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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 <boost/optional.hpp>
#include <cassert>
//[named_override_pure_virtual_assert_false
template<typename T>
class generic_unary_pack {
public:
virtual void _1(T const& value, boost::contract::virtual_* v = 0) = 0;
virtual T _1(boost::contract::virtual_* v = 0) const = 0;
};
template<typename T>
void generic_unary_pack<T>::_1(T const& value, boost::contract::virtual_* v) {
boost::contract::check c = boost::contract::public_function(v, this)
.precondition([&] {
BOOST_CONTRACT_ASSERT(false); // Defer preconditions to overrides.
})
;
assert(false);
}
/* ... */
//]
template<typename T>
T generic_unary_pack<T>::_1(boost::contract::virtual_* v) const {
boost::optional<T> result; // Do not assume T has default constructor.
boost::contract::check c = boost::contract::public_function(v, result, this)
.postcondition([&] (boost::optional<T const&> const& result) {
BOOST_CONTRACT_ASSERT(*result == _1());
})
;
assert(false);
return *result;
}
//[named_override
template<typename T>
class positive_unary_pack
#define BASES public generic_unary_pack<T>
: BASES
{
public:
typedef BOOST_CONTRACT_BASE_TYPES(BASES) base_types;
#undef BASES
// BOOST_CONTRACT_OVERRIDE(_1) would generate reserved name `override__1`.
BOOST_CONTRACT_NAMED_OVERRIDE(override1, _1) // Generate `override1`.
virtual void _1(T const& value, boost::contract::virtual_* v = 0)
/* override */ {
// Use `override1` generated by BOOST_CONTRACT_NAMED_OVERRIDE above.
boost::contract::check c = boost::contract::public_function<override1>(
v,
static_cast<void (positive_unary_pack::*)(T const&,
boost::contract::virtual_*)>(&positive_unary_pack::_1),
this,
value
)
.precondition([&] {
BOOST_CONTRACT_ASSERT(value > 0);
})
;
value1_ = value;
}
/* ... */
//]
virtual T _1(boost::contract::virtual_* v = 0) const /* override */ {
T result; // Class default constructor already used T's default ctor.
boost::contract::check c = boost::contract::public_function<override1>(
v,
result,
static_cast<T (positive_unary_pack::*)(boost::contract::virtual_*)
const>(&positive_unary_pack::_1),
this
)
.postcondition([&] (T const& result) {
BOOST_CONTRACT_ASSERT(result > 0);
})
;
return result = value1_;
}
private:
T value1_;
};
int main() {
positive_unary_pack<int> u;
u._1(123);
assert(u._1() == 123);
return 0;
}
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