Functions in Karel - Python
Summary
TLDRThis 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
📘 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.
🔄 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.
Mindmap
Keywords
💡functions
💡problem-solving
💡code readability
💡programming languages
💡def keyword
💡function naming
💡snake case
💡action verb
💡function definition
💡function call
💡indentation
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
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