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From: Peter Otten <__peter__@web.de>
Subject: Re: Meaning of * in the function arguments list
Date: Wed, 29 Oct 2014 10:13:12 +0100
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Xref: csiph.com comp.lang.python:79901

ast wrote:

> Consider the following to_bytes method from integer class:
> 
> int.to_bytes(length, byteorder, *, signed=False)
> 
> What doest the '*' in the arguments list means ?

A bare * indicates that the arguments that follow it are keyword-only:

>>> def f(a, b=2, *, c=3):
...     print("a = {}, b = {}, c = {}".format(a, b, c))
... 
>>> f(10)
a = 10, b = 2, c = 3
>>> f(10, 20)
a = 10, b = 20, c = 3
>>> f(10, 20, 30)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: f() takes from 1 to 2 positional arguments but 3 were given
>>> f(10, 20, c=30)
a = 10, b = 20, c = 30