The One Character Block Comment

http://www.vancelucas.com/blog/the-one-character-block-comment/

by vlucas • 17 years ago

44 37 17 years ago

skip• 17 years ago

It's a nice trick, but I will probably stick to Ctrl-K-C (block comment) and Ctrl-K-U (block uncomment) in Visual Studio, just out of habit. I hate leaving big block comments in the middle of a module anyways: hurts readability.

jasonkester2• 17 years ago

It's probably telling that his code sample is PHP. Though I seem to remember Eclipse having support for CTRL+/ style block commenting/uncommenting. Most other good IDEs (and emacs, as noted below) do it too.

But yeah, I sometimes take for granted how nice VS.NET is at these little detail things (though I use resharper-style CTRL+/ bindings for this particular feature). Thanks to this author and his pain for reminding me how good we have it.

latortuga• 17 years ago

Not to mention TextMate, e (the windows textmate clone) and vi...I feel like this is a pretty basic text editor feature, for programmers at least.

mixmax3• 17 years ago

It's probably telling that his code sample is PHP

Excuse me, but last time I checked PHP was one of the most widely deployed languages in the world, which a lot of people smarter than you and I spend their working time hacking. Can we please stop the PHP bashing.

rwolf• 17 years ago

For the gedit kids feeling left out in the audience, check out the plugin "code comment". Who loves you, baby?

jackdawjack• 17 years ago

uuh surely most editors can do this for you? m-x comment-region in emacs for instance

wmeredith• 17 years ago

I think the point of this is it's application agnostic.

shimon• 17 years ago

Emacs users: try the comment-dwim command, usually bound to M-;. This will toggle the commented-ness of the selected code and be relatively smart about it. "dwim" stands for "do what I mean". :)

jf• 17 years ago

Yes! And for the times when you are in a mode that comment-dwim doesn't know the comment syntax for, you can use the string-rectangle (C-x r t) command to comment regions.

jseifer• 17 years ago

It's usually command / in TextMate.

huhtenberg• 17 years ago

Anyone who discovered, went bananas for and then eventually stopped using this trick on their own, raise your hand.

jcromartie• 17 years ago

In C I don't use block comments, I just use:

    #if 0
      ...
    #endif

One character, no comment syntax hacks.

thunk• 17 years ago

I find it really helpful to have a duplicate-and-comment-block command, so you can immediately start hacking on an uncommented dup. Used with another command to dump blocks to a junk file, it's like a wee block-level SCM.

Periodic• 17 years ago

This is a pattern I tend to use as well because it lets you reference known working code when changing things, and easily switch between development and stable code. However, usually it's just one line, so "copy, paste, comment, move" works well enough.

waldrews• 17 years ago

Please please don't do this. It hurts readability, and relies on a subtle grammar ambiguity. Without a highlighting editor (e.g. reading a diff in a code review) I'll be scratching my head trying to read this. And tools like editors that have an imperfect parser are likely to get confused.

There's a chance you'll confuse yourself (or your code reviewer or other reader) and spend an hour debugging to find what you thought was commented out wasn't. That's not worth it to save one keystroke.

Mintz• 17 years ago

I think the purpose the author shared this technique for is when you need to constantly comment/uncomment a block of code for testing.

I agree with you, though. Once you're done with your experiment, reset the commented lines to something more conventional.

moe3• 17 years ago

Even then, any editor worth its salt supports comment toggling with a single keystroke anyways. Good editors (vim, cough) can even toggle lines or paragraphs regardless of cursor position.

So I agree, this hack is more trouble than its worth.

mjgoins• 17 years ago

Oh if I could upvote this comment more times I would.

The example code here made me immediately think of the lines of code that caused the Debian SSL catastrophe.

nollidge• 17 years ago

He keeps saying "backslash" when it's a forward-slash (or just "slash").

pbhjpbhj2• 17 years ago

Suppose it depends on whether your normal language is rtl or ltr?

akronim• 17 years ago

> this trick will work with any language that supports both single-line and block style comments

isn't this just a horrible workaround for not having a debugger?

nimbix• 17 years ago

Or, you could use an editor more advanced than notepad.exe and use a "toggle comment" command which which allows you to switch between

  //line 1
  //line 2
  //...
  //line N

...and...

  line 1
  line 2
  ...
  line N

...with more flexibility than using a syntax trick.

dfranke2• 17 years ago

This is also an old trick to test whether your code was compiled as a C++ or not:

  2//**/2
    == 1) ? "C" : "C++"

timf• 17 years ago

Is there a situation where you would need this instead of "#ifdef __cplusplus"?

e.g. http://www.parashift.com/c++-faq-lite/mixing-c-and-cpp.html#...

dfranke2• 17 years ago

No. It's just for hack value.

yason• 17 years ago

This is fun and has some hack value but I hope nobody ever uses such a kludge in real code.

It totally fails with crappy C compilers that decide to feature C++ comments unannounced. IIRC gcc does this unless you give -ansi or -std=c89. And C99 officially supports the // -comments but hasn't got C++ features, of course.

jff• 17 years ago

The real solution is to make your code work properly every time.

Or, in Plan 9's acme editor, we just highlight the desired text and execute the following command in the tag area: Edit s/^/\/\//g

Then when we're ready to go back, we just select again and do: Edit s/^\/\///g which is the same as the previous command but with one forward slash moved.

Alternately, in almost every case it's easy enough to just stick in /* */ comments around it and delete them as necessary.

bodhi• 17 years ago

Seems to be a lot of hate on this trick here. One difference between this trick and "I just press <shortcut key> in my IDE" is that this will comment out one block of code, but will also uncomment a second block at the same time.

vlucas• 17 years ago

I must say I didn't expect so much hate for this comment hack. Hack? That's right, it absolutely is a hack - and it's definitely not the most elegant solution.

I think a lot of people really missed the point here, and used comments as a way to flaunt their clearly more impressive and infinitely superior geek prowess by using IDEs and emacs.

The point was to present a solution that was fairly platform and language agnostic. If I had included an IDE shortcut in the article, I would have had to go through a long list of all the IDEs out there and all their corresponding shortcuts. I would have then been inevitably flamed for missing some or for not representing a specific programming language.

Oh, and don't forget to bash PHP or point out how much I suck at programming for using PHP. Because everyone knows only cool developers and true geeks don't use PHP.

The One Character Block Comment

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