This is a well known feature of Python. It's a very common "gotcha" to
new Python programmers.
Google "Mutable default parameters in Python" for long list of
explanations and fixes.
In short, don't use a mutable object as a default parameter.
Gary Herron
On 05/03/2018 12:47 PM, python-list@python.org wrote:
Hello,
I don't understand the behavior of the code below. Why does the dict property
"a" of both objects contain the same keys? This is only if "a=dict" is in
the initializer. If I put self.a = dict() into the init function, I get two
separate dicts
class Foo(object):
def __init__(self, x, a=dict()):
self.x = x
self.a = a
self.a[x] = x
c = Foo(1)
d = Foo(2)
print(c.__dict__)
print(d.__dict__)
robert
--
Dr. Gary Herron
Professor of Computer Science
DigiPen Institute of Technology
(425) 895-4418
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