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- // Copyright (C) 2008-2018 Lorenzo Caminiti
- // Distributed under the Boost Software License, Version 1.0 (see accompanying
- // file LICENSE_1_0.txt or a copy at http://www.boost.org/LICENSE_1_0.txt).
- // See: http://www.boost.org/doc/libs/release/libs/contract/doc/html/index.html
- #include <boost/contract.hpp>
- #include <cassert>
- //[static_public
- template<class C>
- class make {
- public:
- static void static_invariant() { // Static class invariants.
- BOOST_CONTRACT_ASSERT(instances() >= 0);
- }
- // Contract for a static public function.
- static int instances() {
- // Explicit template parameter `make` (check static invariants).
- boost::contract::check c = boost::contract::public_function<make>();
- return instances_; // Function body.
- }
- /* ... */
- //]
- make() : object() {
- boost::contract::old_ptr<int> old_instances =
- BOOST_CONTRACT_OLDOF(instances());
- boost::contract::check c = boost::contract::constructor(this)
- .postcondition([&] {
- BOOST_CONTRACT_ASSERT(instances() == *old_instances + 1);
- })
- ;
- ++instances_;
- }
- ~make() {
- boost::contract::old_ptr<int> old_instances =
- BOOST_CONTRACT_OLDOF(instances());
- boost::contract::check c = boost::contract::destructor(this)
- .postcondition([&] { // (An example of destructor postconditions.)
- BOOST_CONTRACT_ASSERT(instances() == *old_instances - 1);
- })
- ;
- --instances_;
- }
-
- C object;
- private:
- static int instances_;
- };
- template<class C>
- int make<C>::instances_ = 0;
- int main() {
- struct x {};
- make<x> x1, x2, x3;
- assert(make<x>::instances() == 3);
- return 0;
- }
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