All language subtitles for 002 Naming Conventions_en

In the last video, we talked about variables, what a variable is and how to declare a variable.

Now we'll go over naming conventions for variables.

Before starting, I'd like to talk a little bit about PEP, which stands for Python Enhancement Proposal,

and there are many of them.

A PIP is a document that describes new features proposed for Python and the documented aspects of Python

like design and style for the community.

For the moment, our focus is on PEP eight.

This is a document that provides guidelines and best practices on how to write Python code.

It was written in 2001 by Guido van Rossum, the author of Python and some other guys.

The primary focus of Pep eight is to improve the readability and consistency of Python code.

I recommend you to take a closer look at this document to see what its main points are.

This is really useful.

The recommendations I'll show you in this lecture.

Follow Pep eight.

In fact, I've tried to follow the guidelines provided by the document during the entire course, as

well as at my daily job when I code.

Let's move on and see some rules about naming variables.

Variable names can contain letters, digits and underscore.

For example, my underline name equals Andre age equals 40.

And they underline one equals, let's say today are all valid and recommended variable names.

A variable name can start with the number.

It can only start with an underscore or a letter.

For example, for you equals.

Thank you.

Is not a valid variable name.

This is an error.

This is not permitted in Python.

Pay attention if it starts with an underscore or double underscores, it has a special meaning to Python

and you should avoid it.

For example, underscore bonus equals 100 is a variable name but has special meaning to python and should

be avoided.

Don't use special characters in variable names like spaces, exclamation or question marks, parentheses

and so on.

For example, a exclamation mark equals eight is not permitted or a dot B equals 100.

They are not permitted.

Variable names can't be reserved words like true false non class if.

Else while.

And so on.

For example y equals ten is a syntax error while.

Is the language keyword.

It's recommended to use works written with lowercase letters separated by underscores.

Like for example, max underlined value equals 99.

By the way, this is known as Snake Case.

This is different from the camel case notation recommended in other programming languages, for example,

in Java.

The camel case notation means two group works by writing each word in the middle of the phrase with

no intervening spaces or punctuation.

For example, max permitted value equals 100.

This is camel case.

Using the camel case notation is not an error, but is not recommended.

Avoid using words that have special meanings or are already defined as data types like list, str,

set, tuple, and so on.

For example, SDR equals Python is not recommended.

There is no error.

But is not recommended.

Python is case sensitive.

It makes a distinction between lower and uppercase letters, and so are variable names.

A equals eight and the capital A equals ABC are two different variables.

Of course, you don't have to follow these conventions Exactly.

As long as you try to remain consistent within your own code.

So up next, you are going to have a quick quiz just to make sure that you have deeply understood everything

about the variables.

Good luck with the quiz and I'll see you in the next video where we'll talk about comments in Python.