From: Jeremy McAnally <jeremymcanally@...>
Date: 2008-04-04T13:14:42+09:00
Subject: Re: DSL implementation question

You'd do something like this:

def cfg_block(name, params={}, &block)
   # Other stuff
   my_obj.instance_eval &block
end

...where my_obj is the object that you were previously yielding. :)

--Jeremy

On Thu, Apr 3, 2008 at 11:49 PM, tender flake
<tenderflake@mailinator.com> wrote:
> Hello,
>
>  I'm trying to write a simple DSL to define memory maps of hardware
>  devices.
>  Something like:
>
>  cfg_block "top_device", :depth => 16 do
>   reg "ctrl_reg", :offset => 0, :mode => "RW"
>   reg "status_reg", :offset => 1, :mode => "R"
>  end
>
>  I've implemented something but I am not satisfied with it.
>
>  The problem I have is about scoping.  How can I make the reg command
>  in my
>  small DSL exemple above execute in the context of the object created
>  by the
>  cfg_block method?  The way I implemented this is by passing the
>  created
>  cfg_block object as a block parameter and then passing it to every reg
>  command.  E.g:
>
>  cfg_block "top_device", :depth => 16 do |__dev__|
>    reg "ctrl_reg",   __dev__,     :offset...
>  end
>
>  I consider this redundant since I'd like the context to provide the
>  cfg_block reference.  I tried multiple things but haven't figured it
>  out
>  using blocks.  Is there a way to get rid of __dev__?
>
>  Suggestions would be greatly appreciated.    Thanks in advance.
>
>  My implementation follows below:
>
>  module Register_defs
>
>    class Cfg_Block < Hash
>
>       def initialize(name, params={})
>          self[:name] = name
>          self[:regs] = {}
>          self.merge!(params)
>       end
>
>       def add_reg(reg)
>          self[:regs][reg[:name]] = reg
>       end
>
>    end
>
>    class Register < Hash
>       def initialize(name, cfg_block, params={})
>          self[:name] = name
>          self.merge!(params)
>          cfg_block.add_reg(self)
>       end
>
>    end
>
>    def cfg_block(name, params={})
>       cfg_block = Cfg_Block.new(name, params)
>       yield(cfg_block)
>       cfg_block
>    end
>
>    def reg(name, cfg_block, params={})
>       reg = Register.new(name, cfg_block, params)
>       yield(reg)
>       reg
>    end
>
>  end
>
>  include Register_defs
>
>  modules =  cfg_block "top_block" do |cb|
>
>    reg "reg1", cb, :addr => 0 do
>       # do something
>    end
>
>    reg "reg2", cb, :addr => 0 do
>       # do something else
>    end
>
>  end
>
>  p modules
>
>
>
>
>
>



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