回答編集履歴
4
d
test
CHANGED
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@@ -68,6 +68,22 @@
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68
68
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69
69
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70
70
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71
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+
def __imul__(self, other):
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72
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+
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73
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+
self.x *= other
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74
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+
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75
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+
return self
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76
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+
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77
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+
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78
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+
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79
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+
def __iadd__(self, other):
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80
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+
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81
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+
self.x += other
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82
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+
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83
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+
return self
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84
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+
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85
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+
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86
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+
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71
87
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def __str__(self):
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72
88
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73
89
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return str(self.x)
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@@ -82,8 +98,16 @@
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82
98
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83
99
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z = x * 2 + 2
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84
100
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85
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-
print(y)
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101
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+
print(y)
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86
102
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103
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+
print(z)
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104
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+
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105
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+
x += 2
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106
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+
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107
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+
print(x) # 11
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108
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+
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109
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+
x *= 2
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110
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+
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87
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-
print(
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111
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+
print(x) # 22
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88
112
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89
113
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```
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3
d
test
CHANGED
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@@ -31,3 +31,59 @@
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31
31
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# 20
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32
32
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33
33
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```
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34
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+
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35
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+
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36
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+
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37
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+
## 補足
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38
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+
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39
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+
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40
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+
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41
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+
より汎用的なクラスを設計しようと思った場合、2倍にする関数だけでなく、3倍、4倍と任意の値を乗算したい場合も出てくるかもしれないので、演算子オーバロードを使うといいかもしれません。
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42
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+
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43
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+
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44
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+
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45
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+
[Python Tips：自作クラスの演算子のふるまいを定義したい - Life with Python](https://www.lifewithpython.com/2014/06/python-redefine-operators.html)
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46
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+
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47
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+
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48
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+
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49
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+
```python
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50
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+
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51
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+
class Hoge:
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52
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+
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53
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+
def __init__(self, x):
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54
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+
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55
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+
self.x = x
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56
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+
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57
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+
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58
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+
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59
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+
def __mul__(self, other):
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60
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+
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61
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+
return Hoge(self.x * other)
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62
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+
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63
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+
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64
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+
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65
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+
def __add__(self, other):
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66
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+
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67
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+
return Hoge(self.x + other)
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|
68
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+
|
|
69
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+
|
|
70
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+
|
|
71
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+
def __str__(self):
|
|
72
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+
|
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73
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+
return str(self.x)
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74
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+
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75
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+
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76
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+
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77
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+
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78
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+
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79
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+
x = Hoge(9)
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|
80
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+
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|
81
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+
y = x * 2
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|
82
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+
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83
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+
z = x * 2 + 2
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|
84
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+
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|
85
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+
print(y) # 18
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86
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+
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87
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+
print(z) # 20
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88
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+
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89
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+
```
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2
d
test
CHANGED
|
@@ -28,6 +28,6 @@
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28
28
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29
29
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times2_plus2(Hoge(9))
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30
30
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31
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-
#
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31
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+
# 20
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32
32
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33
33
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```
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1
s
test
CHANGED
|
@@ -1,8 +1,16 @@
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1
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-
times2_plus2()
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1
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+
自身のインスタンス変数と関係ない times2_plus2() がクラス Hoge のメソッドとして定義されているのは変な気がします。
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2
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+
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3
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+
フリー関数として定義してはどうでしょうか
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2
4
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3
5
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4
6
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5
7
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```python
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|
8
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+
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9
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+
def times2_plus2(y):
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10
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+
|
|
11
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+
return y.times2() + 2
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|
12
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+
|
|
13
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+
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6
14
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7
15
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class Hoge:
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8
16
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@@ -18,15 +26,7 @@
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18
26
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19
27
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20
28
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|
21
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-
def times2_plus2(self, y):
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22
|
-
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|
23
|
-
return y.times2() + 2
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|
24
|
-
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|
25
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-
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|
26
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-
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|
27
|
-
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|
28
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-
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|
29
|
-
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|
29
|
+
times2_plus2(Hoge(9))
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30
30
|
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|
31
31
|
# 9 * 2 + 2 = 18
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32
32
|
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