1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
|
// 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
//[mitchell02_observer
#ifndef OBSERVER_HPP_
#define OBSERVER_HPP_
#include <boost/contract.hpp>
#include <cassert>
// Observer.
class observer {
friend class subject;
public:
// No inv and no bases so contracts optional if no pre, post, and override.
/* Creation */
observer() {
// Could have omitted contracts here (nothing to check).
boost::contract::check c = boost::contract::constructor(this);
}
virtual ~observer() {
// Could have omitted contracts here (nothing to check).
boost::contract::check c = boost::contract::destructor(this);
}
/* Commands */
// If up-to-date with related subject.
virtual bool up_to_date_with_subject(boost::contract::virtual_* v = 0)
const = 0;
// Update this observer.
virtual void update(boost::contract::virtual_* v = 0) = 0;
};
bool observer::up_to_date_with_subject(boost::contract::virtual_* v) const {
boost::contract::check c = boost::contract::public_function(v, this);
assert(false);
return false;
}
void observer::update(boost::contract::virtual_* v) {
boost::contract::check c = boost::contract::public_function(v, this)
.postcondition([&] {
BOOST_CONTRACT_ASSERT(up_to_date_with_subject()); // Up-to-date.
})
;
assert(false);
}
#endif // #include guard
//]
|
