Jesús Gabriel y Galán
5/26/2008 10:16:00 AM
On Mon, May 26, 2008 at 11:56 AM, Kimmo Lehto <kimmo.lehto@gmail.com> wrote:
> Any ideas how to do something like this..?
>
> I'd like to drop new parsers into a plugin-directory of my app without
> making modifications to the main app, so there would be something like:
>
> # main.rb:
> require 'plugins/*'
> parsed_data = Parser.parse_data(data_goes_here)
>
> # plugins/foo.rb:
> class FooParser < Parser
> handles /^foo/
> def parse_data(data)
> data.do_something if data.match(@handles)
> end
> end
>
> # plugins/bar.rb:
> class BarParser < Parser
> handles /^bar/
> def parse_data(data)
> data.do_something if data.match(@handles)
> end
> end
>
> Then if I wanted to add a new parser i would just throw it in there with
> the rest. Perhaps some sort of "register_handler"-call in each plugin?
I think you already have it. The "handles" method could be implemented
to register every handler, and then instantiate a child parser based on
which handler the data matches. You would need to move the "if data.match..."
part to the parent Parser class. Something like:
class Parser
@handlers = {}
class << self
attr_accessor :handlers
def handles reg
Parser.handlers[reg] = self
end
def parse_data data
handler = @handlers.keys.find {|x| data.match(x)}
raise "No parser found for #{data}" unless handler
parser = @handlers[handler]
parser.new.parse_data data
end
end
end
class FooParser < Parser
handles /^foo/
def parse_data data
puts "FooParser parsing #{data}"
end
end
class BarParser < Parser
handles /^bar/
def parse_data data
puts "BarParser parsing #{data}"
end
end
Hope this helps,
Jesus.