New submission from P Yap:
I have a function (test) with a list variable APP and declared its default as
an empty list [], while APP is not a global variable, if I execute the same
function multiple times, each time the APP will get appended. To workaround
this problem, I need to do APP.pop() inside the function or explicitly called
the function with an argument (test([])). del APP or reassign APP=[] inside the
function does not resolve the problem
same thing happens if the function is defined as an method inside a class.
Here is a little test program for testing:
def test(APP=[]):
if len(APP) == 0:
APP.append('1abc')
print "APP=", APP
APP.append('2def')
class test1 (object):
def t1(self, abc=[]):
abc.append('abc')
print abc
if __name__ == '__main__':
print "class test"
t = test1()
i = 0
while i < 3:
t.t1()
i += 1
print "Test function::"
i = 0
while i < 3:
test()
i += 1
Here are the output:
class test
['abc']
['abc', 'abc']
['abc', 'abc', 'abc']
Test function::
APP= ['1abc']
APP= ['1abc', '2def']
APP= ['1abc', '2def', '2def']
----------
components: Interpreter Core
messages: 236185
nosy: yappyta
priority: normal
severity: normal
status: open
title: A list arg with default value inside function got appended each time the
function is called
type: behavior
versions: Python 2.7
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue23478>
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