# BUG: ruby-mode.el : '/=' operator breaks following indentati **URL:** \ **Category:** Ruby\ **Created:** [November 30, 2006, 12:35am UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725 "2006-11-30T00:35:54Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [November 30, 2006, 12:35am UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/1 "2006-11-30T00:35:54Z")
Using emacs 21.4, ruby-mode.el from Ruby 1.8.5 (byte-compiled), if I open a file with the following code … def foo x /= y bar end …move the cursor to the word “bar” and press Tab, nothing happens! If I replace “/=” with “\*=” then Tab fixes the indentation as I’d expect. Any suggestions for debugging this? I’ve hacked elisp a few times but major mode definitions are beyond my experience. Regards, Jeremy H. ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [November 30, 2006, 5:36am UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/2 "2006-11-30T05:36:36Z")
On 11/30/06, Jeremy H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > expect. > > Any suggestions for debugging this? I’ve hacked elisp a few times but > major mode definitions are beyond my experience. The issue is probably that it’s treating the “/=” as the beginning of a multiline regexp. A common fix for these sorts of “mistaken delimiters” is to put a comment at the end of the line containing a closing delimiter: def foo x /= y #/ bar end Not ideal, but it might get you by. BTW, there’s a newer ruby-mode.el in the ruby CVS repository. It still doesn’t fix this, although the behavior is slightly different (it doesn’t indent the “bar” at all, as if in a multiline string). G. ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [November 30, 2006, 5:36am UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/3 "2006-11-30T05:36:38Z")
11/30/06, George O. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > BTW, there’s a newer ruby-mode.el in the ruby CVS repository. It > still doesn’t fix this, although the behavior is slightly different > (it doesn’t indent the “bar” at all, as if in a multiline string). Oops, I misread. It sounds like it is the same behavior. Still, it might be a newer version. ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [November 30, 2006, 12:41pm UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/4 "2006-11-30T12:41:36Z")
On 2006-11-30, George O. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > The issue is probably that it’s treating the “/=” as the beginning > of a multiline regexp. A common fix for these sorts of “mistaken > delimiters” is to put a comment at the end of the line containing a > closing delimiter: > > def foo > x /= y #/ > bar > end Thanks, that works. A slightly better fix is to add a ‘;’ as well to convince the major mode that the statement has ended, otherwise it adds extra indentation to the next line. def foo x /= y # / ; bar end I wonder how the Ruby parser decides that /= is an operator and not the start of a regexp? Regards, Jeremy H. ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [December 1, 2006, 1:45pm UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/5 "2006-12-01T13:45:46Z")
On 11/30/06, Jeremy H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Thanks, that works. A slightly better fix is to add a ‘;’ as well to > convince the major mode that the statement has ended, otherwise it > adds extra indentation to the next line. > > def foo > x /= y # / ; > bar > end Hmm, my ruby-mode doesn’t seem to need the ‘;’. I’m using the CVS HEAD version with XEmacs 21.4.19. > I wonder how the Ruby parser decides that /= is an operator and not > the start of a regexp? It’s just the way the grammar is defined. For it to be a regexp, you’d need parens on the call to #x. g@crash:~$ cat test.rb x /=/ g@crash:~$ ruby test.rb test.rb:1: unterminated string meets end of file test.rb:1: parse error, unexpected tSTRING\_END, expecting tSTRING\_CONTENT or tREGEXP\_END or tSTRING\_DBEG or tSTRING\_DVAR g@crash:~$ cat test2.rb x(/=/) g@crash:~$ ruby test2.rb test2.rb:1: undefined method `x’ for main:Object (NoMethodError) g@crash:~$ ruby -v ruby 1.8.4 (2005-12-24) [i686-linux] The ruby-mode parser is much simpler than the one the ruby interpreter uses. For a start, it’s not based on a proper grammar. I don’t suppose someone’s tried to use semantic [1] or something to produce something a little more robust? [1] [http://www.xemacs.org/Documentation/packages/html/semantic.html](http://www.xemacs.org/Documentation/packages/html/semantic.html) ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [December 1, 2006, 11:01pm UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/6 "2006-12-01T23:01:54Z")
On 2006-12-01, George O. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Hmm, my ruby-mode doesn’t seem to need the ‘;’. I’m using the CVS > HEAD version with XEmacs 21.4.19. Mine definitely does need it. I’m using stock Ruby 1.8.5 and GNU Emacs 21.4 . > > I wonder how the Ruby parser decides that /= is an operator and not > > the start of a regexp? > > It’s just the way the grammar is defined. “Mommy, why is the sky blue?” “Hush child, it’s just the way the physics is defined.” 🙂 > For it to be a regexp, you’d need parens on the call to #x. Hmm, so after an identifier the parser tries to parse an infix operator trying to parse an expression, whereas after an open paren there can’t be an infix operator so it parses “/=” as the start of a regexp? If so, I wonder how easy it would be to fix the emacs major mode to do the same thing? Thanks for your help. Regards, Jeremy H. ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [December 4, 2006, 4:59pm UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/7 "2006-12-04T16:59:39Z")
Hi, In message “Re: BUG: ruby-mode.el : ‘/=’ operator breaks following indentation” on Thu, 30 Nov 2006 08:35:06 +0900, Jeremy H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) writes: |Using emacs 21.4, ruby-mode.el from Ruby 1.8.5 (byte-compiled), if I |open a file with the following code … | |def foo | x /= y | bar |end Does this patch work for you? ``` matz. ``` diff --git a/misc/ruby-mode.el b/misc/ruby-mode.el index 38d5b71…33c5901 100755 — a/misc/ruby-mode.el +++ b/misc/ruby-mode.el @@ -383,6 +383,8 @@ The variable ruby-indent-level controls the amount of indentation. (t (setq in-string (point)) (goto-char end)))) - ``` ((looking-at "/=") ``` - (goto-char pnt)) ((looking-at “/”) (cond ((and (not (eobp)) (ruby-expr-beg 'expr-re)) ---
**Author:** ![jeremyheiler](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/34f0e0/32.png) [@jeremyheiler](https://www.ruby-forum.com/u/jeremyheiler)\ **Post date:** [December 4, 2006, 7:32pm UTC](https://www.ruby-forum.com/t/bug-ruby-mode-el-operator-breaks-following-indentati/77725/8 "2006-12-04T19:32:15Z")
On 2006-12-04, Yukihiro M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Does this patch work for you? Yes. Thank you! Jeremy H.