Fix the collision with Object#hash.

Closes #678. Closes #450.

lib/paperclip/attachment.rb

@@ -284,7 +284,7 @@ module Paperclip
 
     # Returns a unique hash suitable for obfuscating the URL of an otherwise
     # publicly viewable attachment.
-    def hash(style_name = default_style)
+    def hash_key(style_name = default_style)
       raise ArgumentError, "Unable to generate hash without :hash_secret" unless @options[:hash_secret]
       require 'openssl' unless defined?(OpenSSL)
       data = interpolate(@options[:hash_data], style_name)

lib/paperclip/interpolations.rb

@@ -137,11 +137,11 @@ module Paperclip
       attachment.fingerprint
     end
 
-    # Returns a the attachment hash.  See Paperclip::Attachment#hash for
+    # Returns a the attachment hash.  See Paperclip::Attachment#hash_key for
     # more details.
     def hash attachment=nil, style_name=nil
       if attachment && style_name
-        attachment.hash(style_name)
+        attachment.hash_key(style_name)
       else
         super()
       end

test/attachment_test.rb

@@ -245,7 +245,7 @@ class AttachmentTest < Test::Unit::TestCase
 
       should "interpolate the hash data" do
         @attachment.expects(:interpolate).with(@attachment.options[:hash_data],anything).returns("interpolated_stuff")
-        @attachment.hash
+        @attachment.hash_key
       end
 
       should "result in the correct interpolation" do

test/interpolations_test.rb

@@ -195,14 +195,14 @@ class InterpolationsTest < Test::Unit::TestCase
   should "return attachment's hash when passing both arguments" do
     attachment = mock
     fake_hash = "a_wicked_secure_hash"
-    attachment.expects(:hash).returns(fake_hash)
+    attachment.expects(:hash_key).returns(fake_hash)
     assert_equal fake_hash, Paperclip::Interpolations.hash(attachment, :style)
   end
 
   should "return Object#hash when passing no argument" do
     attachment = mock
     fake_hash = "a_wicked_secure_hash"
-    attachment.expects(:hash).never.returns(fake_hash)
+    attachment.expects(:hash_key).never.returns(fake_hash)
     assert_not_equal fake_hash, Paperclip::Interpolations.hash
   end