In Python 3, m = [i] vs m[0] = i

在Python 3裡, assign是call by value? 還是call by reference呢？
Python自創了一個名詞，說是call by assignment.
但是從C語言學起的我，還是用call by value or call by reference來說明，會比較清楚。

如果i is integer, then:

case I:
m = [i]

case II:
m[0] = i

Q: 這兩者差在哪呢？
A:
case I:
m = [i], 是call by value, 也就是把m指向[i]位子的value。
case II:
m[0] = i, 是call by reference, 也就是把m[0]位子的值，設成i.

也許有人會覺得，出來的值都一樣，那有啥差別呢？
請看以下code:

class Solution:
    def byValue(self, t, m = [0]):
        print('m=', m)
        for i in t:
            m = [i]
        return m
    
    def byRef(self, t, m = [0]):
        print('m=', m)
        for i in t:
            m[0] = i
        return m
        
    def byValue1(self, t, m = 0):
        print('m=', m)
        for i in t:
            m = 1
        return m
    
    def byValue2(self, t, m = 0):
        print('m=', m)
        for i in t:
            m = 2
        return m
        
def main():
    a = Solution()
    
    print('byRef')
    print(a.byRef(['good']))
    print(a.byRef(['afternoon']))
    print('byValue')
    print(a.byValue(['fine.']))
    print(a.byValue(['thanks']))
    print('byValue1')
    print(a.byValue1(['good']))
    print(a.byValue1(['afternoon']))
    print('byValue2')
    print(a.byValue2(['fine.']))
    print(a.byValue2(['thanks']))
    
if __name__ == "__main__":
    main()

#會印出：
byRef
m= [0]
['good']
m= ['good']
['afternoon']
byValue
m= [0]
['fine.']
m= [0]
['thanks']
byValue1
m= 0
1
m= 0
1
byValue2
m= 0
2
m= 0
2