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Evan’s just released another Sydney while the Ruby-Core list is alive with bug reports and input from the core team. Nobu spotted a problem with user-defined literals and I was like, “oh, right, I need to try that.”

Add your methods to the PercentExpansion module. So, if you want your own %y, do like:

 require 'yaml'
 module PercentExpansion
   def y( str, m ); YAML::load( str ) end
 end

 METADATA = %y{
   author: _why
   date: 2005-07-13 09:10:12 -05:00
   title: User-defined Literals
 }

Or for fetching a URI:

 require 'open-uri'
 module PercentExpansion
   def fetch( str, m )
     URI.parse( str ).open do |urif|
       urif.read
     end
   end
 end

 ruby_terms = %fetch{http://ruby-lang.org/en/LICENSE.txt}

Sydney bars you from overriding the default literals. Which is probably safe. But, you know, I have to wonder what sort of hacks we’d see if these could be overridden.

Or if the string itself could be overturned. One thought: interpolation could be restyled in midair. R is for recklesssnessss.