How to set Paperclip :default_url according User gender and asset style?

Through this gist script I can get default url for paperclip with user gender. But I want to get :style too. Someone know ho开发者_如何学JAVAw to?

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Default way of doing this:

#Assuming you default images are stored in app/assets/images/somedirectory

has_attached_file :attachment, default_url: :some_function

def some_function
   "somedirectory/:style/:class/#{self.gender}.png"
end

or using lambda:

has_attached_file :attachment, default_url: lambda{|attachment| "somedirectory/:style/:class/#{attachment.instance.gender}.png" }

Tested in Rails 4.