Dynamic default arguments in python functions

Question

I have a need for functions with default arguments that have to be set at function runtime (such as empty lists, values derived from other arguments or data taken from the d

Answer 1

A quick&dirty example implementation of something that might work:

class DynDefault(object):
    def __init__(self, callback):
        self.callback = callback
    def __call__(self):
        return self.callback()

def dyn_default(func):
    def wrapper(*args, **kw):
        args = [arg() for arg in args if isinstance(arg, DynDefault) else arg]
        for k, v in kw.items():
            if isinstance(v, DynDefault):
                kw[k] = v()
        return func(*args, **kw)
    return wrapper

@dyn_default
def foo(bar, baaz=DynDefault(blar)):
    # problem solved