Creating a plugin based app

Ruby
1

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?

2

On Mon, May 26, 2008 at 11:56 AM, Kimmo L. [email protected]
wrote:

class FooParser < Parser
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.

3

Jesús Gabriel y Galán wrote:

Hope this helps,

Perfect, thanks.