How do I make a copy of a list in a function using slice in Python?

Question

I have two lists where I want to pop elements from one list into the other one. I'm trying to use a [:] slice to make a copy since t don't want to modify the original list.

Why do I get an invalid syntax error?

def make_great(original_list[:], copy = []):
    tmp = original_list.pop()
    copy.append(tmp)

def show_magicians(ls = []):
    for i in ls:
    print ("our next magician is "+i+" !")

magician_list = ['daniel', 'david', 'sara', 'jose', 'maria', 'miriam']
show_magicians(magician_list)

Error message:

 ~/Python/function/ $ python p.py
  File "/home/ubuntu/Python/function/p.py", line 2
     def make_great(original_list[:], copy):
     SyntaxError: invalid syntax

Answer 1

You have 2 options for making a shallow copy of a list in Python 3.

Either:

listB = listA[:]

...or...

listB = listA.copy()

Answer 2

You can not add [:] to the argument in the definition of make_great: An argument is just a name of a value, but not a computation. For example, you also could not write

def foo(bar + 1):
     code...

Thus, you have to use the '[:]' at the place where you call make_great, like

make_great(list_to_be_copied[:], ...)

or you create the copy within make_great, like

def make_great(original_list, copy = []):
    copy_of_orig_list = original_list[:]
    ...

Also, it seems that the argument copy shall take the result? In that case it would not make much sense to have it as a default argument. Also note the comment about default arguments with mutable values. You should consider returning the result.