Functions in Karel - Python

Summary

This lesson delves into the importance and mechanics of functions in programming with Carol. Functions are essential for breaking down complex problems, enhancing code readability, and avoiding code repetition. The video script teaches how to define and name functions effectively, using 'def' and following naming conventions like snake case. It distinguishes between defining a function and calling it to execute commands, illustrating the process with a practical example of teaching Carol to 'turn around'. The lesson emphasizes the significance of functions in programming and computer science, encouraging learners to practice defining and calling their own functions.

Takeaways

• 📘 Functions are a way to teach Carol (presumably a programming environment or robot) new commands or actions.
• 🔍 Functions help break down problems into smaller, more manageable parts, making problem-solving easier.
• 📝 Using functions can make code more understandable, which is crucial when working as part of a team.
• 🔁 Functions prevent the need for repeating code, promoting efficiency and reducing errors.
• 🛠 The purpose of programming is to teach computers new things, and functions are a fundamental part of this process.
• 📝 The general format for writing a function in Carol includes using the 'def' keyword, followed by a descriptive name.
• 🔑 Function names should start with a letter, be in lowercase, and use underscores to separate words (snake case).
• 🎯 Function names should be descriptive, starting with an action verb to indicate what the function does.
• 🤖 Defining a function is like teaching Carol a new word, but calling the function is what makes Carol execute the action.
• 📑 In Python, the function definition must appear before the call statement in the code.
• 🔄 Once a function is defined, it can be called multiple times without needing to redefine it, allowing for repeated actions.

Q & A

What is the primary purpose of using functions in programming?

The primary purpose of using functions in programming is to break a problem into smaller parts, making it easier to solve, and to avoid repeating code, which simplifies problem-solving and makes the code easier to understand and maintain.

Why is it important to use functions when working as part of a team on a coding project?

Using functions is important in a team setting because it helps ensure that the code is readable and understandable by others, which is crucial for collaboration and maintenance of the codebase.

What is the general format for writing a function in Carol?

The general format for writing a function in Carol starts with the keyword 'def' for define, followed by the function name, which should be descriptive and follow naming conventions such as snake case, and then a colon. The function's body, which contains the commands, is indented.

What are the basic rules for naming functions in Carol?

The basic rules for naming functions in Carol include starting the name with a letter, using all lowercase letters, separating words with underscores (snake case), and starting with an action verb that describes what the function does.

What is the difference between defining a function and calling a function in Carol?

Defining a function in Carol is like teaching it a new word or command, but it doesn't execute the command. Calling a function is the act of instructing Carol to execute the command associated with the function.

Why is it necessary to define a function before calling it in Python?

In Python, a function must be defined before it can be called because the interpreter needs to know about the function's existence and structure before it can execute its commands.

What does the keyword 'def' stand for in the context of defining a function in Carol?

The keyword 'def' stands for 'define', which is used to declare the start of a function definition in Carol.

How can you make a function name in Carol more descriptive?

A function name in Carol can be made more descriptive by starting with an action verb, using lowercase letters, separating words with underscores, and ensuring the name clearly communicates the function's purpose.

What is the significance of using snake case for function names in Carol?

Using snake case for function names in Carol improves readability by clearly separating words within the function name, making it easier to understand the function's purpose at a glance.

Can you provide an example of a poorly named function and how it could be improved based on the script?

An example of a poorly named function from the script is 'blahblah', which is not descriptive. It could be improved to something like 'take_four_balls', which clearly communicates the action the function is meant to perform.

How does the script demonstrate the process of teaching Carol a new command and then executing it?

The script demonstrates this process by first defining a function called 'turnaround' with the necessary commands for Carol to turn around. Then, it shows how to call this function multiple times in the code to execute the turn around action without needing to redefine the function.

Outlines

00:00

📘 Understanding Functions in Carol

This paragraph introduces the concept of functions in the context of programming with Carol. Functions are likened to teaching Carol new words, serving to break down complex problems into manageable parts, simplifying the coding process and enhancing code readability. The paragraph emphasizes the importance of functions in programming, as they not only aid in problem-solving but also facilitate collaboration by making code more understandable to others. The general format for writing a function in Carol is outlined, starting with the 'def' keyword, followed by a descriptive and action-oriented function name. Naming conventions, such as using lowercase letters and underscores to separate words (snake case), are also discussed. Examples are provided to illustrate good function naming practices.

05:01

🔄 Function Definition and Execution in Carol

This paragraph delves deeper into the distinction between defining and calling functions in Carol, akin to teaching a new word versus instructing its use. The process of defining a function with the 'def' keyword is reiterated, with a focus on the importance of placing the function definition before its call in the code. An exercise is introduced where the task is to teach Carol a 'turnaround' command, demonstrating how to structure the function with descriptive action verbs and indentation. The paragraph clarifies that defining a function does not execute it; the function must be called to perform the associated actions. The exercise concludes with a practical demonstration of defining and calling the 'turnaround' function multiple times without redefinition, showcasing the efficiency and reusability of functions in programming.

Keywords

💡functions

Functions are a fundamental concept in programming, serving as reusable blocks of code that perform a specific task. In the context of the video, functions are used to teach 'Carol' (presumably a program or AI) new actions, making the code more modular and easier to understand. The script emphasizes the importance of functions in breaking down complex problems into smaller, more manageable parts, and in avoiding code repetition.

💡problem-solving

Problem-solving is the process of finding solutions to issues or challenges. The video script discusses how using functions can simplify the problem-solving aspect of programming by allowing programmers to tackle smaller parts of a larger problem individually. This approach makes complex tasks more approachable and comprehensible.

💡code readability

Code readability refers to how easily humans can understand the code. The script highlights the importance of using functions to make code more understandable, which is crucial when working in a team setting. Readable code allows other programmers to quickly grasp the purpose and functionality of the code segments.

💡programming languages

Programming languages are formal languages designed to communicate instructions to a computer. The script mentions that all programming languages support the creation of functions, emphasizing their universal role in teaching computers new tasks and facilitating the programming process.

💡def keyword

In many programming languages, 'def' is a keyword used to define a function. The script explains that starting a function definition with 'def' is a way to signal to the programming language that a new function is being created, and it is followed by the function's name and a colon.

💡function naming

Function naming is the process of assigning a descriptive name to a function, which should clearly communicate its purpose. The script provides guidelines for naming functions, such as starting with a letter, using lowercase letters, and separating words with underscores (snake case). Good function names are descriptive and start with an action verb.

💡snake case

Snake case is a naming convention where words are separated by underscores and all letters are lowercase. It is often used in programming for variable names and function names to enhance readability. The script mentions snake case as the recommended naming style for functions.

💡action verb

An action verb is a type of verb that expresses an action or occurrence. In the context of function naming, the script suggests that functions should start with an action verb to clearly indicate the action that the function performs, such as 'turn' in 'turn left'.

💡function definition

Function definition is the process of specifying the structure and behavior of a function in code. The script explains that defining a function is like teaching Carol a new word, but it doesn't execute any action until the function is called. The definition includes the function's name, parameters (if any), and the block of code that will be executed when the function is called.

💡function call

A function call is the act of executing a function in code. The script illustrates that after a function is defined, it must be called to perform its action. Calling a function is like instructing Carol to execute the command that was previously defined.

💡indentation

Indentation in programming refers to the use of whitespace to delimit blocks of code. The script points out that commands within a function must be indented to indicate that they are part of the function's body. The end of the indentation marks the end of the function definition.

Highlights

Functions in Carol are a method to teach the system new words or commands.

Functions help break problems into smaller parts, simplifying the problem-solving process.

Using functions makes code easier to understand, which is crucial for team coding projects.

Functions prevent code repetition, enhancing efficiency in programming.

Functions are a fundamental part of programming and computer science.

The general format of a function in Carol starts with the 'def' keyword for define.

Function names should be clear, descriptive, and follow basic naming conventions like snake case.

Names should start with an action verb and sound like a command for clarity.

Examples of good function names include 'spin_twice' and 'turn_right', which are descriptive and start with action verbs.

Poor function names like 'five_moves' or 'blahblah' lack descriptiveness and clarity.

Renaming 'five_moves' to 'move_five_times' and 'tower' to 'build_tower' improves descriptiveness.

The distinction between defining and calling a function is crucial; defining teaches but does not execute.

Calling a function is necessary to execute its commands, like instructing Carol to perform an action.

In Python, functions must be defined before they can be called in the code.

An example function 'turnaround' is defined and then called multiple times without redefinition.

Functions can be called repeatedly to perform actions without rewriting the code.

The exercise concludes with teaching Carol to 'turnaround' and calling this function to achieve the desired outcome.

Transcripts

in this lesson we're going to keep

talking about functions in Carol as you

may recall from the last lesson

functions are a way to teach Carol a new

word so why do we use functions well

there are several reasons first it helps

break our problem into smaller parts

oftentimes if we can separate our

program into smaller parts it can make

the problem solving aspect easier we can

also use functions to make our code

easier to understand finally we can use

functions so that we don't have to

repeat code if we want to turn write

several times in our program we don't

want to have to keep typing turn left

three times over and over so again

breaking our code into smaller parts

simplifies the problem-solving aspect

and can make it easier for us to solve

instead of trying to solve an entire

problem at once we are able to solve

small pieces of a larger problem using

functions also makes it easier for you

and others to understand your code most

the time on large coding projects you're

working as part of a team of coders it's

important that others can read and

understand your code and functions can

help us do that so functions are one of

the most important parts of programming

the purpose of program is really just to

teach a computer new things and that's

exactly what functions are doing so

functions are making it easier for us to

program and easier for others to read

our programs and thus easier for us to

teach a computer new ways to do things

so functions are really a key building

block for all of computer science in

fact all programming languages that you

write functions so let's take a look at

writing functions in Carol in this

general format of a function remember we

start all our functions using the

keyword def for define next we give it a

name naming is crucial we want our names

to make it clear what the function is

doing using a name like my function may

not tell us much but when we use names

like TURN RIGHT we have a pretty good

idea what that function is

doing when we name our functions we

should follow a few basic rules so first

our name should start with a letter and

cannot have any spaces in it a second

all of our letters should be lowercase

and words should be separated with an

underscore this is commonly referred to

as snake case the name should describe

what the function is doing and the name

should start with an action verb and

sound like a command so let's take a

look at some examples so at the top we

can see a few examples of functions that

are good you built our spin twice they

both start with action verbs and are

pretty descriptive the second bow teller

also starts with an action verb but the

two words should be separated by an

underscore okay so that looks better now

five moves is descriptive but it doesn't

start with a letter and it doesn't have

an action verb as our first word so

let's change this to move five times so

tower can work as a function but it

doesn't really have that action

associated with it so let's change that

one to build tower as well

finally our blahblah function is just

not descriptive it doesn't tell us

anything about what it might do which

can make it hard for us to read our

programs and also hard to remember what

that function is used for so let's

change that one to something like take

four balls you know take four balls

tells us immediately what that function

is doing okay so we've taken a look at

creating and naming our functions but

there's an important distinction we need

to make defining is like teaching Cairo

a new word but Cairo doesn't actually do

anything when we define the word

we need to call the function to get

Carol to actually execute them command

another way to think about it is

defining a function is like writing the

instructions for a new action but when

we want that action to happen we need to

call the function calling the function

causes the action to happen let's take a

look at an example where we create a

function called turnaround we can define

the function this is like teaching Carol

the new command to turn around but just

because we define it doesn't mean Carol

is going to do it

we want karo to turn around so we call

the function so this is how we call the

function it tells karo to perform the

action and we can add more commands to

this karo can turn around then move

twice then turn left we can then call

turnaround function again now that Carol

knows the command we can do it as many

times as we want without having to

redefine the function we just need to

call it again so remember this is how we

teach Carol a new command and this is

how we get Carol to perform the command

keep in mind that in Python we need to

define the function before we can call

the function in other words the function

definition needs to appear higher in the

code compared to the call statement okay

so let's go to the editor and write our

own functions okay in this exercise

we're going to look at how we can teach

karo to turn around so our final

exercise that we want to end up we want

to end up with Carol facing the other

direction one space over so we can

basically teach Carol this new command

to turn around so remember to write a

function we start with a keyword def for

define and then we're going to write the

function turnaround so again our

function name starts with a letter

everything is lowercase and we give it

an action verb as our first word and

it's pretty descriptive we expect Cairo

to turn around when we use this function

okay so we give it a colon now remember

every command that we want to have

inside of this function has to be

indented one space over this the line

that we stopped indenting is the line

that is no longer part of our function

so turnaround is going to be really

simple it's just going to be a couple of

turn left commands we're gonna say turn

left turn left okay so now let's go look

if we go to run our code you'll notice

nothing actually happens so we've taught

Carol this command turnaround but we

haven't actually told Carol to do it yet

so let's go back and we can have Carol

move first and then we're gonna have

Carol turn around

okay and then we can maybe have Carol

move again and turn around again

now notice again I've defined the

function once I can call it as many

times as I want I don't need to redefine

it to call it a second time so if I

reset this and run here notice I turn

around call that function go back and I

go back up and I call that same function

again okay so I still didn't get to

exactly where I want to be so let me try

that again so I can do this again I can

move one more time and I can turn around

again I can use this code as many times

as I want without having to redefine it

up here's where I taught Carol how to

turn around and now here's where I

actually called in tell Carol to

actually do it I can do that as many

times as I want without having to

redefine it so let's go ahead and reset

and let's run that again so again it

goes back up to that function every time

it needs to use it but I don't have to

redefine it and there we go we've talked

Carol how to turn around now it's your

turn to play around