Variable assignment inside a function argument

Question

def auto_detect_serial_unix(preferred_list=['*']):

What happens to the argument when this function gets called?

You need to read [the Python tutorial](https://docs.python.org/3/tutorial/controlflow.html#default-argument-values). — BrenBarn, Jul 18 '16 at 03:30
Possible duplicate of [Default Values for function parameters in Python](http://stackoverflow.com/questions/13195989/default-values-for-function-parameters-in-python) — OneCricketeer, Jul 18 '16 at 03:30

score 0 · Answer 1 · answered Jul 18 '16 at 03:35

If nothing is passed in to auto_detect_serial_unix, then preferred_list is set to ['*']. Otherwise, what you pass in is set to preferred_list:

>>> def auto_detect_serial_unix(preferred_list=['*']):
...     print preferred_list
... 
>>> auto_detect_serial_unix()
['*']
>>> auto_detect_serial_unix(['new', 'list'])
['new', 'list']
>>>

score 0 · Answer 2 · answered Jul 18 '16 at 03:35

0

If auto_detect_serial_unix is called with an argument, then preferred_list will have the value of that argument.

Otherwise, if auto_detect_serial_unix is called with no arguments, then preferred_list will have the given default value.

answered Jul 18 '16 at 03:35

John Gordon

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Variable assignment inside a function argument

2 Answers2