Python keyword arguments referencing each other

Question

When I try the following I get an error

def test_func(key1=2.7, key2=key1*3.5):
    print(key1, key2)

NameError: name 'key1' is not defined

My solution would be something like

def test_func(key1=2.7, key2=None):
    if not key2:
        key2 = key1*3.5

    print(key1, key2)

but this looks kind of ugly to me. Does anybody have a better solution?

edit:

so my final solution is

def test_func(key1=2.7, key2=None):
    if key2 is not None:
        key2 = key1*3.5

    print(key1, key2)

thanks for all answers

Answer 1

Nope, there is no better solution.

Function argument definitions can be expressions, but they are evaluated only once (which sometimes surprises people, see "Least Astonishment" and the Mutable Default Argument).

Answer 2

My solution would be:

def t(key1=1, **kwargs):
    key2 = kwargs.get('key2', key1*2.7)

getting key2 from kwargs and get data from it with the default key1*2.7