April 12, 2019
Using Python's list()
—Using Python's list() function properly.
Got burned by a bug in a Python program. Forgot to copy a list and instead just assigned it a new name.
a = [ 1, 2 ]
b = a
b.pop(0)
b.append(3)
print a==b # Prints True!
print a # Prints [2, 3]
print b # Prints [2, 3]
To create a copy of a, I should have wrote b=list(a).
a = [ 1, 2 ]
b = list(a)
b.pop(0)
b.append(3)
print a==b # Prints False.
print a # Prints [1, 2]
print b # Prints [2, 3]
Bummer.
Found an article that explains this well. Python: copying a list the right way.
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