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require 'tsort'
module Rails
module Initializable
def self.included(base)
base.extend ClassMethods
end
class Initializer
attr_reader :name, :block
def initialize(name, context, options, &block)
options[:group] ||= :default
@name, @context, @options, @block = name, context, options, block
end
def before
@options[:before]
end
def after
@options[:after]
end
def belongs_to?(group)
@options[:group] == group || @options[:group] == :all
end
def run(*args)
@context.instance_exec(*args, &block)
end
def bind(context)
return self if @context
Initializer.new(@name, context, @options, &block)
end
end
class Collection < Array
include TSort
alias :tsort_each_node :each
def tsort_each_child(initializer, &block)
select { |i| i.before == initializer.name || i.name == initializer.after }.each(&block)
end
def +(other)
Collection.new(to_a + other.to_a)
end
end
def run_initializers(group=:default, *args)
return if instance_variable_defined?(:@ran)
initializers.tsort_each do |initializer|
initializer.run(*args) if initializer.belongs_to?(group)
end
@ran = true
end
def initializers
@initializers ||= self.class.initializers_for(self)
end
module ClassMethods
def initializers
@initializers ||= Collection.new
end
def initializers_chain
initializers = Collection.new
ancestors.reverse_each do |klass|
next unless klass.respond_to?(:initializers)
initializers = initializers + klass.initializers
end
initializers
end
def initializers_for(binding)
Collection.new(initializers_chain.map { |i| i.bind(binding) })
end
def initializer(name, opts = {}, &blk)
raise ArgumentError, "A block must be passed when defining an initializer" unless blk
opts[:after] ||= initializers.last.name unless initializers.empty? || initializers.find { |i| i.name == opts[:before] }
initializers << Initializer.new(name, nil, opts, &blk)
end
end
end
end
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