Karel Python - Commenting Code

Summary

This video script emphasizes the importance of code commenting for readability and maintainability. It distinguishes between multi-line and single-line comments, illustrating how to use them effectively. The script advocates for the inclusion of preconditions and postconditions in function comments to enhance understanding. It provides an example using a 'Carol' program, demonstrating how to document program functionality and function behavior, encouraging viewers to practice commenting in their code.

Takeaways

• 😀 Code commenting is essential for good programming style, making the code readable and understandable to others.
• 🔍 The dual importance of functionality and style in programming: the program must work and be clear to others.
• 📝 Comments serve as notes in plain English to explain what the code is doing, aiding in understanding by both the original coder and others.
• 👥 Comments are crucial for collaborative coding environments, as they help team members understand each other's code.
• 📖 There are two types of comments: multi-line comments, enclosed by triple double quotes, and single-line comments, started with a hashtag.
• ✂️ Multi-line comments are used for longer explanations and are ignored by the computer until the closing triple double quotes.
• ✏️ Single-line comments are used for brief notes and are ignored from the hashtag to the end of the line.
• 🔑 Precondition and postcondition are key elements to include in function comments, explaining the state before and after the function is called.
• 🛠️ Good commenting practice involves defining what the program does at the start with a multi-line comment and detailing functions with preconditions and postconditions.
• 🎯 Use comments to guide the reader through the logic and purpose of the code, enhancing maintainability and readability.
• 💡 Encourage experimentation with commenting to improve coding style and ensure that code remains understandable over time.

Q & A

What are the two main aspects of writing a program according to the video?

The two main aspects of writing a program are functionality, which determines if the program works and does what it's supposed to, and style, which assesses if the program is clear, readable, and makes sense to others.

Why is it important to have good style in code?

Good style in code is important because it makes the program clear to others, ensuring that the code can be read and understood by other programmers, which is crucial for collaboration and maintenance over time.

What role do comments play in writing programs with good style?

Comments play a crucial role in writing programs with good style as they allow programmers to leave notes about what the code is doing in plain English, aiding in understanding and collaboration among team members.

What are the two types of comments mentioned in the video?

The two types of comments mentioned in the video are multi-line comments, which are enclosed by three double quotes, and single-line comments, which start with a hashtag.

How does a multi-line comment start and end in the video's context?

A multi-line comment starts with three double quotes and ends with another set of three double quotes. Everything between the two sets is ignored by the computer.

What is the purpose of a single-line comment in code?

A single-line comment is used to ignore a specific line of code from being executed by the computer. It starts with a hashtag and the comment ends automatically at the end of the line.

What should be included in comments according to the video?

According to the video, comments should include preconditions and postconditions of a function, which are the assumptions made before the function is called and what should be true after the function is called, respectively.

Can you provide an example of a precondition and postcondition mentioned in the video?

An example of a precondition mentioned in the video is that Carol has jumped the last hurdle and is facing east before the 'run to finish' function is called. The postcondition is that Carol has reached the finish line after the function execution.

How does commenting help in a team setting?

Commenting helps in a team setting by providing clarity on the code's purpose and functionality, assisting team members in understanding the code's intent and logic without needing to decipher the code itself.

What is the significance of commenting on the long-term maintainability of code?

Commenting is significant for long-term maintainability of code as it allows future developers, including the original programmer, to quickly grasp the code's purpose and functionality, facilitating easier updates and debugging.

How does the video suggest documenting the program's purpose and functions?

The video suggests using multi-line comments for documenting the program's purpose by explaining what the program does, and using both multi-line and single-line comments to document functions, including their preconditions and postconditions.

Outlines

00:00

📝 Importance of Code Commenting

The first paragraph emphasizes the significance of not only making a program functional but also ensuring it has a good style, which includes writing clear and readable code for others to understand. It introduces the concept of comments as a means to leave notes about the code's purpose in plain English, highlighting the importance of comments in collaborative coding environments. It also differentiates between two types of comments: multi-line comments, which use triple double quotes, and single-line comments, which start with a hashtag.

🗨️ Types of Comments in Programming

This paragraph delves into the specifics of how to comment in code, explaining the syntax for creating multi-line comments using triple double quotes and single-line comments using hashtags. It clarifies that the computer ignores everything within the triple double quotes and anything following a hashtag on the same line. The paragraph also touches on the content that should be included in comments, such as preconditions and postconditions of functions, which are essential for understanding the assumptions and expected outcomes of the code.

🛠️ Demonstrating Comments in a Sample Program

The final paragraph provides a practical example of how to apply comments in a coding environment, using a program named 'Carol' as a reference. It illustrates the use of multi-line comments to describe the overall purpose of the program and single-line comments to explain specific actions within the code. The paragraph also discusses the importance of documenting preconditions and postconditions for functions, giving a concrete example of how to comment on a function that makes Carol run to the finish line after jumping hurdles.

Keywords

💡Commenting

Commenting refers to the practice of adding notes or explanations within a codebase to clarify the purpose and functionality of the code. In the video, commenting is presented as a crucial aspect of programming style, essential for making code readable and understandable by others. Examples from the script include using comments to explain preconditions and postconditions of functions.

💡Programming Style

Programming style encompasses the conventions and practices that make code clear, readable, and maintainable. The video emphasizes that good style is not just about functionality but also about how the code is organized and presented, making it accessible to other programmers. The script discusses the importance of breaking down problems and using comments to enhance style.

💡Functionality

Functionality in programming refers to the working aspects of a program, ensuring it performs its intended tasks. The video script mentions that while functionality is important, it is equally important to have good style, indicating that a program must not only work but also be well-structured and commented for others to understand.

💡Code Readability

Code readability is the ease with which a reader can understand the code. The video stresses the importance of writing code that is clear to others, which is achieved through good programming style and the use of comments. The script provides examples of how comments can improve readability by explaining what the code is intended to do.

💡Preconditions

Preconditions are the conditions or assumptions that must be true before a function is executed. In the context of the video, preconditions are highlighted as an important aspect to document in comments, ensuring that the state or requirements needed for the function to work correctly are clear. The script uses the example of Carol's state before running to the finish line as a precondition.

💡Postconditions

Postconditions define the expected state or results after a function has executed. The video explains that documenting postconditions in comments is vital for understanding what the function will achieve. The script illustrates this with the example of Carol reaching the finish line after running, which is the postcondition of the function.

💡Multi-line Comments

Multi-line comments are used to span multiple lines of text within a code, typically enclosed by a specific syntax that indicates the start and end of the comment block. The video script demonstrates how to create multi-line comments using three double quotes, which allows for extended explanations that are ignored by the computer but provide clarity to human readers.

💡Single-line Comments

Single-line comments are used to add a brief note or explanation on a single line of code, starting with a specific character (e.g., '#') that signals the beginning of the comment. The video script explains that once the computer encounters this character, it ignores the rest of the line, and the comment ends automatically at the end of the line.

💡Teams and Groups

Teams and groups refer to the collaborative nature of coding, where multiple programmers often work together on the same project. The video script mentions that comments are essential in such environments because they help team members understand each other's code, facilitating collaboration and code maintenance.

💡Carol

In the context of the video script, 'Carol' is a character or a variable representing an entity within the program being discussed. The script uses Carol as an example to illustrate how comments can describe actions and states, such as Carol starting at the bottom, jumping hurdles, and running to the finish line.

Highlights

The video emphasizes the importance of code commenting for style and readability.

Code functionality and style are both essential components of programming.

Well-commented code is crucial for understanding and maintenance by others.

Comments serve as notes in plain English explaining what the code is doing.

Coding is often a collaborative effort, necessitating clear communication through comments.

There are two types of comments: multi-line and single-line.

Multi-line comments are created using three double quotes and can span multiple lines.

Single-line comments use the hashtag and are ignored after the hashtag until the end of the line.

Preconditions and postconditions of a function should be described in comments.

Preconditions are assumptions that must be true before a function is called.

Postconditions define the expected state after the function execution.

Demonstration of commenting in an editor with a sample program about Carol.

The program description is provided within multi-line comments for clarity.

Function definitions include preconditions and postconditions for better understanding.

An example of a single-line comment explaining a specific action in the code.

The video encourages viewers to practice commenting in their own code.

The video concludes by inviting viewers to explore and experiment with commenting.

Transcripts

hi in this video we're gonna look at

commenting your code so you've got to

have good style there are two parts to

writing a program functionality does it

work does it do what it's supposed to

there's also a style component is your

program clear and readable and does it

make sense to others it's not enough for

your program to work it also has to have

good style a good style means that

you've broken down the problem in a

reasonable way and your code is clear to

others it's a very important part of

programming and we want to be able to

write readable code code that others can

read and understand for years to come an

important part of writing programs with

good style is comments so introducing

comments comments are a way for you to

leave notes about what your code is

doing in plain English so why comment

although code is run by computers it's

read by other people coding is not a

solo exercise coding is usually done in

teams in groups so comments help others

and you understand what your code is

trying to do so how do we comment there

are two different types of comments

multi-line comments and single line

comments so create a multi-line comment

we use three double quotes then leave

comments on the next lines to end a

multi-line comment we use another set of

three double quotes everything between

the two sets of three double quotes is

ignored by the computer we can also do

single line comments these are done by

using hashtags on any line once the

computer sees the hashtag it'll ignore

the remainder of that line of code but

start reading automatically on the next

line notice that a single line comment

doesn't have anything to end the comment

the comment just ends automatically at

the end of the line so what exactly do

we communicate in a comment one of the

most important things we can comment

about are the preconditions and

postconditions of a function

preconditions are the assumptions that

we make and what must be true before the

function is called the post conditions

are what should be true after the

function is called so for all of our

functions we should write preconditions

and post

conditions so let's take a look at some

comments in the editor okay so let's

take a look at comments in Carol so

we're gonna start off by commenting this

her dota Carol the first thing we want

to do is kind of define what our program

is talking about so we're going to put

in our two sets of triple double quotes

and then kind of talk about what the

program does we're gonna say this

program has Carol start bottom and jump

two hurdles before running to the finish

okay so something like that it tells us

exactly what this programs supposed to

do okay then we can define our functions

so again we'll use two sets of triple

double quotes okay

and so this run to finish we'll say this

function as Carol run to the finish line

after jumping the last hurdle now what

we want to do with functions is we want

to have our precondition in a post

condition so I'm going to say

precondition is and that is precone the

precondition is what condition Carol

will be in at the start is we're going

to say Carol has jumped the last hurdle

and is facing east okay and the post

condition tells us exactly what

condition Carol is going to be in at the

end of the function so we're gonna say

Carol has reached the finish line okay

and we can go ahead and do the same

thing for these others I'm gonna leave

those for you right

now but what I want to do is just show

you how we can do a single line comment

so again if we do a single line comment

we just start with a hashtag and we can

say this program will have Carol jump

have Carol jump two hurdles so again we

can do single line comments like that we

can do multi-line comments like that you

can see the rest of the comments in the

examples and now it's time for you to

play around