The comment reply system is, at first glance, a fairly elegant and simple system that solves a fundamental problem with comments. However, there are many pitfalls and edge cases that even experienced users may not notice.

Take my own Allow for Comment Reply to Usernames With Less Than Three Characters in First Word for instance - when I first posted that question, nobody understood that particular aspect of the system, even though it was clearly documented in the faq.

I propose we introduce a simple and unobtrusive system of warnings that appear as users type. Right now, there is no indication of success or failure to the person typing the comment. This means that if they get it wrong, there's no way the error can be addressed unless someone goes up to him and say 'you're doing it wrong'. This is both a waste of time, and adds unnecessary noise to the already noisy comments.

I suggest that we start off with a simple message that simply informs the user of the system. This can be turned off for users with higher reputation:

alt text

Simple client side JavaScript can be used to determine whether the @username the user has typed is valid or not, and a simple simple warning can be shown if he makes a mistake:

alt text

Suggestions such as the one shown above can also be determined intelligently. Another typical issue found in comments is that the commenter will often try to address two different users in a single comment. The second @username will be ignored, but the commenter may not realise that is the case. This can also solve the problem:

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In addition, other forms of feedback can also be used. For instance, @usernames in existing comments can be highlighted, if only ever so slightly, and a tooltip be used to highlight what it's for:

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This will aid greatly in the discoverability of this feature, and since only successful use of the system will be picked up here, it should be plain to see if he has done anything wrong and need to edit. And always, there's the option of adding a 'help' link to the commenting interface, if only for new users:

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The key too all of the above suggestions is that there must be feedback to the user on whether or not his action was successful, or in this case, unsuccessful, and it is this aspect in which I find the current system lacking.

  • What about doing the same Tab-Auto-Complete that's used in the Chat? So as you type @Y it brings up all users who've contributed to the thread that start with Y.
    – ircmaxell
    Commented Jan 14, 2011 at 18:56
  • @ircmaxell That's for another [feature-req] - it's 3am now and I need to (yawn) sleep. Oh, and (shameless plug) rchern's SE mod script already does this
    – Yi Jiang
    Commented Jan 14, 2011 at 18:57
  • @Yi: but it would solve the problem indicated here (or at least make it clearer)...
    – ircmaxell
    Commented Jan 14, 2011 at 18:58
  • @YiJi, I'm good. How are you?
    – jjnguy
    Commented Jan 14, 2011 at 18:58
  • 1
    @ircmaxell Nice irony there. At any rate, I'm actually pretty sure there's already a tab-auto-complete suggestion. I'll dig it up after lunch.
    – Grace Note StaffMod
    Commented Jan 14, 2011 at 19:02
  • @YiJi, you should really add my username to your spell check dictionary...
    – jjnguy
    Commented Jan 14, 2011 at 19:05
  • @ircmaxell Here we go, here's the request for tab autocompletion. It predates chat, but essentially the function is identical.
    – Grace Note StaffMod
    Commented Jan 14, 2011 at 19:07
  • As an aside (I'm sure Yi Jiang already knows): using @Yi for Yi Jiang is actually supported since January 21st (but using @R. for R. Smith is not.)
    – Arjan
    Commented Jan 27, 2011 at 21:43
  • +1 I think there should be some sort of help text. I have pointed out how to reply to comments to new users perhaps 10 times just today. A lot of users just don't make the connection even when there are others comments with @usernames.
    – chibacity
    Commented Jan 27, 2011 at 21:49
  • Actually @R. works too (for R. Smith, not for R.Smith).
    – Arjan
    Commented Jan 28, 2011 at 8:22

3 Answers 3


There is now a help div for comments that is auto-expanded for low rep users.

Other users can click the help link under the comment submit button to see this comment help:

Comments use mini-Markdown formatting: [link](http://example.com) _italic_ **bold** `code`. The post author will automatically be notified of your comment. To notify a previous commenter, mention their user name: @peter or @PeterSmith will both work.

  • Could you add a screen shot of this, seeing as it's impossible to get hold of without having a second low-rep account?
    – Pekka
    Commented Feb 27, 2011 at 11:26
  • @pek click the help link under the add comment button as stated in the post Commented Feb 27, 2011 at 13:54
  • @Jeff ah, I didn't read you right. Cheers
    – Pekka
    Commented Feb 27, 2011 at 13:55
  • 1
    I personally would like to see the "To notify a previous commenter" part bolded. And would it be an idea to mention the fact that only the first @ will work? Not sure. Maybe a link to the full FAQ entry or Meta post would be in order?
    – Pekka
    Commented Feb 27, 2011 at 13:57
  • Or, instead of linking to the FAQ in the help box, maybe link to that from the Inbox, @Pekka and Jeff? (Especially since one is also notified if the post author answers your comment, even if they forget the @, if you are the only person who has commented so far. That might make folks wonder how one got to be notified.)
    – Arjan
    Commented Apr 3, 2011 at 12:14
  • @arjan good point but where would this link go? that's a very busy area already Commented Apr 3, 2011 at 21:34
  • Hmmm, usually it's enough when we write down some random thoughts, and then you & the team come up with something brilliant, @Jeff! ;-) But you're right, it is a busy area. Even a "what's this?" link when the Inbox is active doesn't really fit.
    – Arjan
    Commented Apr 4, 2011 at 7:25

I like this proposal but have a few caveats:

Comments often have names so that their audience is aware of who is being addressed, but often comments are intended for anyone reading the question or answer to which they are attached. Such comments do not have an @name nor should they.

Comments addressed to certain users with excessively long names or misleading ones (please_delete_me, for example) are typically shortened not because of discourtesy, but because the entire name seems pointless to spell out. Just as URL's are shortened (stackoverflow.com/.../20101) such usernames might also be shortened in a link.

Finally, is there any real point to having the correct username linked? There is no automatic linking between usernames and @usernames (that I am aware of). (See this question: Change all @username references in comments when a user changes their name?). I personally do not see a reason to enforce proper linking, given that it's never been done before and does not appear broken.

  • 2
    I think maybe you misunderstood the example; it's not warning about "@Yi" because it's an incomplete display name, it's warning because two characters isn't enough to alert anyone; you need at least three. If the person typed "@YiJ" it wouldn't warn, because that matches @YiJiang Commented Jan 14, 2011 at 19:27
  • What if someone comes along later with the name YiJoo and adds a comment. The existing @YiJ is now no longer sufficient to provide disambiguation.
    – JYelton
    Commented Jan 14, 2011 at 19:34
  • @JYelton I'm not entirely sure if I understand you correctly here - re: linking, I do not believe I have mentioned that - I simply said highlighting, like chat does right now. Re: multiple users with names starting with the same few chars, the comment reply rules also dealt with that. Can you clarify what you're talking about?
    – Yi Jiang
    Commented Jan 15, 2011 at 13:49
  • @YiJiang, reading between the lines, I don't think that JYelton has understood that the purpose of @ is that users get notified of comments that are addressed to them...
    – Benjol
    Commented Jan 24, 2011 at 9:59
  • @mich this is no longer true, we use implicit word breaks to make @yi a three letter match.. it matches @yi<WORD BREAK> Commented Jan 25, 2011 at 7:51
  • @Michael, like Jeff noted: using @Yi for Yi Jiang is actually supported since January 21st (but using @R. for R. Smith is not.)
    – Arjan
    Commented Jan 27, 2011 at 21:54
  • 1
    @Arjan Note how Michael's comment is from January 14th
    – Grace Note StaffMod
    Commented Jan 27, 2011 at 22:01
  • @Michael, actually @R. works too (for R. Smith, not for R.Smith.)
    – Arjan
    Commented Jan 28, 2011 at 8:20

How long is a comment thread typically? If one is sufficiently invested to comment on a question or answer, I would have thought it is easier to ping everyone who have already left comments automatically. (Or has this been previously proposed? I'm relatively new..)

If required, this could be added as a user option, but having been with SO/SE for 2 weeks, it doesn't look like there's much to tweak at a user level, except some things stay with cookies like whether you prefer the votes or newest in your stats page.

  • 1
    It's been previously suggested, and declined. Just because I placed a comment doesn't mean I'm interested in every little exchange, especially when it comes to a heated back-and-forth between two users. It's rarer that you'll need to ping everyone than you would need to ping a single user.
    – Grace Note StaffMod
    Commented Jan 27, 2011 at 21:42
  • Even notifying all commenters only when the original author posts a new comment, has been declined: Notify commenters of replies from newbie OPs.
    – Arjan
    Commented Jan 27, 2011 at 21:59

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