So lets make a program that uses everything we’ve learned. Let’s make a todolist!

todos=[] #Make an empty list of our todos

Now to introduce a new way of programming in python

todos=[]

def main():
    #something will go here

if __name__ == '__main__':
    main()

We’ve seen the first part before, we’re just making a method called main that takes no parameters. The second part is a bit weird, though. What it’s saying is if some variable built-in to python is equal to __main__ call the main() method. Great so now lets add some input

todos=[]

def main():
    print("Welcome to your todolist!")
    print("When you're done entering your todos type 'Done!'")
    while(True):
        add_todo = raw_input("Name a thing you have to do: ")
        if "Done!" in add_todo:
            break


if __name__ == '__main__':
    main()

We use raw_input() for strings and input() for numbers

Okay so we’ve seen the first part before, were printing out some stuff to notify our user. We’ve seen a while loop before, but what’s in the parenthesis? We call that a boolean, the most simple variable in any programming language. A boolean is either True or False. We’ve actually been using booleans a lot, when we ask a question if it is True then it’ll do the next block of code else if it’s false it will do another thing. Next, we ask the user to input the name of their todo item. We then ask if the phrase “Done!” is in the user’s input. If it is, then break the while loop. Break is used to stop a while loop, if we didn’t have this, our program would go on forever! Now let’s make a todo item:

todos=[]

def main():
    print("Welcome to your todolist!")
    print("When you're done entering your todos type 'Done!'")
    while(True):
        add_todo = raw_input("Name a thing you have to do: ")
        if "Done!" in add_todo:
            break
        todos.append(make_todo(add_todo))


def make_todo(todo):
    due_date = raw_input("When is this due? ")
    category = raw_input("What category is this? ")
    return {
        "due_date": due_date,
        "category": category,
        "item": todo,
        "number": len(todos) + 1
    }


if __name__ == '__main__':
    main()

Great, so now we call the method make_todo to construct our item. Inside that method we ask the user for a due date and a category. We then return a dictionary with the corresponding keys and values for our items. We also give our item the key number so that we can keep track of which item is which. Every time we add an item to our todos, that number gets incremented. The dictionary returned by the method is then added as an item of the list. Now that we’ve made our todolist, lets print it out!

todos = []


def main():
    print("Welcome to your todolist!")
    print("When you're done entering your todos type 'Done!'")
    while(True):
        add_todo = raw_input("Name a thing you have to do: ")
        if "Done!" in add_todo:
            break
        todos.append(make_todo(add_todo))
    for todo in todos:
        print("Here is your {0} todo".format(todo["number"]))
        for key, value in todo.iteritems():
            print("The {0} is {1}".format(key, value))


def make_todo(todo):
    due_date = raw_input("When is this due? ")
    category = raw_input("What category is this? ")
    return {
        "due_date": due_date,
        "category": category,
        "item": todo,
        "number": len(todos) + 1
    }


if __name__ == '__main__':
    main()

In here we get each item in our todolist and print out which number todo it is. We then print out the keys and values for that todo item. If you want to add to this program, try making it so that after the items have been printed, the user can add or delete from this list. The final code for that will be posted at the bottom.

The first step I would take is breaking up the adding and printing parts of the program into methods so we the user can keep asking to use them.

def add_todo():
    print("When you're done entering your todos type 'Done!'")
    while(True):
        add_todo = raw_input("Name a thing you have to do: ")
        if "Done!" in add_todo:
            break
        todos.append(make_todo(add_todo))


def print_todos():
    print("--------------------")
    for todo in todos:
        print("Here is your {0} todo".format(todo["number"]))
        for key, value in todo.iteritems():
            print("The {0} is {1}".format(key, value))
        print("--------------------")

The add_todo() is called at the beggining of our program and then inside of a while loop so we can keep doing it as long as we want. The print_todos() is the same as before, but I added in some lines to make it more visually appealing.

def remove_todo():
    to_delete = input("Which todo have you completed? ") - 1
    todos.remove(to_delete)

Here’s the remove_todo() method which asks the user to remove a todo from their list. The issue with this is that once the todo item is deleted, the rest of the todolist’s numbers in the dictionary dont change. To fix that i made a method:

def remove_todo():
    to_delete = input("Which todo have you completed? ") - 1
    todos.remove(to_delete)
    reassign_numbers()


def reassign_numbers():
    for num in range(0, len(todos)):
        todos[num]["number"] = num + 1

All it does is go through and change the numbers of each todo.

Finally we put all the method calls in a while loop where we ask the user for their input:

def main():
    print("Welcome to your todolist!")
    add_todo()
    print_todos()
    while(True):
        choice = raw_input(
            "If you want to add to your list say 'add', if you want to remove things say 'remove', if you want to see your todos say 'print', say anything else to exit ")
        if 'add' in choice:
            add_todo()
        elif 'remove' in choice:
            remove_todo()
        elif 'print' in choice:
            print_todos()
        else:
            print("Thanks!")
            break

That’s it! Very simple all in all, hopefully you feel comfortable with basic python now. My next series is going to be with Swift, it’ll be a more difficult tutorial, going through more advanced concepts, but feel free to take a look! The entire code for this project is posted at the bottom in the gist