especially when there are so many parameters (10+ 20+).
What are good ways of enforcing required/optional parameters to a function?
What are some good books that deal with this kind of questions for python?
(like effective c++ for c++)
** EDIT **
I think it's very unpractical to list def foo(self, arg1, arg2, arg3, .. arg20, .....): when there are so many required parameters.
Parameters can be required or optional depending on how they appear in the function definition:
def myfunction(p1, p2, p3=False, p4=5)
In this definition, parameters p1 and p2 are required. p3 is optional and will acquire the value False if not provided by the caller. p4 is also optional and will acquire the value 5 if not provided.
If you really need to pass ten or more parameters into a function, it might be better to pass them as a dictionary:
args = {'a': something, 'b': something_else, 'c': 5, 'd': 99.99, ... }
myfunc(args)
dict if there are a number of (variable) args, this would make understanding code much harder and more error prone. I would use *args or **kwargs, then you can then mix required and optional.If a function parameter is not required, you can set it equal to None.
def hello(first_name, last_name=None):
print "Hello " + first_name
Or as John Gordon said, you can set a parameter with a default value the same way.
Note that optional parameters need to be defined after the required parameters.
You can denote required keyword argument as follows:
def myfunc(positional_arg, *, required_kwarg, optional_kwarg=None, **other_kwargs):
pass
One way is to have your required parameters be named like func(a, b, c=1) and this would denote required because the code will error out at runtime if missing any. Then for the optional parameters you would then use Python's args and kwargs.
Of course anytime you use Python's args and kwargs means additional code to pull the parameter from the args and kwargs.
Additionally for each combination of optional parameters you then would need to code a bunch of conditional control flow.
In addition you don't want too many optional assignments because it makes the code's API to complex to describe... and the control flow have to many lines of code because the number of possible combinations grows very quickly for each additional optional parameter.
AND your test code grows EVEN faster...
importerthat imports product data from excel sheet. It goes over +10 easily. How do you suppose to break them?