.com/homepages/john_maddock/