forked from Light-City/CPlusPlusThings
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathdefault_delete.cpp
More file actions
107 lines (77 loc) · 2.35 KB
/
default_delete.cpp
File metadata and controls
107 lines (77 loc) · 2.35 KB
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
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
//
// Created by light on 19-11-3.
//
#include <iostream>
#include <complex>
using namespace std;
class Zoo {
public:
Zoo(int a, int b) : a(a), b(b) {
cout << "with param ctor \n";
}
Zoo() = default;
Zoo(const Zoo &) = delete; // copy ctor
Zoo(Zoo &&) = default; // move ctor
Zoo &operator=(const Zoo &) = default; // copy assignment
Zoo &operator=(const Zoo &&) = delete; // move assignment
// 一般函数可以使用=default或=delete?
// void fun1()= default; // error: ‘void Zoo::fun1()’ cannot be defaulted
void fun1() = delete; // compile ok
// 析构函数可以使用=default或=delete?
// ~Zoo()= delete; // ok,但是造成使用Zoo object出错
~Zoo() = default;
// 上述得出=delete可以使用在任何函数身上,而=default不可以使用在普通函数上
// 上述会联想到=0,=0只能用在virtual funciton上
private:
int a, b;
};
class Empty {
};
// 等价于 编译器给出的默认版本函数都是public且inline
class Empty1 {
public:
Empty1() {}
Empty1(const Empty1 &rhs) {}
~Empty1() {}
};
// no-copy
// copy ctor与copy assignment都delete掉
struct NoCopy {
NoCopy() = default;
NoCopy(const NoCopy &) = delete;
NoCopy &operator=(const NoCopy &) = delete;
~NoCopy() = default;
};
// no-dtor
struct NoDtor {
NoDtor() = default;
~NoDtor() = delete;
};
// 对no-copy的改进 将copy ctor与copy assignment 放到private ,但是可以对member与friend调用
// boost::noncopyable 就用到了PrivateCopy
class PrivateCopy {
private:
PrivateCopy(const PrivateCopy &) {};
PrivateCopy &operator=(const PrivateCopy &) {};
public:
PrivateCopy() = default;
~PrivateCopy() {};
};
// 继承了的都拥有PrivateCopy性质
class Foo : public PrivateCopy {
};
int main() {
Zoo z;
Zoo z1(1, 2);
// Zoo z2=z; // error copy ctor delete
z = z1;
complex<int> a; // 内部不带指针的可以不用写 big three 没有析构 有copy ctor与copy assignmetn 都是使用=default,没有自己写
string s; // 内部带指针的有big five
// NoDtor n; //error no-dtor 不能够自动delete
// NoDtor *p=new NoDtor; // ok
// delete p; // error no-dtor 不能够delete
Foo foo;
Foo foo1;
// foo = foo1; // 继承了的都拥有PrivateCopy性质
return 0;
}