Requiring arguments to be passed as keyword arguments

[Duncan Booth]

mhagger at blizzard.harvard.edu (Michael Haggerty) wrote in 
<xj0zoxyjqwt.fsf at cyclone.harvard.edu>:

>Sometimes I would like to write functions with arguments that are
>REQUIRED to be passed as keyword arguments rather than positional
>arguments.  For example, for the following function I might want the
>second parameter to be passed as a keyword parameter:
>
>    f(1, 2) # Exception
>    f(1, variation=2) # OK
>

This is a kludge, but you can avoid accidental positional arguments if you 
stick in a tuple argument:
>>> def f(x, (donotuse,)=(None,), variation=57):
...     print "x=%s variation=%s" % (x, variation)
...
>>> f(1)
x=1 variation=57
>>> f(1,2)
Traceback (innermost last):
  File "<stdin>", line 1, in ?
  File "<stdin>", line 1, in f
TypeError: unpack non-sequence
>>> f(1, variation=2)
x=1 variation=2

This doesn't stop malicious use of positional arguments but it will fix the 
case you were asking about.

Wish list #1: A non-kludge way of doing this.
Wish list #2: A way to specify a default argument that cannot be changed 
when called.