Functions

Functions allow us to not repeat ourselves and reuse things that our machines can do over again

Functions allow code reuse.
Defined with def, called/invoked with function name.
syntax = def(keyword) name the function(),

Parameters

Parameters are the name of the variables that we use. Define - Default parameters → pre-set values.

def say_hello(name = 'John doe', emoji = '^_^'):        #Default Parameters
    print(f"Helloo {name} {emoji}")

Arguments

Arguments are used as the actual values we provide to a function. Call, Invoke - Positional arguments → order matters. - Keyword arguments → specify by name.

say_hello()
say_hello('marwa', '<3')                              #Positional arguments
say_hello(emoji = '<3', name = "Aisha")               #Keyword arguments

print(say_hello)                                      #gives location of the memory

Return

Functions should return a value.

def sum1(num1, num2):
    return num1 + num2                 #returns whatever this expression gives us

# Should do one thing really well and return something
print(sum1(1, 2))

def sum2(num1, num2):           # Nested Functions
    def anotherFunc(n1, n2):
        return n1 + n2
    return anotherFunc(num1, num2)

total = sum2(1, 2)
print(total)

Methods vs Functions

Functions: independent (print(), max()).
Methods: tied to objects ('hello'.capitalize()).

built-in functions

print(), input(), list(), max(), min()

created functions

def some_function ():                        
    pass
some_function()

built-in methods

'helloooo'.capitalize()

args *kwargs

args can accept any number of positional arguments(tuple) *kwargs allow us to grab any number of keyword arguments and get a dictionary

Rule: params, *args, default parameters, kwargs (order of Parameters)**

def func1(*args):
    print(args)
    return sum(args)

print(func1(1,2,3,4,5))            #*args inside of this function is a tuple of arguments

def func2(**kwargs):
    total = 0
    for items in kwargs.values():
        total += items
    return total

print(func2(num1=5, num2=10))

def func3(*args, **kwargs):         #using args and kwargs to have n no. of arguments
    total = 0                       #creating variable for summing up
    for items in kwargs.values():   #looping, dictionary(kwargs) method(values)
        total += items              #adding dict values in the variable
    return sum(args) + total

print(func3(1,2,3,4,5, num1=5, num=10))

Doc Strings(''')

Special comments inside functions for documentation.
They are really useful to add comments and definitions to your functions

def test(a):
    '''
    Info: Docstring for test and prints param a
    '''
    print(a)

test('woah')          #to call a function
help(test)            #help to find out what a function does
print(test.__doc__)   #calling doc strings through methods

Practice Clean code

def is_even(num):
    return num % 2 == 0

print(is_even(74))