From: Josh Cheek <josh.cheek@...>
Date: 2010-01-16T05:53:58+09:00
Subject: Nested Function Confusion

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Hi, couldn't find any explanation of nested functions (other than an
acknowledgment of their existence) in Programming Ruby or the Ruby
Programming Language, so thought I'd see what people here could tell me.

I'm having a difficult time understanding what is going on in this example:
def test
  def test2
  end
end

RUBY_VERSION            # => "1.8.6"
defined? test           # => "method"
defined? test2          # => nil

defined? test::test2    # => "method"
defined? test2          # => "method"

defined? test           # => "method"
methods.grep( /test/ )  # => ["test2"]

The first time I check whether test2 is defined, it returns nil, the second
time it returns "method"
When I check if test is defined, it returns 'method' but when I type
methods.grep(/test/) it only finds "test2"


Also, when should nested functions/methods be used?
Are nested functions redefined upon each call to the outer function?
Are there scope restrictions that would make it sensible to use nested
functions to enforce encapsulation of interdependent logic?

Thanks,
Josh

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