Style guidelines for identifiers (Python 3)

Style guidelines for identifiers

A good practice when naming variables is to use all lowercase letters and to place underscores between words. This lowercase and underscore convention for naming variables originates from the Python style guide, PEP 8. PEP 8 (PEP is an acronym for Python Enhancement Proposal) is a document that outlines the basics of how to write Python code neatly and consistently. Code is read more often than written, so having a consistent variable naming scheme helps to ensure that programmers can understand each other's code.

Programmers should create meaningful names that describe an item's purpose. If a variable will store a person's age, then a name like "age" is better than "a". A good practice when dealing with scientific or engineering names is to append the unit of measure, for example, instead of temperature, use temperature_celsius. Abbreviations should only be used if widely understandable, as in tv_model or ios_app. While meaningful names are important, very long variable names, such as "average_age_of_a_UCLA_graduate_student," can make subsequent statements too long and thus hard to read, so programmers find a balance between meaningful names and short names. Below are some examples of names that perhaps are less meaningful and more meaningful.

Table 2.2.1: Use meaningful variable names.

Purpose	Less meaningful names	More meaningful names
The number of students attending UCLA	ucla num nu	num_students_ucla qty_ucla_student_body_pop
The size of a television set measured as its diagonal length	sz_tv size	diagonal_tv_size_inches
The word for the ratio of a circle's circumference/diameter	p	pi
The number of jelly beans in a jar, as guessed by a user	guess num njb	num_guessed_jelly_beans user_guess_jelly_beans

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A list of reserved keywords in the language are shown below:

Table 2.2.2: Python 3 reserved keywords.

False await else import pass None break except in raise True class finally is return and continue for lambda try as def from nonlocal while assert del global not with async elif if or yield

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Source: http://docs.python.org/3/reference/lexical_analysis.html