ConfigLeaf

ConfigLeaf allows an object to be configured using a terse syntax like Object#instance_eval, while not exposing the internals (protected/private methods and ivars) of the object!

If the user doesn't like to use this ConfigLeaf wrapping, then they can just use normal #tap syntax by requesting a block parameter.

Installation

Add this line to your application's Gemfile:

gem 'config_leaf'

And then execute:

$ bundle

Or install it yourself as:

$ gem install config_leaf

Usage

ConfigLeaf can be used directly by the end-user after an object has been created, but it more likely used by those wanting to allow block setting of config after their object has been instantiated:

require 'config_leaf'

class Cheese
  attr_accessor :value, :list

  def initialize(&block)
    # Set defaults.
    @value = 0
    @list = []

    # Allow the user access via ConfigLeaf syntax.
    ConfigLeaf.wrap self, &block if block_given?
  end

  def reverse!
    @list.reverse!
  end

  protected
  def explode!
    DeathStar.instance.boom!
  end
end

# User uses the ConfigLeaf block syntax.
object1 = Cheese.new do
  list [1, 2, 3]      # Calls object.list = [1, 2, 3]
  list << 4           # Calls object.list << 4
  value 5             # Calls object.value = 5
  value list.size     # Calls object.value = object.list.size
  reverse!            # Calls object.reverse!

  ## @value = 99      # Would set @value on the wrapper, not in the wrapped object, so raises an exception.

  ## explode!         # Not allowed because it is protected (raises an exception).
end

# User chooses to not use ConfigLeaf block syntax by requesting a block parameter.
object2 = Cheese.new do |c|
  c.list = [1, 2, 3]
  c.list << 4
  c.value = 5
  c.value = c.list.size
  c.reverse!
end

p object1 #=> #<Cheese:0x4340658 @value=4, @list=[4, 3, 2, 1]>
p object2 #=> #<Cheese:0x45d2b58 @value=4, @list=[4, 3, 2, 1]>

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Added some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request