Functions.py

# Sometimes we copy and paste our code

import datetime
# print timestamps to see how long sections of code
# take to run

first_name = 'Susan'
print('task completed') # Copy
print(datetime.datetime.now()) # Copy
print() # Copy

for x in range(0,10):
    print(x)
print('task completed') # Paste
print(datetime.datetime.now()) # Paste
print() # Paste

# Use functions instead of repeating code

import datetime
# Print the current time
def print_time():
    print('task completed')
    print(datetime.datetime.now())
    print()

first_name = 'Susan'
print_time()

for x in range(0,10):
    print(x)
print_time()

# By moving the code to a function. you reduce rework and the chance of introducing bugs when you change the code you had copied

# Import the datetime class from datetime library
from datetime import datetime # It is ameliorated in contrast to the above codes
# Print the current time
def print_time():
    print('task completed')
    # Now I don't need the extra datetime prefix
    print(datetime.now()) # It is ameliorated in contrast to the above codes
    print()

first_name = 'Susan'
print_time()

for x in range(0,10):
    print(x)
print_time()

# What if I want a different message displayed?

from datetime import datetime
# print timestamps to see how long sections of code
# take to run

first_name = 'Susan'
print('first name assigned') # It is changed
print(datetime.now())
print()

for x in range (0,10):
    print(x)
print('loop completed') # It is changed
print(datetime.now())
print() 

# Pass the task name as a parameter

from datetime import datetime

# Print the current time and task name
def print_time(task_name):
    print(task_name)
    print(datetime.now())
    print()

first_name = 'Susan'
print_time('first name assigned')

for x in range (0,10):
    print(x)
print_time('loop completed')

# Here's another example where the code looks different but we are doing the same logic over and over

first_name = input('Enter your first name: ')
first_name_initial = first_name[0:1]
last_name = input('Enter your last name: ')
last_name_initial = last_name[0:1]

print('Your initials are: '+ first_name_initial \
    + last_name_initial)

# I can still use a function, but this time my function returns a value

def get_initial(name):
    initial = name [0:1]
    return initial

first_name = input('Enter your first name: ')
first_name_initial = get_initial(first_name)

last_name = input('Enter your last name: ')
last_name_initial = get_initial(last_name)

print('Your initials are: ' + first_name_initial \
    + last_name_initial)

# If you need to change something you only have to change it in one place!

def get_initial(name):
    initial = name [0:1].upper() # This is where I can capitalize initials with UPPER() command
    return initial

first_name = input('Enter your first name: ')
first_name_initial = get_initial(first_name)

last_name = input('Enter your last name: ')
last_name_initial = get_initial(last_name)

print('Your initials are: ' + first_name_initial \
    + last_name_initial)

# Functions that returns values allow clever code, but you might trade readability for less code

def get_initial(name):
    initial = name[0:1].upper()
    return initial

first_name = input('Enter your first name: ')
last_name = input('Enter your last name: ')

print('Your initials are: '\
    + get_initial(first_name) \
    + get_initial(last_name))

# Functions make your code more readable and easier to maintain
# Always add comments to explain the purpose of your functions
# Functions must be declared before the line of code where the function is called