...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
The header <boost/enable_shared_from_this.hpp> defines the class template enable_shared_from_this. It is used as a base class that allows a shared_ptr to the current object to be obtained from within a member function.
enable_shared_from_this<T> defines two member functions called shared_from_this that return a shared_ptr<T> and shared_ptr<T const>, depending on constness, to this.
#include <boost/enable_shared_from_this.hpp> #include <boost/shared_ptr.hpp> #include <cassert> class Y: public boost::enable_shared_from_this<Y> { public: boost::shared_ptr<Y> f() { return shared_from_this(); } }; int main() { boost::shared_ptr<Y> p(new Y); boost::shared_ptr<Y> q = p->f(); assert(p == q); assert(!(p < q || q < p)); // p and q must share ownership }
namespace boost { template<class T> class enable_shared_from_this { public: shared_ptr<T> shared_from_this(); shared_ptr<T const> shared_from_this() const; } }
Requires: enable_shared_from_this<T> must be an accessible base class of T. *this must be a subobject of an instance t of type T . There must exist at least one shared_ptr instance p that owns t.
Returns: A shared_ptr<T> instance r that shares ownership with p.
Postconditions: r.get() == this.
Copyright © 2002, 2003 by Peter Dimov. Distributed under the Boost Software License, Version
1.0. See accompanying file LICENSE_1_0.txt or
copy at http://www.boost.org/LICENSE_1_0.txt.