From: Brian Candler <b.candler@...>
Date: 2011-09-29T18:00:43+09:00
Subject: Re: What does "exit_on_fail("initialize") { hook('preinit') { preinit } } " mean?

Yunfeng Xu wrote in post #1024181:
> I can't understand why "exit_on_fail("initialize") { hook('preinit') {
> preinit } } " can be part of a statement together. I looked through some
> ruby books, but found no answer.

Read a section about 'blocks'. e.g. 
http://www.ruby-doc.org/docs/ProgrammingRuby/html/tut_containers.html#S2

Here you're not passing a block to be iterated (called multiple times), 
but something to be called later on.

class Foo
  def prepare(&blk)
    puts "I got a block! I'm going to run it later"
    @my_block = blk
  end
  def doit
    @my_block.call
  end
end

f = Foo.new
f.prepare { puts "Goodbye cruel world" }
puts "OK it's stored"
f.doit

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