Error: Attempt to call private method

Question

Coming from a long history of C-style syntax and now trying to learn Ruby (on Rails), I've been having my share of issues with its idioms and such, but today I hit one I didn't expect to have a problem with and I can't see whatever it is that must be right in front of my face.

I have a Binary class that includes a private method to derive a URI value from a path value (uri and path are attributes of the class). I'm calling self.get_uri_from_path() from within Binary.upload(), but I get:

Attempt to call private method 

A snippet of the model looks like this:

class Binary < ActiveRecord::Base   has_one :image    def upload( uploaded_file, save = false )     save_as = File.join( self.get_bin_root(), '_tmp', uploaded_file.original_path )      # write the file to a temporary directory     # set a few object properties      self.path   = save_as.sub( Rails.root.to_s + '/', '' )     self.uri    = self.get_uri_from_path()   end    private    def get_uri_from_path     return self.path.sub( 'public', '' )   end end 

Am I making the call incorrectly? Am I missing something else that's even more fundamental? The only place that Binary.get_uri_from_path() is being called from - at the moment - is Binary.upload(). I'd expect to be able to call a private method from within the same class unless Ruby does something markedly different from other languages I've used.

Thanks.

Answer 1

Don't do

self.get_uri_from_path() 

do

get_uri_from_path() 

Because...

  class AccessPrivate     def a     end     private :a # a is private method      def accessing_private       a              # sure!        self.a         # nope! private methods cannot be called with an explicit receiver at all, even if that receiver is "self"       other_object.a # nope, a is private, you can't get it (but if it was protected, you could!)     end   end 

via