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checked_delete.hpp

The header <boost/checked_delete.hpp> defines two function templates, checked_delete and checked_array_delete, and two class templates, checked_deleter and checked_array_deleter.

The C++ Standard allows, in 5.3.5/5, pointers to incomplete class types to be deleted with a delete-expression. When the class has a non-trivial destructor, or a class-specific operator delete, the behavior is undefined. Some compilers issue a warning when an incomplete type is deleted, but unfortunately, not all do, and programmers sometimes ignore or disable warnings.

A particularly troublesome case is when a smart pointer's destructor, such as boost::scoped_ptr<T>::~scoped_ptr, is instantiated with an incomplete type. This can often lead to silent, hard to track failures.

The supplied function and class templates can be used to prevent these problems, as they require a complete type, and cause a compilation error otherwise.

Synopsis

namespace boost
{

template<class T> void checked_delete(T * p);
template<class T> void checked_array_delete(T * p);
template<class T> struct checked_deleter;
template<class T> struct checked_array_deleter;

}

checked_delete

template<class T> void checked_delete(T * p);

Requires: T must be a complete type. The expression delete p must be well-formed.

Effects: delete p;

checked_array_delete

template<class T> void checked_array_delete(T * p);

Requires: T must be a complete type. The expression delete [] p must be well-formed.

Effects: delete [] p;

checked_deleter

template<class T> struct checked_deleter
{
    typedef void result_type;
    typedef T * argument_type;
    void operator()(T * p) const;
};

void checked_deleter<T>::operator()(T * p) const;

Requires: T must be a complete type. The expression delete p must be well-formed.

Effects: delete p;

checked_array_deleter

template<class T> struct checked_array_deleter
{
    typedef void result_type;
    typedef T * argument_type;
    void operator()(T * p) const;
};

void checked_array_deleter<T>::operator()(T * p) const;

Requires: T must be a complete type. The expression delete [] p must be well-formed.

Effects: delete [] p;

Acknowledgements

The function templates checked_delete and checked_array_delete were originally part of <boost/utility.hpp>, and the documentation acknowledged Beman Dawes, Dave Abrahams, Vladimir Prus, Rainer Deyke, John Maddock, and others as contributors.