A ruby DSL for building long complex regular expressions used frequently across large data extraction projects.

This is the simplest possible example, but given the following text:
t = "$10.99 (555) 444-3322 Boston, MA"

Instead of writing a regular expression like the following:
data = t.match(/\$(\d+[,\d]*\.\d+)\s*(\(\d{3}\)\s\d{3}-\d{4})\s*(\w+),\s(\w+)/)

and then retrieving the data with match result indices:
data[1] => "10.99"
data[2] => "(555) 444-3322"
data[3] => "Boston"
data[4] => "MA"

We can use Houdini to build the regular expression in easy to read and reusable pieces

Define a regular expression for use across your project:
Houdini.define(:word, /\w+/)

Call hmatch or hscan on a string and build your expression pieces with the r() method by defining the expression inline or using a pre-defined expression.  Then build your match results with the m( ) method.

data = t.hmatch do
  r(/\d+[,\d]*\.\d+/, "amount")
  r(/\(\d{3}\)\s+\d{3}-\d{4}/, "phone_number")
  r(:word, "city", "state")
  m("\\$(amount) (phone_number) (city), (state)")
end

Now you can access the data as methods on the resulting object:

data.amount        => "10.99"
data.phone_number  => "(555) 444-3322"
data.city          => "Boston"
data.state         => "MA"

or access the original MatchData object

data.match =>  #<MatchData "$10.99 (555) 444-3322 Boston, MA" 1:"10.99" 2:"(555) 444-3322" 3:"Boston" 4:"MA">