How to comment out a block of code in Python
PythonDocstringPython Problem Overview
Is there a mechanism to comment out large blocks of Python code?
Right now, the only ways I can see of commenting out code are to either start every line with a #, or to enclose the code in triple quotes: """.
The problem with these is that inserting # before every line is cumbersome and """ makes the string I want to use as a comment show up in generated documentation.
After reading all comments, the answer seems to be "No".
Python Solutions
Solution 1 - Python
Python does not have such a mechanism. Prepend a # to each line to block comment. For more information see PEP 8. Most Python IDEs support a mechanism to do the block-commenting-with-hash-signs automatically for you. For example, in IDLE on my machine, it's Alt+3 and Alt+4.
Don't use triple-quotes; as you discovered, this is for documentation strings not block comments, although it has a similar effect. If you're just commenting things out temporarily, this is fine as a temporary measure.
Solution 2 - Python
The only cure I know for this is a good editor. Sorry.
Solution 3 - Python
Hide the triple quotes in a context that won't be mistaken for a docstring, eg:
'''
...statements...
''' and None
or:
if False: '''
...statements...
'''
Solution 4 - Python
The only way you can do this without triple quotes is to add an:
if False:
And then indent all your code. Note that the code will still need to have proper syntax.
Many Python IDEs can add # for you on each selected line, and remove them when un-commenting too. Likewise, if you use vi or Emacs you can create a macro to do this for you for a block of code.
Solution 5 - Python
In JetBrains PyCharm on Mac use Command + / to comment/uncomment selected block of code. On Windows, use CTRL + /.
Solution 6 - Python
M-x comment-region, in Emacs' Python mode.
Solution 7 - Python
At least in VIM you can select the first column of text you want to insert using Block Visual mode (CTRL+V in non-windows VIMs) and then prepend a # before each line using this sequence:
I#<esc>
In Block Visual mode I moves to insert mode with the cursor before the block on its first line. The inserted text is copied before each line in the block.
Solution 8 - Python
In vi:
- Go to top of block and mark it with letter a.
- Go to bottom of block and mark it with letter b
Then do
:'a,'b s!^!#!
Solution 9 - Python
comm='''
Junk, or working code
that I need to comment.
'''
You can replace comm by a variable of your choice that is perhaps shorter, easy to touch-type, and you know does not (and will not) occur in your programs. Examples: xxx, oo, null, nil.
Solution 10 - Python
I use Notepad++ on a Windows machine, select your code, type CTRL-K. To uncomment you select code and press Ctrl + Shift + K.
Incidentally, Notepad++ works nicely as a Python editor. With auto-completion, code folding, syntax highlighting, and much more. And it's free as in speech and as in beer!
Solution 11 - Python
Yes, there is (depending on your editor). In PyDev (and in Aptana Studio with PyDev):
-
Ctrl + 4 - comment selected block
-
Ctrl + 5 - uncomment selected block
Solution 12 - Python
In Visual Studio using the Python Tools for Visual Studio, blocks can be commented out by Ctrl+K, Ctrl+C and uncommented by Ctrl+K, Ctrl+U.
Solution 13 - Python
In Eclipse + PyDev, Python block commenting is similar to Eclipse Java block commenting; select the lines you want to comment and use Ctrl + / to comment. To uncomment a commented block, do the same thing.
Solution 14 - Python
The only mechanism to comment out Python code (understood as code ignored by the interpreter) is the #.
As you say, you can also use string literals, that are not ignored by the interpreter, but can be completely irrelevant for the program execution.
Solution 15 - Python
Solution 16 - Python
Triple quotes are OK to me. You can use ''' foo ''' for docstrings and """ bar """ for comments or vice-versa to make the code more readable.
Solution 17 - Python
On Eric4 there is an easy way: select a block, type Ctrl+M to comment the whole block or Ctrl+alt+M to uncomment.
Solution 18 - Python
Another editor-based solution: text "rectangles" in Emacs.
Highlight the code you want to comment out, then C-x-r-t #
To un-comment the code: highlight, then C-x-r-k
I use this all-day, every day. (Assigned to hot-keys, of course.)
This and powerful regex search/replace is the reason I tolerate Emacs's other "eccentricities".
Solution 19 - Python
Use a nice editor like SciTe, select your code, press Ctrl + Q and done.
If you don't have an editor that supports block comments you can use a triple quoted string at the start and the end of your code block to 'effectively' comment it out. It is not the best practice though.