middleman namespacing

# data/prefix.yml
css: "slds-"


# helpers/ds_helpers.rb
module DsHelpers
  def pf(*classes)
    classes.map! { |x| "#{data.prefix.css}#{x}" }.join(' ')
  end
end



# in html wherever
<p class="<%= pf 'foo', 'goo', 'boo' %>">
  Some content text
</p>

<hr class="<%= pf 'bar', 'har', 'yar' %>" />



# output in view source
<p class="slds-foo slds-goo slds-boo">
  Some content text
</p>

<hr class="slds-bar slds-har slds-yar" />

Big thanks to @brixen & @swrainey for the pointers.