python examples

Small examples of Python code, data structures and algorithms.

Python naming conventions

Public elements

Type	Notation	Example	Notes
Class	PascalCase (UpperCamelCase)	MyClass
Constant	SCREAMING_SNAKE_CASE	MY_CONSTANT	Uppercase single letter, word, or words. Separate words with underscores.
Enum values	SCREAMING_SNAKE_CASE	SOME_ENUM
Exception	PascalCase (UpperCamelCase)	MyException
Function/Method	snake_case	my_function()	Lowercase word or words. Separate words by underscores.
Module	snake_case	my_module.py	Short. Lowercase word or words. Underscores can be used if improves readability.
Package	lowercase	mypackage	Short. Lowercase word or words. The use of underscores is discouraged.
Variable	snake_case	my_variable	Lowercase single letter, word, or words. Separate words with underscores.

Private elements

No attribute is really private in Python (without a generally unnecessary amount of work), but there are conventions:

Convention	Meaning	Use
_single_leading_underscore	Weak internal use indicator.	The object is meant to be private, and shouldn't be directly accessed from outside the class.
__double_leading_underscore	Invokes name mangling.	A way to make instance variables less likely to collide with variables in subclasses.

Comments

• Should be complete sentences. The first word should be capitalized, unless it is an identifier that begins with a lower case letter.
• Block comments generally consist of one or more paragraphs built out of complete sentences, with each sentence ending in a period.
• Use two spaces after a sentence-ending period in multi-sentence comments except after the final sentence.

  • Block Comments

    Block comments generally apply to some (or all) code that follows them, and are indented to the same level as that code. Each line of a block comment starts with a # and a single space (unless it is indented text inside the comment).
    Paragraphs inside a block comment are separated by a line containing a single #.

    # Use this function to check code quality. 
    # Code quality is defined by the following parameters: 
    # - The code follows naming conventions
    # - The code is easy to understand
    # - ...
    def check_code_quality(code):
      ...

  • Inline Comments

    Inline comments should be separated by at least two spaces from the statement. They should start with a # and a single space.

    if len(commits) > 0:  # Make sure that there is commits
      ...

Documentation strings

• Write docstrings for all public modules, functions, classes, and methods. A docstring is the first statement in a package, module, class or function. Docstrings are not necessary for non-public methods, but you should have a comment that describes what the method does.

  • The """ that ends a multiline docstring should be on a line by itself.

    def draw_circle():
        """
        Returns a circle
        Draws a circle.
        """
        ...

• For one-liner docstrings keep the closing """ on the same line:

  """Returns a circle."""

Python file format

1. Hashbang
2. Docstrings
3. Imports
4. Code

Sources

• PEP 8
• Google Python Style Guide

Support

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