Strange behavior of alias_method_chains

rubyonrails-talk
1

Greetings.

I've got very strange behavior of alias_method_chains, and I hope someone will advise me.

I have a rails 2.2.2 app created with #rails aliasApp

, a class XYZ residing in app/helpers/xyz.rb:

<code> class XYZ

  attr_accessor :name   attr_accessor :value

  def initialize (a, b)     puts "in XYZ constructor"     self.name = a     self.value = b   end

  def a     puts self.name   end

  def b     puts self.value   end end </code>

, and an extended class XYZ in app/views/xyz_ext.rb

<code> class XYZ    def initialize_with_extension a,b       puts "before chain"       initialize_without_extension a,b       puts "after chain"    end    alias_method_chain :initialize, :extension end </code>

So basically what I expect to have three lines in the console when creating XYZ: 1) before chain 2) in Alias constructor 3) after chain

BUT I get something really different!

silencio:alias u2$ script/console Loading development environment (Rails 2.2.2)

require 'app/views/xyz_ext.rb'

=> ["XYZ"]

XYZ.new 1,3

before chain ArgumentError: wrong number of arguments (2 for 0) from ./app/views/xyz_ext.rb:4:in `initialize_without_extension' from ./app/views/xyz_ext.rb:4:in `initialize' from (irb):3:in `new' from (irb):3

Any ideas on this error would be very appreciated! Alex

2

The problem here is that the "normal" XYZ in xyz.rb is never loaded so
you're trying to call Object's initialize, which does not take 2
arguments

Fred

3

Fred,

I really appreciate your help. The following works like a charm.

silencio:alias u2$ script/console Loading development environment (Rails 2.2.2)

require 'app/helpers/alias.rb'

=> ["XYZ"]

require 'app/views/alias_ext.rb'

=>

XYZ.new 1,2

before chain in Alias constructor after chain => #<XYZ:0x259c73c @value=2, @name=1>

But having this in mind, how do I ensure that my 'app/helpers/alias.rb' is loaded BEFORE any extended classes? Sorry if this a really newbie question..

Alex

Frederick Cheung wrote:

4

Require it explicitly from the extension file ?

5

Thanks again!

Frederick Cheung wrote: