From: Marc Heiler <shevegen@...>
Date: 2011-10-21T20:10:17+09:00
Subject: When is a method known to Ruby?

Hi.

When is a method "known" to the ruby parser and why?

Example 1, works:


  require 'pp'

  module Foo

    def self.foo(i) # i is a string that will be shortened.
      return i.chop
    end

    CONSTANT_1 = 'bla'
    CONSTANT_2 = foo('bla')

  end

  constants = Foo.constants
  pp Foo.foo 'abc'
  pp Foo::CONSTANT_2
  pp constants

  # This works, returns:
  # "ab"
  # "bl"
  #   ["CONSTANT_1", "CONSTANT_2"]


Example 2, does not work:

  require 'pp'

  module Foo

    CONSTANT_1 = 'bla'
    CONSTANT_2 = foo('bla')

    def self.foo(i) # i is a string that will be shortened.
      return i.chop
    end

  end

  constants = Foo.constants
  pp Foo.foo 'abc'
  pp Foo::CONSTANT_2
  pp constants

  # This does not work, returns:
  #  module_test.rb:6: undefined method `foo' for Foo:Module
(NoMethodError)



The difference is when def self.foo(i)
appears.

Apparently the parser must have "seen" it before working on it.

Can someone explain to me why, and if there is another workaround
other than moving the method definition before the method call
first happens?

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