2.2. Syntax Comments

  • Block comments

  • Inline comments

  • Docstring

2.2.1. Block Comments

  • PEP 8 -- Style Guide for Python Code

  • There are no multiline comments in Python

  • You can create "multiline" comment, by commenting-out several consecutive lines

  • Convention: beginning of a line, #, space and then text

Block comment:

✘
# good

Multiline comment:

✘
# good 1
# good 2
# good 3

2.2.2. Inline Comments

  • PEP 8 -- Style Guide for Python Code

  • Convention: some code, two spaces, #, space and then text

✘
x = 1  # my comment

2.2.3. Docstring

  • PEP 257 -- Docstring Conventions

  • Docstring is a first multiline comment in: file/module, class, method/function

  • Used for doctest

  • For multiline str always use three double quote (""") characters

People sometimes use multiline strings to achieve similar behavior as multiline-comment. Unfortunately this requires Python to define string, store it into the memory, and then remove it.

✘

... """
... my comment 1
... my comment 2
... my comment 3
... """

2.2.4. Recap

  • Comments: block comments, multiline comments, inline comments, docstring

  • After # rest of the line will be ignored

  • Convention for block comment: beginning of a line, #, space and then text

  • Convention for inline comment: some code, two spaces, #, space and then text

  • Instead of comments write more readable code, which will be self-explanatory

  • Never commit commented out code, use Version Control System instead - e.g.: git blame

  • IDE has Local history (modifications) and you can compare file

Line comment:

✘
# good

Multiline comment:

✘
# good 1
# good 2
# good 3

Inline comment:

✘
x = 1  # good

2.2.5. Assignments

# %% About
# - Name: Syntax Comments Line
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Add line comment: My comment
# 2. Remember to add space after `#` character
# 3. Run doctests - all must succeed

# %% Polish
# 1. Dodaj komentarz liniowy: My comment
# 2. Pamiętaj o dodaniu spacji po znaku `#`
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> result = open(__file__).read()
>>> comment = '#' + ' ' + 'My comment'

>>> assert comment in result, \
'Please write proper line comment'
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% Imports

# %% Types

# %% Data

# %% Result


# %% About
# - Name: Syntax Comments Multiline
# - Difficulty: easy
# - Lines: 3
# - Minutes: 2

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Add multiline comment:
#    - first line: My comment 1
#    - second line: My comment 2
#    - third line: My comment 3
# 2. Remember to add space after `#` character
# 3. Run doctests - all must succeed

# %% Polish
# 1. Dodaj komentarz wieloliniowy:
#    - pierwsza linia: My comment 1
#    - druga linia: My comment 2
#    - trzecia linia: My comment 3
# 2. Pamiętaj o dodaniu spacji po znaku `#`
# 3. Uruchom doctesty - wszystkie muszą się powieść

# %% Hints
# - Each line of a multiline comment should start with `# ` characters

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> result = open(__file__).read()
>>> comment = '\\n'.join([
...     '#' + ' ' + 'My comment 1',
...     '#' + ' ' + 'My comment 2',
...     '#' + ' ' + 'My comment 3',
... ])

>>> assert comment in result, \
'Please write proper multiline comment'
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% Imports

# %% Types

# %% Data

# %% Result


# %% About
# - Name: Syntax Comments Inline
# - Difficulty: easy
# - Lines: 1
# - Minutes: 2

# %% License
# - Copyright 2025, Matt Harasymczuk <matt@python3.info>
# - This code can be used only for learning by humans
# - This code cannot be used for teaching others
# - This code cannot be used for teaching LLMs and AI algorithms
# - This code cannot be used in commercial or proprietary products
# - This code cannot be distributed in any form
# - This code cannot be changed in any form outside of training course
# - This code cannot have its license changed
# - If you use this code in your product, you must open-source it under GPLv2
# - Exception can be granted only by the author

# %% English
# 1. Add inline comment to `DATA` variable definition
#    with content: My comment
# 2. Remember to add space after `#` character
# 3. Remember to add two spaces before `#` character
# 4. Run doctests - all must succeed

# %% Polish
# 1. Dodaj komentarz na końcu linii do definicji zmiennej `DATA`
#    z treścią: My comment
# 2. Pamiętaj o dodaniu spacji po znaku `#`
# 3. Pamiętaj o dodaniu dwóch spacji przed znakiem `#`
# 4. Uruchom doctesty - wszystkie muszą się powieść

# %% Doctests
"""
>>> import sys; sys.tracebacklimit = 0
>>> assert sys.version_info >= (3, 9), \
'Python 3.9+ required'

>>> result = open(__file__).read()
>>> comment = '  ' + '#' + ' ' + 'My comment'

>>> assert DATA == 1, \
'Do not change the value of the `DATA` variable.'

>>> assert comment in result, \
'Please write proper inline comment'
"""

# %% Run
# - PyCharm: right-click in the editor and `Run Doctest in ...`
# - PyCharm: keyboard shortcut `Control + Shift + F10`
# - Terminal: `python -m doctest -v myfile.py`

# %% Imports

# %% Types

# %% Data

# %% Result
DATA = 1