Add support for proc arg for fog_public (#2302)

lib/paperclip/storage/fog.rb

@@ -86,11 +86,14 @@ module Paperclip
       end
 
       def fog_public(style = default_style)
-        if @options.has_key?(:fog_public)
-          if @options[:fog_public].respond_to?(:has_key?) && @options[:fog_public].has_key?(style)
-            @options[:fog_public][style]
+        if @options.key?(:fog_public)
+          value = @options[:fog_public]
+          if value.respond_to?(:key?) && value.key?(style)
+            value[style]
+          elsif value.respond_to?(:call)
+            value.call(self)
           else
-            @options[:fog_public]
+            value
           end
         else
           true

spec/paperclip/storage/fog_spec.rb

@@ -273,6 +273,22 @@ describe Paperclip::Storage::Fog do
         end
       end
 
+      context "with fog_public as a proc" do
+        let(:proc) { ->(attachment) { !attachment } }
+
+        before do
+          rebuild_model(@options.merge(fog_public: proc))
+          @dummy = Dummy.new
+          @dummy.avatar = StringIO.new(".")
+          @dummy.save
+        end
+
+        it "sets the @fog_public instance variable to false" do
+          assert_equal proc, @dummy.avatar.instance_variable_get("@options")[:fog_public]
+          assert_equal false, @dummy.avatar.fog_public
+        end
+      end
+
       context "with styles set and fog_public set to false" do
         before do
           rebuild_model(@options.merge(fog_public: false, styles: { medium: "300x300>", thumb: "100x100>" }))