Writing a cli function that should do the following:
In case, the function parameters are not set (I get them from docopt), I would like to look them up from environment. The following does not work due to fast loading in functions:
def my_function(a=None, b=None, c=None):
for v in ("a", "b", "c"):
if vars()[v] is None:
locals()[v] = getenv("env_{}".format(v).upper())
do_something_with(a, b, c)
What would be the pythonic way to achieve this?
You can do this easily with keyword arguments:
def my_function(**kwargs):
for var in ('a', 'b', 'c'):
if kwargs.get(var) is None:
kwargs[var] = getenv("env_{}".format(v).upper())
do_something_with(**kwargs)
If you want to keep the signature, you can create a decorator (functools.wraps takes care of aligning the signatures):
def defaults_from_env(function):
@functools.wraps(function)
def wrapper(**kwargs):
for var in kwargs:
if kwargs.get(var) is None:
kwargs[var] = getenv("env_{}".format(var).upper())
return function(**kwargs)
return wrapper
@defaults_from_env
def my_function(a=None, b=None, c=None):
print(a, b, c)
However, this forces you to name all parameters when calling the decorated my_function (i.e. a=.., b=.., c=..). To avoid this, you could use inspect.signature to bind the parameters in the wrapper; this would allow you to get the name and value of all parameters, both *arg and **kwarg.
