Why does the example use an unpacked keyword parameter before a named one?

Frequently Asked Questions Python FAQ
1

Confused on part 12. It says calls must be made in this order:

  • All named positional parameters
  • An unpacked positional parameter ( *args )
  • All named keyword parameters
  • An unpacked keyword parameter ( **kwargs )

but in the example, the **kwargs call happens 3rd, and then the keyword parameter comes 4th:

main("files/users/userslist.txt", 
     "-d", 
     "-a", 
     save_all_records=True, 
     user_list=current_users)

Am I going crazy or is this a mistake?

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2

@chip2653472605, Good pick - up!

As it turns out, the named (i.e., default) keyword argument and the **kwargs arguments can be interchanged in the function call. The only hard-and-fast rule is positional before named. But the interpreter is smart enough to sort out the named parameter from the keys in the **kwargs parameters.

You can play around with this in the accompanying exercise, where the default provided function header is this:
def remove(filename, *args, **kwargs):
… and the provided function call is this:
print(remove("text.txt", "generous", "gallant", fond="amused by", Robin="Mr. Robin"))

Once you get the function running, to the suggested parameters in the exercise, add this one title = "Robin Hood"
… and place it in the function definition just before **kwargs:, like this:
def remove(filename, *args, title = "Robin Hood", **kwargs):
… and then immediately before the return statement in the function body, put
text = title + "\n" + text

Now, when you run the function, the printed text will be headed by the title, Robin Hood

So, here you go: Change the function call to this

  • print(remove(“text.txt”, “generous”, “gallant”, title = “New Story”, fond=“amused by”, Robin=“Mr. Robin”))

… or this

  • print(remove(“text.txt”, “generous”, “gallant”, fond=“amused by”, title = “New Story”, Robin=“Mr. Robin”))

… or this:

  • print(remove(“text.txt”, “generous”, “gallant”, fond=“amused by”, Robin=“Mr. Robin”, title = “New Story” ))

… and it will work with the named keyword parameter before, after, or in between the **kwargs!

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