Simplifying function with keyword only arguments

Picture this: you’re working with some legacy code; it has juggling multiple positional arguments passed to a function. Now you are mapping arguments to its value 🗺️ It’s like trying to catch falling knives blindfolded! 🤹‍♂️

The Original Function

def validate_document(name, size, path, doc_type, owner, category, date, issue_by):
    print(f'name: {name}, size: {size}, path: {path}, doc_type: {doc_type}, owner: {owner}, category: {category}, date: {date}, issue_by: {issue_by}')

# Function call with positional argument
validate_document('test.pdf', 1024, 'home/user/', 'pdf', 'Bob', 'medical', '2023-01-02', 'Martin')

It's difficult to work with 🥲, right?

Worry not 😉, you can refactor it to make it better, using keyword only arguments.

Using "*" in function declaration, make sure that all the following arguments will be passed as keyword argument only.

Now your Improved code look like this

def validate_document(name, *, size, path, doc_type, owner, category, date, issue_by):
    print(f'name: {name}, size: {size}, path: {path}, doc_type: {doc_type}, owner: {owner}, category: {category}, date: {date}, issue_by: {issue_by}')

# function called with keyword only arguments
validate_document(name='test.pdf', size=1024, path='home/user/', doc_type='pdf', owner='Bob', category='medical', date='2023-01-02', issue_by='Martin')

Now, only the “name” can venture forth as a positional argument, because it is before "*". The rest arguments must be called by their true names: size, path, doc_type, and so on. 🗝️

If you still try to call function with positional argument you will encounter TypeErorr like following.

TypeError: validate_document() takes 1 positional argument but x were given

Now you have better code to work with which 😇

And Happy Coding!