Classes, methods and variables in ruby

Question

I am trying to write a plug-in system in ruby and I am running into a bit of trouble with never having learned a good set of fundamentals. Anyway my plug-in system is just an experiment in working with classes. My Plugin class looks like this:

class Plugin
  def info
    # Set some default values when a new class is created.
    name = "Test Plugin"
    description = "Just a simple test plugin."
    version = "1.0"
  end
end

In a plugin I would require the above file and write some code like so:

require "./_plugin_base.rb"

pluginCleanup = Plugin.new

pluginCleanup.info do
  name = "Cleanup"
  description = "Remove the files we don't need in the public folder."
  version = "1.0"
end

Now, I know this code does not work. Basically what I think I want are instance variables under the info method. I have tried using true instance variables and they do work well however I want to keep these inside the info function if that makes any sense., because when I do use attr_accessor the varibles are accessable as:

pluginCleanup.name = "New Value"

Can someone tell me how I would make the code work as described in the examples above? I just want to be able to declare a new instance and call:

pluginCleanup.info.name = "New Value"

PreciousBodilyFluids · Accepted Answer · 2011-04-28 06:13:28Z

2

What do you think of this?

class Plugin
  def initialize
    @info = PluginInfo.new
  end

  attr_reader :info
end

class PluginInfo
  def initialize
    # Set some default values when a new class is created.
    @name = "Test Plugin"
    @description = "Just a simple test plugin."
    @version = "1.0"
  end

  attr_accessor :name, :description, :version
end

plugin_cleanup = Plugin.new
 #=> #<Plugin:0x000000024f0c48 @info=#<PluginInfo:0x000000024f0c20 @name="Test Plugin", @description="Just a simple test plugin.", @version="1.0">> 
plugin_cleanup.info.name
 #=> "Test Plugin"
plugin_cleanup.info.name = "A New Plugin"
 #=> "A New Plugin"
plugin_cleanup.info.name
 #=> "A New Plugin"

answered Apr 28, 2011 at 6:13

PreciousBodilyFluids

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2 Comments

zetetic Over a year ago

Good application for namespacing: Plugin and Plugin::Info

Devin M Over a year ago

Hmm that looks good, I'm going to try and see if I can use namespacing like zetetic said.

Andrew Grimm · Accepted Answer · 2011-04-28 23:08:06Z

0

I think using instance_eval may help, like in the following example

class Panda
  def self.feed(&block)
    panda = Panda.new
    panda.instance_eval(&block)
  end

  def nom(food)
    puts "nomming #{food}"
  end
end

Panda.feed do
  nom :bamboo
  nom :chocolate
end

You'll have to adapt it a bit to your needs, but I'm just indicating that it's possible to do it. Let me know if you get stuck.

answered Apr 28, 2011 at 23:08

Andrew Grimm

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