зеркало из https://github.com/github/ruby.git
309 строки
8.5 KiB
Ruby
309 строки
8.5 KiB
Ruby
# frozen_string_literal: false
|
|
#
|
|
# forwardable.rb -
|
|
# $Release Version: 1.1$
|
|
# $Revision$
|
|
# by Keiju ISHITSUKA(keiju@ishitsuka.com)
|
|
# original definition by delegator.rb
|
|
# Revised by Daniel J. Berger with suggestions from Florian Gross.
|
|
#
|
|
# Documentation by James Edward Gray II and Gavin Sinclair
|
|
|
|
|
|
|
|
# The Forwardable module provides delegation of specified
|
|
# methods to a designated object, using the methods #def_delegator
|
|
# and #def_delegators.
|
|
#
|
|
# For example, say you have a class RecordCollection which
|
|
# contains an array <tt>@records</tt>. You could provide the lookup method
|
|
# #record_number(), which simply calls #[] on the <tt>@records</tt>
|
|
# array, like this:
|
|
#
|
|
# require 'forwardable'
|
|
#
|
|
# class RecordCollection
|
|
# attr_accessor :records
|
|
# extend Forwardable
|
|
# def_delegator :@records, :[], :record_number
|
|
# end
|
|
#
|
|
# We can use the lookup method like so:
|
|
#
|
|
# r = RecordCollection.new
|
|
# r.records = [4,5,6]
|
|
# r.record_number(0) # => 4
|
|
#
|
|
# Further, if you wish to provide the methods #size, #<<, and #map,
|
|
# all of which delegate to @records, this is how you can do it:
|
|
#
|
|
# class RecordCollection # re-open RecordCollection class
|
|
# def_delegators :@records, :size, :<<, :map
|
|
# end
|
|
#
|
|
# r = RecordCollection.new
|
|
# r.records = [1,2,3]
|
|
# r.record_number(0) # => 1
|
|
# r.size # => 3
|
|
# r << 4 # => [1, 2, 3, 4]
|
|
# r.map { |x| x * 2 } # => [2, 4, 6, 8]
|
|
#
|
|
# You can even extend regular objects with Forwardable.
|
|
#
|
|
# my_hash = Hash.new
|
|
# my_hash.extend Forwardable # prepare object for delegation
|
|
# my_hash.def_delegator "STDOUT", "puts" # add delegation for STDOUT.puts()
|
|
# my_hash.puts "Howdy!"
|
|
#
|
|
# == Another example
|
|
#
|
|
# We want to rely on what has come before obviously, but with delegation we can
|
|
# take just the methods we need and even rename them as appropriate. In many
|
|
# cases this is preferable to inheritance, which gives us the entire old
|
|
# interface, even if much of it isn't needed.
|
|
#
|
|
# class Queue
|
|
# extend Forwardable
|
|
#
|
|
# def initialize
|
|
# @q = [ ] # prepare delegate object
|
|
# end
|
|
#
|
|
# # setup preferred interface, enq() and deq()...
|
|
# def_delegator :@q, :push, :enq
|
|
# def_delegator :@q, :shift, :deq
|
|
#
|
|
# # support some general Array methods that fit Queues well
|
|
# def_delegators :@q, :clear, :first, :push, :shift, :size
|
|
# end
|
|
#
|
|
# q = Queue.new
|
|
# q.enq 1, 2, 3, 4, 5
|
|
# q.push 6
|
|
#
|
|
# q.shift # => 1
|
|
# while q.size > 0
|
|
# puts q.deq
|
|
# end
|
|
#
|
|
# q.enq "Ruby", "Perl", "Python"
|
|
# puts q.first
|
|
# q.clear
|
|
# puts q.first
|
|
#
|
|
# This should output:
|
|
#
|
|
# 2
|
|
# 3
|
|
# 4
|
|
# 5
|
|
# 6
|
|
# Ruby
|
|
# nil
|
|
#
|
|
# == Notes
|
|
#
|
|
# Be advised, RDoc will not detect delegated methods.
|
|
#
|
|
# +forwardable.rb+ provides single-method delegation via the def_delegator and
|
|
# def_delegators methods. For full-class delegation via DelegateClass, see
|
|
# +delegate.rb+.
|
|
#
|
|
module Forwardable
|
|
require 'forwardable/impl'
|
|
|
|
# Version of +forwardable.rb+
|
|
FORWARDABLE_VERSION = "1.2.0"
|
|
|
|
@debug = nil
|
|
class << self
|
|
# ignored
|
|
attr_accessor :debug
|
|
end
|
|
|
|
# Takes a hash as its argument. The key is a symbol or an array of
|
|
# symbols. These symbols correspond to method names. The value is
|
|
# the accessor to which the methods will be delegated.
|
|
#
|
|
# :call-seq:
|
|
# delegate method => accessor
|
|
# delegate [method, method, ...] => accessor
|
|
#
|
|
def instance_delegate(hash)
|
|
hash.each do |methods, accessor|
|
|
unless defined?(methods.each)
|
|
def_instance_delegator(accessor, methods)
|
|
else
|
|
methods.each {|method| def_instance_delegator(accessor, method)}
|
|
end
|
|
end
|
|
end
|
|
|
|
#
|
|
# Shortcut for defining multiple delegator methods, but with no
|
|
# provision for using a different name. The following two code
|
|
# samples have the same effect:
|
|
#
|
|
# def_delegators :@records, :size, :<<, :map
|
|
#
|
|
# def_delegator :@records, :size
|
|
# def_delegator :@records, :<<
|
|
# def_delegator :@records, :map
|
|
#
|
|
def def_instance_delegators(accessor, *methods)
|
|
methods.delete("__send__")
|
|
methods.delete("__id__")
|
|
for method in methods
|
|
def_instance_delegator(accessor, method)
|
|
end
|
|
end
|
|
|
|
# Define +method+ as delegator instance method with an optional
|
|
# alias name +ali+. Method calls to +ali+ will be delegated to
|
|
# +accessor.method+.
|
|
#
|
|
# class MyQueue
|
|
# extend Forwardable
|
|
# attr_reader :queue
|
|
# def initialize
|
|
# @queue = []
|
|
# end
|
|
#
|
|
# def_delegator :@queue, :push, :mypush
|
|
# end
|
|
#
|
|
# q = MyQueue.new
|
|
# q.mypush 42
|
|
# q.queue #=> [42]
|
|
# q.push 23 #=> NoMethodError
|
|
#
|
|
def def_instance_delegator(accessor, method, ali = method)
|
|
gen = Forwardable._delegator_method(self, accessor, method, ali)
|
|
|
|
# If it's not a class or module, it's an instance
|
|
(Module === self ? self : singleton_class).module_eval(&gen)
|
|
end
|
|
|
|
alias delegate instance_delegate
|
|
alias def_delegators def_instance_delegators
|
|
alias def_delegator def_instance_delegator
|
|
|
|
# :nodoc:
|
|
def self._delegator_method(obj, accessor, method, ali)
|
|
accessor = accessor.to_s unless Symbol === accessor
|
|
|
|
if Module === obj ?
|
|
obj.method_defined?(accessor) || obj.private_method_defined?(accessor) :
|
|
obj.respond_to?(accessor, true)
|
|
accessor = "#{accessor}()"
|
|
end
|
|
|
|
method_call = ".__send__(:#{method}, *args, &block)"
|
|
if _valid_method?(method)
|
|
loc, = caller_locations(2,1)
|
|
pre = "_ ="
|
|
mesg = "#{Module === obj ? obj : obj.class}\##{ali} at #{loc.path}:#{loc.lineno} forwarding to private method "
|
|
method_call = "#{<<-"begin;"}\n#{<<-"end;".chomp}"
|
|
begin;
|
|
unless defined? _.#{method}
|
|
::Kernel.warn "\#{caller_locations(1)[0]}: "#{mesg.dump}"\#{_.class}"'##{method}'
|
|
_#{method_call}
|
|
else
|
|
_.#{method}(*args, &block)
|
|
end
|
|
end;
|
|
end
|
|
|
|
_compile_method("#{<<-"begin;"}\n#{<<-"end;"}", __FILE__, __LINE__+1)
|
|
begin;
|
|
proc do
|
|
def #{ali}(*args, &block)
|
|
#{pre}
|
|
begin
|
|
#{accessor}
|
|
end#{method_call}#{FILTER_EXCEPTION}
|
|
end
|
|
end
|
|
end;
|
|
end
|
|
end
|
|
|
|
# SingleForwardable can be used to setup delegation at the object level as well.
|
|
#
|
|
# printer = String.new
|
|
# printer.extend SingleForwardable # prepare object for delegation
|
|
# printer.def_delegator "STDOUT", "puts" # add delegation for STDOUT.puts()
|
|
# printer.puts "Howdy!"
|
|
#
|
|
# Also, SingleForwardable can be used to set up delegation for a Class or Module.
|
|
#
|
|
# class Implementation
|
|
# def self.service
|
|
# puts "serviced!"
|
|
# end
|
|
# end
|
|
#
|
|
# module Facade
|
|
# extend SingleForwardable
|
|
# def_delegator :Implementation, :service
|
|
# end
|
|
#
|
|
# Facade.service #=> serviced!
|
|
#
|
|
# If you want to use both Forwardable and SingleForwardable, you can
|
|
# use methods def_instance_delegator and def_single_delegator, etc.
|
|
module SingleForwardable
|
|
# Takes a hash as its argument. The key is a symbol or an array of
|
|
# symbols. These symbols correspond to method names. The value is
|
|
# the accessor to which the methods will be delegated.
|
|
#
|
|
# :call-seq:
|
|
# delegate method => accessor
|
|
# delegate [method, method, ...] => accessor
|
|
#
|
|
def single_delegate(hash)
|
|
hash.each do |methods, accessor|
|
|
unless defined?(methods.each)
|
|
def_single_delegator(accessor, methods)
|
|
else
|
|
methods.each {|method| def_single_delegator(accessor, method)}
|
|
end
|
|
end
|
|
end
|
|
|
|
#
|
|
# Shortcut for defining multiple delegator methods, but with no
|
|
# provision for using a different name. The following two code
|
|
# samples have the same effect:
|
|
#
|
|
# def_delegators :@records, :size, :<<, :map
|
|
#
|
|
# def_delegator :@records, :size
|
|
# def_delegator :@records, :<<
|
|
# def_delegator :@records, :map
|
|
#
|
|
def def_single_delegators(accessor, *methods)
|
|
methods.delete("__send__")
|
|
methods.delete("__id__")
|
|
for method in methods
|
|
def_single_delegator(accessor, method)
|
|
end
|
|
end
|
|
|
|
# :call-seq:
|
|
# def_single_delegator(accessor, method, new_name=method)
|
|
#
|
|
# Defines a method _method_ which delegates to _accessor_ (i.e. it calls
|
|
# the method of the same name in _accessor_). If _new_name_ is
|
|
# provided, it is used as the name for the delegate method.
|
|
def def_single_delegator(accessor, method, ali = method)
|
|
gen = Forwardable._delegator_method(self, accessor, method, ali)
|
|
|
|
instance_eval(&gen)
|
|
end
|
|
|
|
alias delegate single_delegate
|
|
alias def_delegators def_single_delegators
|
|
alias def_delegator def_single_delegator
|
|
end
|