Question

While reviewing some code used in the online CS188.1x class on edX.org (code written by the instructors), I noticed the repeated use of a single set of double quotes (like one might use around a str) for use as comments.

I haven’t seen this before, nor is it mentioned in PEP8 that I could find, but it certainly seems to work fine. Can anyone enlighten me?

Here’s an example:

class SomeClass():
    """
    Some docstring info, using standard 'triple double quotes'
    """
    def  __init__(self):
        "This is the comment style to which I'm referring."
        some.code = foo      # Here's a normal inline comment

    def bar(self, item):
        "Here is another example of the comment style"
       return wtf

Answer 1

A docstring is any string literal that appears as the first statement in a class, method, function or module. Stylistically it’s typical and preferred to use the triple quote format to allow for longer, better formatted docstrings, and to call attention to them for easy reference, but any string will qualify.

Docstrings are distinct from comments because comments are not relevant to the execution of a program at all, whereas docstrings are available at runtime by accessing an object’s __doc__ variable.