Comments are used to annotate, describe, or explain code that is complex or difficult to understand. The Python interpreter will intentionally ignore comments when it compiles to bytecode. PEP 8 has a section dealing with comments. They also increase the readablity of code by adding easy and descriptive language for better understanding.
Block and inline comments start with a # , followed by a space before the comment:
# This is a block comment.
print('Hello world!') # This is an inline commment.
Python does not include a formal way to write multiline comments. Instead, each line of a comment spanning multiple lines should start with # and a space:
# This is the first line of a multiline comment.
# This is the second line.
Alternatively you could use ''' to write a a comment that spans multiple lines to avoid having to use the # . For example:
'''
This is a multiline comment,
everything inside the three
apostrophes will be regarded
by Python as a comment and
ignored when running a program
'''
Another type of comment is the docstring , documented in PEP 257 . Docstrings are a specific type of comment that becomes the __doc__ attribute.
For a string literal to be a docstring, it must start and end with triple quotes """ and be the first statement of the module, function, class, or method definition it is documenting:
class SomeClass():
"""Summary line for SomeClass.
More elaborate descriptions may require using a
a multiline docstring.
"""
def method_a(self):
"""Single line summary of method_a."""
pass
String literals that start and end with """ that are not docstrings (not the first statement), can be used for multiline strings. They will not become __doc__ attributes. If they are not assigned to a variable, they will not generate bytecode. There is some discussion about using them as multiline comments found here.
Sample Code
def print_greeting(name):
"""This function will print a greeting to a friend."""
# prints the greeting with the name
print("Howdy, " + str(name) + "!")
print_greeting("John")
>>> Howdy, John!