Interpolate URLs using a string rather than a regex

lib/paperclip/interpolations.rb

@@ -30,7 +30,7 @@ def self.all
     def self.interpolate pattern, *args
       pattern = args.first.instance.send(pattern) if pattern.kind_of? Symbol
       all.reverse.inject(pattern) do |result, tag|
-        result.gsub(/:#{tag}/) do |match|
+        result.gsub(":#{tag}") do |match|
           send( tag, *args )
         end
       end

spec/paperclip/interpolations_spec.rb

@@ -204,7 +204,7 @@ def url(*args)
     attachment.stubs(:original_filename).returns("one")
     assert_equal "one", Paperclip::Interpolations.filename(attachment, :style)
   end
-  
+
   it "returns the basename when the extension contains regexp special characters" do
     attachment = mock
     attachment.stubs(:styles).returns({})
@@ -249,4 +249,12 @@ def url(*args)
     value = Paperclip::Interpolations.interpolate(":notreal/:id/:attachment", :attachment, :style)
     assert_equal ":notreal/1234/attachments", value
   end
+
+  it "handles question marks" do
+    Paperclip.interpolates :foo? do
+      "bar"
+    end
+    value = Paperclip::Interpolations.interpolate(":fo/:foo?")
+    assert_equal ":fo/bar", value
+  end
 end