[PATCH] oldweb: apply LessHtml monkey patch late, at runtime

[Eric Wong <e@80x24.org>]

RDoc will load oldweb.rb regardless of whether it is used or
not, so do not apply our monkey patching to reduce HTML
generated by RDoc::Markup::ToHtml until we initialize Oldweb.

Thanks to Daniel Ferreira for noticing this in [ruby-talk:437390]:
  http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/437390
  <CAPL_2g25ir4ZBJo652ao1EYB59ZvFHhpGef1V14QOV2SeVXLeA@mail.gmail.com>

This still assumes any Ruby VM instance (currently synonymous
with an OS process in Ruby 2.4) will only use one RDoc template
in its lifetime and not switch between them.  More work will be
required to support switching between `oldweb' and other
templates within the same VM instance, but that's not a priority
for me.
---
 lib/oldweb.rb | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/lib/oldweb.rb b/lib/oldweb.rb
index a5da1cc..95b7171 100644
--- a/lib/oldweb.rb
+++ b/lib/oldweb.rb
@@ -31,6 +31,8 @@ class Oldweb
     RDoc::Text::TO_HTML_CHARACTERS[Encoding::UTF_8] =
       RDoc::Text::TO_HTML_CHARACTERS[Encoding::ASCII]
 
+    less_html!
+
     @store = store
     @options = options
     @base_dir = Pathname.pwd.expand_path
@@ -298,12 +300,13 @@ class Oldweb
       @res << "</h#{level}>"
     end
   end
-end
 
-# :stopdoc:
-class RDoc::Markup::ToHtml # :nodoc:
-  remove_method :accept_heading
-  remove_method :accept_verbatim
-  include Oldweb::LessHtml
+  def less_html! # :nodoc:
+    klass = RDoc::Markup::ToHtml
+    return if klass.include?(Oldweb::LessHtml)
+    klass.__send__(:remove_method, :accept_heading)
+    klass.__send__(:remove_method, :accept_verbatim)
+    klass.__send__(:include, Oldweb::LessHtml)
+  end
 end
 # :startdoc:
-- 
EW