feedc0de/boost_smart_ptr
1
0
Fork 0
forked from boostorg/smart_ptr
Code Pull Requests Activity

Added support for calling enable_shared_from_this::shared_from_this in

Browse Source 
constructors.  Closes #1696.



[SVN r43738]
This commit is contained in:
Frank Mori Hess
2008-03-20 19:32:43 +00:00
parent 2eb3991630
commit 1c2d780f9e
4 changed files with 252 additions and 27 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/boost/enable_shared_from_this.hpp
+41 -10
View File
@@ -23,9 +23,32 @@ namespace boost
template<class T> class enable_shared_from_this
{
// dynamic cast to template type doesn't work in constructor, so we have
// to use lazy initialization
void init_internal_shared_once() const
{
if(owned() == false && _internal_shared_this == 0)
{
_internal_shared_this = shared_ptr<T>(dynamic_cast<T *>(const_cast<enable_shared_from_this*>(this)),
detail::sp_deleter_wrapper(), detail::ignore_enable_shared_from_this_tag());
BOOST_ASSERT(_internal_shared_this.get() == this);
_internal_weak_this = _internal_shared_this;
}
}
bool owned() const
{
return _owned;
}
typedef T _internal_element_type; // for bcc 5.5.1
mutable shared_ptr<_internal_element_type> _internal_shared_this;
mutable weak_ptr<_internal_element_type> _internal_weak_this;
mutable bool _owned;
protected:
enable_shared_from_this()
enable_shared_from_this():
_owned(false)
{
}
@@ -38,14 +61,20 @@ protected:
return *this;
}
~enable_shared_from_this()
// virtual destructor because we need a vtable for dynamic_cast from base to derived to work
virtual ~enable_shared_from_this()
{
// make sure no dangling shared_ptr objects were created by the
// user calling shared_from_this() but never passing ownership of the object
// to a shared_ptr.
BOOST_ASSERT(owned() || _internal_shared_this.use_count() <= 1);
}
public:
shared_ptr<T> shared_from_this()
{
init_internal_shared_once();
shared_ptr<T> p(_internal_weak_this);
BOOST_ASSERT(p.get() == this);
return p;
@@ -53,19 +82,21 @@ public:
shared_ptr<T const> shared_from_this() const
{
init_internal_shared_once();
shared_ptr<T const> p(_internal_weak_this);
BOOST_ASSERT(p.get() == this);
return p;
}
// Note: No, you don't need to initialize _internal_weak_this
//
// Please read the documentation, not the code
//
// http://www.boost.org/libs/smart_ptr/enable_shared_from_this.html
typedef T _internal_element_type; // for bcc 5.5.1
mutable weak_ptr<_internal_element_type> _internal_weak_this;
template<typename U>
void _internal_accept_owner(shared_ptr<U> &owner) const
{
init_internal_shared_once();
get_deleter<detail::sp_deleter_wrapper>(_internal_shared_this)->set_deleter(owner);
owner = _internal_shared_this;
_internal_shared_this.reset();
_owned = true;
}
};
} // namespace boost