From: "James M. Lawrence" <quixoticsycophant@...>
Date: 2008-09-17T10:58:07+09:00
Subject: Re: define anonymous module with closure


Ara Howard wrote:
> cfp:~ > ruby a.rb
> "x"
> you need to do it this way if you want your method to take a block

...if you are constrained to 1.8.6.

% ruby --version
ruby 1.8.7 (2008-08-11 patchlevel 72)

  class A
    define_method(:f) { |x, &block|
      puts "A#f argument: #{x}"
      block.call(88)
    }
  end

  A.new.f(99) { |t|
    puts "block called with: #{t}"
  }
  # =>  A#f argument: 99
  #     block called with: 88

Now if you want default parameters, you'll need Ara's example again.
Unless you use 1.9...

% ruby --version
ruby 1.9.0 (2008-09-15 revision 19346)

  class A
    t = ->(a = 11, b = 22) { a + b }
    define_method(:g, &t)
  end

  a = A.new
  p a.g           # => 33
  p a.g(33)       # => 55
  p a.g(33, 44)   # => 77

From what I gathered, -> was introduced because

  lambda { |a = 11, b = 22| a + b }

was too difficult or ambiguous to parse.  My feeling is that -> should
be avoided if at all possible, no matter how difficult.

To me, -> is a step toward ruby jumping the shark.  I want to yell,
"Fonzie, don't do it!"  (Excuse the Americanisms.)
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