PythonTrainingExercises/Beginners/ExampleFunctions/C_functions_default_mutable.py at 13d142f9900ad82262dbc53364bbb9cb6ecda170 · man-group/PythonTrainingExercises · GitHub

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
#!/usr/bin/env python
"""Does...

Created on Aug 25, 2011

@author: paulross
"""

__author__  = 'Paul Ross'
__date__    = '2011-08-03'
__version__ = '0.1.0'
__rights__  = 'Copyright (c) 2011 Paul Ross.'

################################
# Problem with mutable defaults.
################################
def defaultMutableCatch(a=[1,]):
    a.append('Ooops')
    return a

x = [1,]

def defaultMutableFix(a=x):
    if a is None:
        a = []
    a.append('Ooops')
    return a

def main():
    # defaultMutableCatch()
    print('defaultMutableCatch():', defaultMutableCatch())
    print('defaultMutableCatch():', defaultMutableCatch([]))
    print('defaultMutableCatch():', defaultMutableCatch())
    # defaultMutableFix()
    print('defaultMutableFix():', defaultMutableFix())
    print('defaultMutableFix():', defaultMutableFix())
    print('defaultMutableFix():', defaultMutableFix())

if __name__ == '__main__':
    main()
#####################################
# END: Problem with mutable defaults.
#####################################