FilesExpand file tree

 master

/

default_delete.cpp

Copy path

Blame

More file actions

Blame

More file actions

Latest commit

 

History

History

History

107 lines (77 loc) · 2.35 KB

 master

/

default_delete.cpp

Copy path

Top

File metadata and controls

• Code
• Blame

107 lines (77 loc) · 2.35 KB

Raw

Copy raw file

Download raw file

Open symbols panel

Edit and raw actions

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;

}