Page 55 - Python Basics: A Practical Introduction to Python 3

3.3. Create a Variable

seconds is a better name than s because it provides more context. But
it still doesn’t convey the full meaning of the code. Is 3600 the number
of seconds it takes for a process to finish, or is it the length of a movie?
There’s no way to tell.

The following name leaves no doubt about what the code means:

seconds_per_hour = 3600

When you read the above code, there’s no question that 3600 is the
number of seconds in an hour. seconds_per_hour takes longer to type
than both the single letter s and the word seconds, but the payoff in
clarity is massive.

Although naming variables descriptively means using longer variable
names, you should avoid using excessively long names. A good rule
of thumb is to limit variable names to three or four words maximum.

Python Variable Naming Conventions

In many programming languages, it’s common to write variable
names in mixedCase. In this system, you capitalize the first letter
of every word except the first and leave all other letters in lowercase.
For example, numStudents and listOfNames are written in mixedCase.

In Python, however, it’s more common to write variable names in
lower_case_with_underscores. In this system, you leave every
letter in lowercase and separate each word with an underscore. For
instance, both num_students and list_of_names are written using the
lower_case_with_underscores system.

There’s no rule mandating that you write your variable names in
lower_case_with_underscores. The practice is codified, though, in a
document called PEP 8, which is widely regarded as the official style
guide for writing Python.

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