How to comment out a block of code in Python [dupl

问题:

This question already has an answer here:

• Why doesn't Python have multiline comments? 16 answers

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".

回答1:

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-pound-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.

回答2:

The only cure I know for this is a good editor. Sorry.

回答3:

Hide the triple quotes in a context that won't be mistaken for a docstring, eg:

'''
...statements...
''' and None

or:

if False: '''
...statements...
'''

回答4:

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.

回答5:

M-x comment-region, in Emacs' Python mode.

回答6:

In JetBrains PyCharm on Mac use Command + / to comment/uncomment selected block of code. On Windows, use CTRL + /.

回答7:

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.

回答8:

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!^!#!

回答9:

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

回答10:

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.

回答11:

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.

回答12:

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.

回答13:

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!

回答14:

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.

回答15:

In Eclipse using PyDev, you can select a code block and press Ctrl + #.

回答16:

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".

回答17:

On Eric4 there is an easy way: select a block, type Ctrl+M to comment the whole block or Ctrl+alt+M to uncomment.

回答18:

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.

回答19:

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.