Removing the hard coding of export formats allowing the user to 'plug-in' their own export format.

lib/foreman/cli.rb

@@ -1,10 +1,14 @@
 require "foreman"
+require "foreman/helpers"
 require "foreman/engine"
 require "foreman/export"
 require "thor"
 require "yaml"
 
 class Foreman::CLI < Thor
+  include Foreman::Helpers
+
+  class_option :procfile, :type => :string, :aliases => "-f", :desc => "Default: Procfile"
 
   desc "start", "Start the application"
 
@@ -42,16 +46,14 @@ class Foreman::CLI < Thor
   def export(format, location=nil)
     check_procfile!
 
-    formatter = case format
+    classy_format = classify(format)
-      when "inittab" then Foreman::Export::Inittab
+    formatter     = constantize("Foreman::Export::#{ classy_format }")
-      when "upstart" then Foreman::Export::Upstart
-      when "bluepill" then Foreman::Export::Bluepill
-      when "runit"    then Foreman::Export::Runit
-      else error "Unknown export format: #{format}."
-    end
 
     formatter.new(engine).export(location, options)
 
+  rescue NameError => ex
+    error "Unknown export format: #{format}."
+    raise ex
   rescue Foreman::Export::Exception => ex
     error ex.message
   end

lib/foreman/helpers.rb

@@ -0,0 +1,50 @@
+module Foreman::Helpers
+  # Copied whole sale from, https://github.com/defunkt/resque/
+
+  # Given a word with dashes, returns a camel cased version of it.
+  #
+  # classify('job-name') # => 'JobName'
+  def classify(dashed_word)
+    dashed_word.split('-').each { |part| part[0] = part[0].chr.upcase }.join
+  end
+
+  # Tries to find a constant with the name specified in the argument string:
+  #
+  # constantize("Module") # => Module
+  # constantize("Test::Unit") # => Test::Unit
+  #
+  # The name is assumed to be the one of a top-level constant, no matter
+  # whether it starts with "::" or not. No lexical context is taken into
+  # account:
+  #
+  # C = 'outside'
+  # module M
+  #   C = 'inside'
+  #   C # => 'inside'
+  #   constantize("C") # => 'outside', same as ::C
+  # end
+  #
+  # NameError is raised when the constant is unknown.
+  def constantize(camel_cased_word)
+    camel_cased_word = camel_cased_word.to_s
+
+    if camel_cased_word.include?('-')
+      camel_cased_word = classify(camel_cased_word)
+    end
+
+    names = camel_cased_word.split('::')
+    names.shift if names.empty? || names.first.empty?
+
+    constant = Object
+    names.each do |name|
+      args = Module.method(:const_get).arity != 1 ? [false] : []
+
+      if constant.const_defined?(name, *args)
+        constant = constant.const_get(name)
+      else
+        constant = constant.const_missing(name)
+      end
+    end
+    constant
+  end
+end