It'd be better to have the constant moved to the top of the class (before :initialize) like how it is for classes under Jekyll namespace..

Would it be better to just inline it?
I wanted to keep it close to where it is being used. If this class gets too complicated, it should be split out into a separate file. Maybe it's time for that anyway?

If it has to be a regex, then lets inline it with a frozen definition.. (so its still a constant..)
Regarding the move to a new file.., nope.. I'm against it because, this is not a class in our namespace..

It would live at lib/kramdown/parser/smartypants.rb

Prior discussion: #4323 (comment)

true.. but if core is going to consider making the switch to CommonMark, I feel this abstraction is futile..

the regex looks weird to me.. "match something that starts with nothing"...
Also, consistency-wise.. we use regexes with \A instead of ^ (not that it matters..)

Yeah, it's weird looking, but do you have a better suggestion?

I will use \A instead of ^. Thanks for catching that 👍

I'm searching for the source to :define_parser.. can't seem to find it..

found it.. placing it here for quick reference..

      # Add a parser method
      #
      # * with the given +name+,
      # * using +start_re+ as start regexp
      # * and, for span parsers, +span_start+ as a String that can be used in a regexp and
      #   which identifies the starting character(s)
      #
      # to the registry. The method name is automatically derived from the +name+ or can explicitly
      # be set by using the +meth_name+ parameter.
      def self.define_parser(name, start_re, span_start = nil, meth_name = "parse_#{name}")
        raise "A parser with the name #{name} already exists!" if @@parsers.has_key?(name)
        @@parsers[name] = Data.new(name, start_re, span_start, meth_name)
      end

k.. I can't come up with a better alternative for the regex.. let's go ahead with %r!\A!..

We need something that always matches, but never consumes any of the actual string 😆

I think %r!\A! communicates this as well as anything could, it's just odd.

4 \s here....

doh!