lib/observed/config_dsl.rb
require 'observed/observer'
require 'observed/configurable'
require 'forwardable'
require 'logger'
module Observed
# The DSL to describe Observed's configuration.
# @example
# context = ConfigDSL.new(builder: the_builder)
# context.eval_file observed_conf_file(a.k.a user code describes Observed configuration)
# context.config #=> can be used to instantiate Observed::System
class ConfigDSL
extend Forwardable
include Observed::Configurable
def_delegators :@builder, :observe, :translate, :report, :read, :write, :emit, :group, :run_group, :receive
attribute :builder
attribute :logger, default: Logger.new(STDOUT)
def initialize(args)
args[:builder] || fail("The key :builder must exist in #{args}")
@builder = args[:builder]
configure(args)
end
def eval_file(file)
@file = File.expand_path(file)
working_directory File.dirname(@file)
logger.debug "Reading the file: #{@file}"
code = File.read(@file)
logger.debug "Evaluating: #{code}"
instance_eval(code, @file)
end
# The `current directory` in which `require_relative` finds source files
def working_directory(wd=nil)
@working_directory = wd if wd
@working_directory
end
# The replacement for Ruby's built-in `require_relative`.
# Although the built-in one can not be used in `eval` or `instance_eval` or etc because
# there is no `current file` semantics in `eval`, this replacement takes the file which is going to be evaluated
# as the `current file`.
# Thanks to this method, we can use `require_relative` in observed.conf files both when it is evaluated with `eval`
# and when it is evaluated in result of `require`.
def require_relative(lib)
path = File.expand_path("#{working_directory}/#{lib}")
logger.debug "Require '#{path}'"
require path
end
# Build and returns the Observed configuration
# @return [Observed::Config]
def config
@builder.build
end
# Load the file and evaluate the containing code in context of this object(a.k.a DSL).
# @param [String|Pathname] file The path to Ruby script containing the code in Observed's configuration DSL,
# typically `observed.conf`.
def load!(file)
eval_file file
end
end
end