class ImportError < Exception; end
module Kernel
# abstraction:: only include the methods given by _meths_
# implementation:: includes a duplicate of _mod_ with only the specified instance methods included. By default, all private methods will be included unless the option :import_private is set to false. If no methods are given,
def import(mod, *methods_or_options)
mod_dup = mod.dup
unless methods_or_options.empty?
# get list of methods to remove module
ims = mod.instance_methods
meths = []
modifiers = []
methods_or_options.each do |m_o|
case m_o
when Hash
bool = m_o.delete(:import_private)
if bool.nil?
modifiers.push m_o
else
if meths.empty? and methods_or_options.size == 1 and m_o.empty?
fail ArgumentError,
"methods arguments required with :import_private flag"
end
if bool == false
ims += mod.private_instance_methods
end
end
else
meths.push m_o
end
end
ims.map! {|m| m.to_sym}
removes = ims - meths
if removes.size != (ims.size - meths.size)
raise ImportError,
"##{(meths - ims).join(' and #')} not found in #{mod}"
end
mod_dup.module_eval do
keeps = []
modifiers.each do |hash|
hash.each_pair do |meths, modifier|
meths = meths.is_a?(Array) ? meths : [meths]
case modifier
when :as_public
public *meths
keeps.concat meths
when :as_private
private *meths
keeps.concat meths
else # don't keep renamed methods
unless meths.size == 1
fail ArgumentError, "cannot alias multiple methods to the same alias"
end
m = modifier.to_s
unless m[0..2] == 'as_' && m[3]
raise ArgumentError, "expected as_ modifier"
end
alias_method :"#{m[3..-1]}", meths.first
end
end
end
(removes - keeps).each { |meth| remove_method meth }
end
end
include mod_dup
end
end
