config_file.rb

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#!/usr/bin/env ruby
#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++


require 'yaml'

module Gem

  ####################################################################
  # Store the gem command options specified in the configuration file.
  # The config file object acts much like a hash.
  #
  class ConfigFile
    # True if the backtrace option has been specified.
    attr_reader :backtrace
    
    # List of arguments supplied to the config file object.
    attr_reader :args

    # Verbose level of output:
    # * false -- No output
    # * true -- Normal output
    # * :loud -- Extra output
    attr_accessor :verbose

    # Create the config file object.  +args+ is the list of arguments
    # from the command line.
    #
    # The following command line options are handled early here rather
    # than later at the time most command options are processed.
    #
    # * --config-file and --config-file==NAME -- Obviously these need
    #   to be handled by the ConfigFile object to ensure we get the
    #   right config file.
    #   
    # * --backtrace -- Backtrace needs to be turned on early so that
    #   errors before normal option parsing can be properly handled.
    #
    # * --debug -- Enable Ruby level debug messages.  Handled early
    #   for the same reason as --backtrace.
    #
    def initialize(arg_list)
      @verbose = true
      handle_arguments(arg_list)
      begin
        @hash = open(config_file_name) {|f| YAML.load(f) }
      rescue ArgumentError
        warn "Failed to load #{config_file_name}"
      rescue Errno::ENOENT
        # Ignore missing config file error.
      rescue Errno::EACCES                 
        warn "Failed to load #{config_file_name} due to permissions problem."
      end
      @hash ||= {}
    end

    # The name of the configuration file.
    def config_file_name
      @config_file_name || Gem.config_file
    end

    # Return the configuration information for +key+.
    def [](key)
      @hash[key.to_s]
    end

    private

    # Handle the command arguments.
    def handle_arguments(arg_list)
      need_cfg_name = false
      @args = []
      arg_list.each do |arg|
	if need_cfg_name
	  @config_file_name = arg
	  need_cfg_name = false
	else
	  case arg
	  when /^--(traceback|backtrace)$/
	    @backtrace = true
          when /^--debug$/
            $DEBUG = true
	  when /^--config-file$/
	    need_cfg_name = true
	  when /^--config-file=(.+)$/
	    @config_file_name = $1
	  else
	    @args << arg
	  end
	end
      end
    end
  end

end