Varying Arguments¶
In Python we can pass different number of arguments of same type while invoking functions. Let’s talk about Varying arguments.
- At times we might want to pass values of same type as arguments and we might not know how many of them.
- In that scenario we can leverage the concept of Varying arguments.
- The parameter which accepts Varying arguments should have
*at the beginning – example:*phone_numbers. - As part of the function body the type of the parameter will be
tuple. In our case, as we will be passing phone numbers as strings, it will be of typetuplewhere each element will be of type string.
In [1]:
def get_invalid_phone_count(*phone_numbers, employee_id):
invalid_count = 0
for phone_number in phone_numbers:
if len(phone_number) < 10:
invalid_count += 1
return employee_id, invalid_count
In [2]:
s = 'Employee {employee_id} have {invalid_count} invalid phones'
employee_id, invalid_count = get_invalid_phone_count('1234', '1234567890', 1)
# argument by position will fail
# Python interpreter cannot determine whether 1 is related to phone_numbers or employee_id
--------------------------------------------------------------------------- TypeError Traceback (most recent call last) Input In [2], in <cell line: 2>() 1 s = 'Employee {employee_id} have {invalid_count} invalid phones' ----> 2 employee_id, invalid_count = get_invalid_phone_count('1234', '1234567890', 1) TypeError: get_invalid_phone_count() missing 1 required keyword-only argument: 'employee_id'
In [3]:
s = 'Employee {employee_id} have {invalid_count} invalid phones'
phone_numbers = ('1234', '1234567890',)
employee_id, invalid_count = get_invalid_phone_count(employee_id=1, phone_numbers=phone_numbers)
# argument by name will fail
# This will fail as we cannot pass varrying argument using keyword
--------------------------------------------------------------------------- TypeError Traceback (most recent call last) Input In [3], in <cell line: 3>() 1 s = 'Employee {employee_id} have {invalid_count} invalid phones' 2 phone_numbers = ('1234', '1234567890',) ----> 3 employee_id, invalid_count = get_invalid_phone_count(employee_id=1, phone_numbers=phone_numbers) TypeError: get_invalid_phone_count() got an unexpected keyword argument 'phone_numbers'
In [4]:
s = 'Employee {employee_id} have {invalid_count} invalid phones'
employee_id, invalid_count = get_invalid_phone_count('1234', '1234567890', employee_id=1)
# argument by position will fail
# Python interpreter cannot determine whether 1 is related to phone_numbers or employee_id
In [5]:
print(s.format(employee_id=employee_id, invalid_count=invalid_count))
Employee 1 have 1 invalid phones
In [6]:
def get_invalid_phone_count(employee_id, *phone_numbers):
print(f'Length of phone_numbers is: {len(phone_numbers)}')
print(f'Type of phone_numbers is: {type(phone_numbers)}')
print(f'Type of each phone number is: {type(phone_numbers[0])}')
print(phone_numbers)
invalid_count = 0
for phone_number in phone_numbers:
if len(phone_number) < 10:
invalid_count += 1
return employee_id, invalid_count
In [7]:
s = 'Employee {employee_id} have {invalid_count} invalid phones'
employee_id, invalid_count = get_invalid_phone_count(1, '1234', '1234567890') # argument by position works here
Length of phone_numbers is: 2
Type of phone_numbers is: <class 'tuple'>
Type of each phone number is: <class 'str'>
('1234', '1234567890')
In [8]:
print(s.format(employee_id=employee_id, invalid_count=invalid_count))
Employee 1 have 1 invalid phones
In [9]:
s = 'Employee {employee_id} have {invalid_count} invalid phones'
phone_numbers = ['1234', '1234567890']
In [10]:
employee_id, invalid_count = get_invalid_phone_count(1, *phone_numbers) # argument by position works here
Length of phone_numbers is: 2
Type of phone_numbers is: <class 'tuple'>
Type of each phone number is: <class 'str'>
('1234', '1234567890')
In [11]:
print(s.format(employee_id=employee_id, invalid_count=invalid_count))
Employee 1 have 1 invalid phones