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Smart Pointers to boost your code

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27 Sep 2004CPOL13 min read 1.1M   2.5K   227  
A beginner's introduction to the smart pointers provided by the boost library.
#ifndef BOOST_SCOPED_ARRAY_HPP_INCLUDED
#define BOOST_SCOPED_ARRAY_HPP_INCLUDED

//  (C) Copyright Greg Colvin and Beman Dawes 1998, 1999.
//  Copyright (c) 2001, 2002 Peter Dimov
//
//  Permission to copy, use, modify, sell and distribute this software
//  is granted provided this copyright notice appears in all copies.
//  This software is provided "as is" without express or implied
//  warranty, and with no claim as to its suitability for any purpose.
//
//  http://www.boost.org/libs/smart_ptr/scoped_array.htm
//

#include <boost/assert.hpp>
#include <boost/checked_delete.hpp>
#include <boost/config.hpp>   // in case ptrdiff_t not in std

#include <boost/detail/workaround.hpp>

#include <cstddef>            // for std::ptrdiff_t

namespace boost
{

// Debug hooks

#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)

void sp_array_constructor_hook(void * p);
void sp_array_destructor_hook(void * p);

#endif

//  scoped_array extends scoped_ptr to arrays. Deletion of the array pointed to
//  is guaranteed, either on destruction of the scoped_array or via an explicit
//  reset(). Use shared_array or std::vector if your needs are more complex.

template<class T> class scoped_array // noncopyable
{
private:

    T * ptr;

    scoped_array(scoped_array const &);
    scoped_array & operator=(scoped_array const &);

    typedef scoped_array<T> this_type;

public:

    typedef T element_type;

    explicit scoped_array(T * p = 0) : ptr(p) // never throws
    {
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
        boost::sp_array_constructor_hook(ptr);
#endif
    }

    ~scoped_array() // never throws
    {
#if defined(BOOST_SP_ENABLE_DEBUG_HOOKS)
        boost::sp_array_destructor_hook(ptr);
#endif
        boost::checked_array_delete(ptr);
    }

    void reset(T * p = 0) // never throws
    {
        BOOST_ASSERT(p == 0 || p != ptr); // catch self-reset errors
        this_type(p).swap(*this);
    }

    T & operator[](std::ptrdiff_t i) const // never throws
    {
        BOOST_ASSERT(ptr != 0);
        BOOST_ASSERT(i >= 0);
        return ptr[i];
    }

    T * get() const // never throws
    {
        return ptr;
    }

    // implicit conversion to "bool"

#if defined(__SUNPRO_CC) && BOOST_WORKAROUND(__SUNPRO_CC, <= 0x530)

    operator bool () const
    {
        return ptr != 0;
    }

#elif defined(__MWERKS__) && BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
    typedef T * (this_type::*unspecified_bool_type)() const;
    
    operator unspecified_bool_type() const // never throws
    {
        return ptr == 0? 0: &this_type::get;
    }

#else 

    typedef T * this_type::*unspecified_bool_type;

    operator unspecified_bool_type() const // never throws
    {
        return ptr == 0? 0: &this_type::ptr;
    }

#endif

    bool operator! () const // never throws
    {
        return ptr == 0;
    }

    void swap(scoped_array & b) // never throws
    {
        T * tmp = b.ptr;
        b.ptr = ptr;
        ptr = tmp;
    }

};

template<class T> inline void swap(scoped_array<T> & a, scoped_array<T> & b) // never throws
{
    a.swap(b);
}

} // namespace boost

#endif  // #ifndef BOOST_SCOPED_ARRAY_HPP_INCLUDED

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Klippel
Germany Germany
Peter is tired of being called "Mr. Chen", even so certain individuals insist on it. No, he's not chinese.

Peter has seen lots of boxes you youngsters wouldn't even accept as calculators. He is proud of having visited the insides of a 16 Bit Machine.

In his spare time he ponders new ways of turning groceries into biohazards, or tries to coax South American officials to add some stamps to his passport.

Beyond these trivialities Peter works for Klippel[^], a small german company that wants to make mankind happier by selling them novel loudspeaker measurement equipment.


Where are you from?[^]



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