Interactively, you can display it with:
help(my_func)
Or from code you can retrieve it with (surround it with print(.) to get a formatted output):
my_func.__doc__
Advice on writing some docstrings
python - Getting the docstring from a function - Stack Overflow
coding style - What are the most common Python docstring formats? - Stack Overflow
Propper way to write DocStrings
Videos
I need to write docstrings for every method and property in this file:
https://github.com/golemfactory/yapapi/blob/master/yapapi/services/service_runner.py
A couple questions.
Should you write a docstring for an init method? I suppose it depends? This one seems self explanatory. Should I just state what the code does? “ServiceRunner class is initialized with four parameters: job, instance, instance_tasks, and stopped.”
I could explain what each of those do. I actually have some questions about them. “Job” is clearly passed the string “job”, so I don’t understand the later call “job.id” - the string returns an ID?
As for: self._instances: List[Service] = [] - how can you pass an entire statement as an attribute? They convert “Service” to a list but then assign it as an empty list… will the result be the list of services or the empty list?
Just that for now. Please let me know if you understand this a bit better than I do.
Thanks very much
Interactively, you can display it with:
help(my_func)
Or from code you can retrieve it with (surround it with print(.) to get a formatted output):
my_func.__doc__
You can also use inspect.getdoc. It cleans up the __doc__ by normalizing tabs to spaces and left shifting the doc body to remove common leading spaces.
Formats
Python docstrings can be written following several formats as the other posts showed. However the default Sphinx docstring format was not mentioned and is based on reStructuredText (reST). You can get some information about the main formats in this blog post.
Note that the reST is recommended by the PEP 287
There follows the main used formats for docstrings.
- Epytext
Historically a javadoc like style was prevalent, so it was taken as a base for Epydoc (with the called Epytext format) to generate documentation.
Example:
"""
This is a javadoc style.
@param param1: this is a first param
@param param2: this is a second param
@return: this is a description of what is returned
@raise keyError: raises an exception
"""
- reST
Nowadays, the probably more prevalent format is the reStructuredText (reST) format that is used by Sphinx to generate documentation. Note: it is used by default in JetBrains PyCharm (type triple quotes after defining a method and hit enter). It is also used by default as output format in Pyment.
Example:
"""
This is a reST style.
:param param1: this is a first param
:param param2: this is a second param
:returns: this is a description of what is returned
:raises keyError: raises an exception
"""
Google has their own format that is often used. It also can be interpreted by Sphinx (ie. using Napoleon plugin).
Example:
"""
This is an example of Google style.
Args:
param1: This is the first param.
param2: This is a second param.
Returns:
This is a description of what is returned.
Raises:
KeyError: Raises an exception.
"""
Even more examples
- Numpydoc
Note that Numpy recommend to follow their own numpydoc based on Google format and usable by Sphinx.
"""
My numpydoc description of a kind
of very exhautive numpydoc format docstring.
Parameters
----------
first : array_like
the 1st param name `first`
second :
the 2nd param
third : {'value', 'other'}, optional
the 3rd param, by default 'value'
Returns
-------
string
a value in a string
Raises
------
KeyError
when a key error
OtherError
when an other error
"""
Converting/Generating
It is possible to use a tool like Pyment to automatically generate docstrings to a Python project not yet documented, or to convert existing docstrings (can be mixing several formats) from a format to an other one.
Note: The examples are taken from the Pyment documentation
The Google style guide contains an excellent Python style guide. It includes conventions for readable docstring syntax that offers better guidance than PEP-257. For example:
def square_root(n):
"""Calculate the square root of a number.
Args:
n: the number to get the square root of.
Returns:
the square root of n.
Raises:
TypeError: if n is not a number.
ValueError: if n is negative.
"""
pass
I like to extend this to also include type information in the arguments, as described in this Sphinx documentation tutorial. For example:
def add_value(self, value):
"""Add a new value.
Args:
value (str): the value to add.
"""
pass