1 //////////////////////////////////////////////////////////////////////////////
2 //
3 // (C) Copyright Ion Gaztanaga 2014-2014.
4 // Distributed under the Boost Software License, Version 1.0.
5 // (See accompanying file LICENSE_1_0.txt or copy at
6 // http://www.boost.org/LICENSE_1_0.txt)
7 //
8 // See http://www.boost.org/libs/move for documentation.
9 //
10 //////////////////////////////////////////////////////////////////////////////
11 
12 #include <boost/move/detail/meta_utils_core.hpp>
13 
14 #include <boost/move/move.hpp>
15 
16 //[template_assign_example_foo_bar
17 
18 class Foo
19 {
20    BOOST_COPYABLE_AND_MOVABLE(Foo)
21 
22    public:
23    int i;
Foo(int val)24    explicit Foo(int val)      : i(val)   {}
25 
Foo(BOOST_RV_REF (Foo)obj)26    Foo(BOOST_RV_REF(Foo) obj) : i(obj.i) {}
27 
operator =(BOOST_RV_REF (Foo)rhs)28    Foo& operator=(BOOST_RV_REF(Foo) rhs)
29    {  i = rhs.i; rhs.i = 0; return *this; }
30 
operator =(BOOST_COPY_ASSIGN_REF (Foo)rhs)31    Foo& operator=(BOOST_COPY_ASSIGN_REF(Foo) rhs)
32    {  i = rhs.i; return *this;   } //(1)
33 
34    template<class U> //(*) TEMPLATED ASSIGNMENT, potential problem
35    //<-
36    #if 1
37    typename ::boost::move_detail::disable_if_same<U, Foo, Foo&>::type
operator =(const U & rhs)38    operator=(const U& rhs)
39    #else
40    //->
41    Foo& operator=(const U& rhs)
42    //<-
43    #endif
44    //->
45    {  i = -rhs.i; return *this;  } //(2)
46 };
47 //]
48 
49 struct Bar
50 {
51    int i;
BarBar52    explicit Bar(int val) : i(val) {}
53 };
54 
55 
56 //<-
57 #ifdef NDEBUG
58 #undef NDEBUG
59 #endif
60 //->
61 #include <cassert>
62 
main()63 int main()
64 {
65 //[template_assign_example_main
66    Foo foo1(1);
67    //<-
68    assert(foo1.i == 1);
69    //->
70    Foo foo2(2);
71    //<-
72    assert(foo2.i == 2);
73    Bar bar(3);
74    assert(bar.i == 3);
75    //->
76    foo2 = foo1; // Calls (1) in C++11 but (2) in C++98
77    //<-
78    assert(foo2.i == 1);
79    assert(foo1.i == 1); //Fails in C++98 unless workaround is applied
80    foo1 = bar;
81    assert(foo1.i == -3);
82    foo2 = boost::move(foo1);
83    assert(foo1.i == 0);
84    assert(foo2.i == -3);
85    //->
86    const Foo foo5(5);
87    foo2 = foo5; // Calls (1) in C++11 but (2) in C++98
88    //<-
89    assert(foo2.i == 5); //Fails in C++98 unless workaround is applied
90    assert(foo5.i == 5);
91    //->
92 //]
93    return 0;
94 }
95 
96