melborne · August 29, 2015 13:57 · Mar 5, 2014 · Mar 5, 2014
diff --git a/filter_usage.rb b/filter_usage.rb
@@ -0,0 +1,29 @@
+require './filter'
+using CoreExt
+
+puts 'hello' | :upcase
+# >> HELLO
+
+puts 123 | :next
+# >> 124
+
+puts 'Mississippi' | :upcase | :squeeze | :chars | :reverse
+# >> ["I", "P", "I", "S", "I", "S", "I", "M"]
+
+puts 123 | :next | :even?
+# >> true
+
+Filter.add :currency do |int|
+  raise ArgumentError unless int.is_a?(Numeric)
+  "$%.2f" % int
+end
+
+puts 123.45 * 3 | :currency
+# >> $370.35
+
+Filter.add :titleize do |str|
+  str.scan(/\w+/).map(&:capitalize)*' '
+end
+
+puts 'ruby on rails' | :titleize
+# >> Ruby On Rails
diff --git a/filter.rb b/filter.rb
@@ -0,0 +1,46 @@
+class Filter
+  class << self
+    def filters
+      @filters ||= {}
+    end
+
+    def add(name, &code)
+      filters[name] = code
+    end
+  end
+
+  def initialize(obj)
+    @methods = []
+    @obj = obj
+  end
+
+  def |(method)
+    @methods << method
+    self
+  end
+
+  def run
+    @methods.inject(@obj) do |mem, method|
+      if custom = Filter.filters[method]
+        custom.call(mem)
+      else
+        mem.send method
+      end
+    end
+  end
+
+  def to_s
+    run.to_s
+  end
+end
+
+module CoreExt
+  [Fixnum, Float, String].each do |klass|
+    refine klass do
+      def |(other)
+        return super unless other.is_a?(Symbol)
+        Filter.new(self) | other
+      end
+    end
+  end
+end