Comments are essential to make the code readable and understandable for other developers who may be working on the same project, or for yourself when you come back to your code after a long period of time. In Python, comments are indicated by the “#” symbol at the beginning of a line.
In Python, there are two types of comments: single-line comments and multi-line comments. Single-line comments start with a “#” symbol, and everything following it on that line is ignored by the interpreter. For example:
# This is a single-line comment x = 5 # This is also a single-line comment
Multi-line comments, also known as docstrings, are used to comment on larger blocks of code or to provide documentation for a function or module. They are enclosed in triple quotes (“””). For example:
""" This is a multi-line comment, also known as a docstring """ def my_function(): """ This is a docstring for the my_function() function """
It’s also possible to use multi-line comments to comment out multiple lines of code at once.
""" x = 5 y = 6 z = 7 """
It’s worth noting that Python does not have a traditional multiline comment syntax, using triple quotes for multi-line strings, which also serves as a multi-line comment
Tips for effectively commenting code in Python
- Be clear and concise: Comments should be clear and concise, and should explain what the code is doing, not how it’s doing it. Avoid jargon or technical terms that may not be understood by all readers.
- Comment why, not how: Comments should explain why the code is written in a certain way, rather than how it works. It’s important to understand that the code itself should be self-explanatory.
- Use meaningful variable names: Using meaningful variable names can make your code more self-explanatory and reduce the need for comments.
- Comment complex or non-obvious code: Comment complex or non-obvious code to make it easier to understand.
- Use docstrings for functions and modules: Use docstrings to provide documentation for functions and modules. Docstrings should explain what the function or module does, its arguments, and its return value.
- Keep comments up-to-date: Comments should be kept up-to-date with the code. If the code changes, the comments should be updated accordingly.
- Use consistent formatting: Comments should be formatted consistently throughout the code. For example, always use the same indentation for comments, or always start comments with a capital letter.
- Avoid commenting out code: Instead of commenting out code, use version control to track changes in the code. This allows for easy retrieval of old code if needed, and also makes it clear that the code is no longer in use.