I like this suggestion, although I don't think that's the right regexp to use for an outline. Shouldn't it be limited to definitions only (similar to what imenu typically does)? 

On Wed, Jul 6, 2022, at 2:48 AM, Yilkal Argaw wrote:
> > Hello guys.
> > Some programming modes built into emacs provide outline-regexp to
> > allow for code folding and an example of this is python-mode.
> > "ruby-mode" on the other hand does does not have this feature. Since
> > it is a very handy feature to have it might be worth adding with the
> > following simple patch.
> >
> > diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
> > index a197724634..6437b84628 100644
> > --- a/lisp/progmodes/ruby-mode.el
> > +++ b/lisp/progmodes/ruby-mode.el
> > @@ -2447,6 +2447,7 @@ ruby--prettify-symbols-alist
> >      ("lambda" . ?λ))
> >    "Value for `prettify-symbols-alist' in `ruby-mode'.")
> >
> > +
> >  ;;;###autoload
> >  (define-derived-mode ruby-mode prog-mode "Ruby"
> >    "Major mode for editing Ruby code."
> > @@ -2465,7 +2466,8 @@ ruby-mode
> >                                     ((?_ . "w"))))
> >    (setq-local prettify-symbols-alist ruby--prettify-symbols-alist)
> >
> > -  (setq-local syntax-propertize-function #'ruby-syntax-propertize))
> > +  (setq-local syntax-propertize-function #'ruby-syntax-propertize)
> > +  (setq-local outline-regexp ruby-indent-beg-re))
> >
> >  ;;; Invoke ruby-mode when appropriate
> > Sorry I just noticed the extra line break after I pressed send. Here is the
> > patch without that line break.
> 
> diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
> index a197724634..7a62d72e06 100644
> --- a/lisp/progmodes/ruby-mode.el
> +++ b/lisp/progmodes/ruby-mode.el
> @@ -2465,7 +2465,8 @@ ruby-mode
>                                     ((?_ . "w"))))
>    (setq-local prettify-symbols-alist ruby--prettify-symbols-alist)
> 
> -  (setq-local syntax-propertize-function #'ruby-syntax-propertize))
> +  (setq-local syntax-propertize-function #'ruby-syntax-propertize)
> +  (setq-local outline-regexp ruby-indent-beg-re))
> 
> ;;; Invoke ruby-mode when appropriate
> 
> 
> 
> On Wed, Jul 6, 2022 at 2:28 AM Yilkal Argaw
> <yilkalargawworkneh@gmail.com> wrote:
> >
> > Hello guys.
> > Some programming modes built into emacs provide outline-regexp to
> > allow for code folding and an example of this is python-mode.
> > "ruby-mode" on the other hand does does not have this feature. Since
> > it is a very handy feature to have it might be worth adding with the
> > following simple patch.
> >
> > diff --git a/lisp/progmodes/ruby-mode.el b/lisp/progmodes/ruby-mode.el
> > index a197724634..6437b84628 100644
> > --- a/lisp/progmodes/ruby-mode.el
> > +++ b/lisp/progmodes/ruby-mode.el
> > @@ -2447,6 +2447,7 @@ ruby--prettify-symbols-alist
> >      ("lambda" . ?λ))
> >    "Value for `prettify-symbols-alist' in `ruby-mode'.")
> >
> > +
> >  ;;;###autoload
> >  (define-derived-mode ruby-mode prog-mode "Ruby"
> >    "Major mode for editing Ruby code."
> > @@ -2465,7 +2466,8 @@ ruby-mode
> >                                     ((?_ . "w"))))
> >    (setq-local prettify-symbols-alist ruby--prettify-symbols-alist)
> >
> > -  (setq-local syntax-propertize-function #'ruby-syntax-propertize))
> > +  (setq-local syntax-propertize-function #'ruby-syntax-propertize)
> > +  (setq-local outline-regexp ruby-indent-beg-re))
> >
> >  ;;; Invoke ruby-mode when appropriate
> 
>