From: Yunfeng Xu <hywl51@...>
Date: 2011-09-30T16:49:17+09:00
Subject: Re: What does "exit_on_fail("initialize") { hook('preinit') { preinit } } " mean?

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Thank for Candler. I have gotten it.

For other newbies like me, I suggest read the book "The Ruby Programming
Language" that has many details about block grammar.


On Thu, Sep 29, 2011 at 5:00 PM, Brian Candler <b.candler@pobox.com> wrote:

> 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
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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