diff options
Diffstat (limited to 'lib/forwardable.rb')
| -rw-r--r-- | lib/forwardable.rb | 175 |
1 files changed, 106 insertions, 69 deletions
diff --git a/lib/forwardable.rb b/lib/forwardable.rb index d7116ed1bc..175d6d9c6b 100644 --- a/lib/forwardable.rb +++ b/lib/forwardable.rb @@ -1,3 +1,4 @@ +# frozen_string_literal: false # # forwardable.rb - # $Release Version: 1.1$ @@ -19,37 +20,46 @@ # #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 -# # extend Forwardable, but we did that above +# class RecordCollection # re-open RecordCollection class # def_delegators :@records, :size, :<<, :map # end -# f = Foo.new -# f.printf ... -# f.gets -# f.content_at(1) # -# If the object isn't a Module and Class, You can too extend Forwardable -# module. +# 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] # -# printer = String.new -# printer.extend Forwardable # prepare object for delegation -# printer.def_delegator "STDOUT", "puts" # add delegation for STDOUT.puts() -# printer.puts "Howdy!" +# 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. +# You could use Forwardable as an alternative to inheritance, when you don't want +# to inherit all methods from the superclass. For instance, here is how you might +# add a range of +Array+ instance methods to a new class +Queue+: # # class Queue # extend Forwardable @@ -66,7 +76,7 @@ # def_delegators :@q, :clear, :first, :push, :shift, :size # end # -# q = Queue.new +# q = Thread::Queue.new # q.enq 1, 2, 3, 4, 5 # q.push 6 # @@ -100,17 +110,22 @@ # module Forwardable # Version of +forwardable.rb+ - FORWARDABLE_VERSION = "1.1.0" + VERSION = "1.4.0" + VERSION.freeze + + # Version for backward compatibility + FORWARDABLE_VERSION = VERSION + FORWARDABLE_VERSION.freeze @debug = nil class << self - # If true, <tt>__FILE__</tt> will remain in the backtrace in the event an - # Exception is raised. + # 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 + # symbols. These symbols correspond to method names, instance variable + # names, or constant names (see def_delegator). The value is # the accessor to which the methods will be delegated. # # :call-seq: @@ -118,12 +133,13 @@ module Forwardable # delegate [method, method, ...] => accessor # def instance_delegate(hash) - hash.each{ |methods, accessor| - methods = [methods] unless methods.respond_to?(:each) - methods.each{ |method| - def_instance_delegator(accessor, method) - } - } + 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 # @@ -138,18 +154,21 @@ module Forwardable # def_delegator :@records, :map # def def_instance_delegators(accessor, *methods) - methods.delete("__send__") - methods.delete("__id__") - for method in methods + methods.each do |method| + next if /\A__(?:send|id)__\z/ =~ method 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+. + # +accessor.method+. +accessor+ should be a method name, instance + # variable name, or constant name. Use the full path to the + # constant if providing the constant name. + # Returns the name of the method defined. # # class MyQueue + # CONST = 1 # extend Forwardable # attr_reader :queue # def initialize @@ -157,36 +176,62 @@ module Forwardable # end # # def_delegator :@queue, :push, :mypush + # def_delegator 'MyQueue::CONST', :to_i # end # # q = MyQueue.new # q.mypush 42 # q.queue #=> [42] # q.push 23 #=> NoMethodError + # q.to_i #=> 1 # def def_instance_delegator(accessor, method, ali = method) - line_no = __LINE__; str = %{ - def #{ali}(*args, &block) - begin - #{accessor}.__send__(:#{method}, *args, &block) - rescue Exception - $@.delete_if{|s| %r"#{Regexp.quote(__FILE__)}"o =~ s} unless Forwardable::debug - ::Kernel::raise - end - end - } - # If it's not a class or module, it's an instance - begin - module_eval(str, __FILE__, line_no) - rescue - instance_eval(str, __FILE__, line_no) - end + gen = Forwardable._delegator_method(self, accessor, method, ali) + # If it's not a class or module, it's an instance + mod = Module === self ? self : singleton_class + mod.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 + + args = RUBY_VERSION >= '2.7' ? '...' : '*args, &block' + method_call = ".__send__(:#{method}, #{args})" + if method.match?(/\A[_a-zA-Z]\w*[?!]?\z/) + loc, = caller_locations(2,1) + pre = "_ =" + mesg = "#{Module === obj ? obj : obj.class}\##{ali} at #{loc.path}:#{loc.lineno} forwarding to private method " + method_call = <<~RUBY.chomp + if defined?(_.#{method}) + _.#{method}(#{args}) + else + ::Kernel.warn #{mesg.dump}"\#{_.class}"'##{method}', uplevel: 1 + _#{method_call} + end + RUBY + end + + eval(<<~RUBY, nil, __FILE__, __LINE__ + 1) + proc do + def #{ali}(#{args}) + #{pre}#{accessor} + #{method_call} + end + end + RUBY + end end # SingleForwardable can be used to setup delegation at the object level as well. @@ -203,14 +248,14 @@ end # 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 @@ -223,12 +268,13 @@ module SingleForwardable # delegate [method, method, ...] => accessor # def single_delegate(hash) - hash.each{ |methods, accessor| - methods = [methods] unless methods.respond_to?(:each) - methods.each{ |method| - def_single_delegator(accessor, method) - } - } + 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 # @@ -243,9 +289,8 @@ module SingleForwardable # def_delegator :@records, :map # def def_single_delegators(accessor, *methods) - methods.delete("__send__") - methods.delete("__id__") - for method in methods + methods.each do |method| + next if /\A__(?:send|id)__\z/ =~ method def_single_delegator(accessor, method) end end @@ -256,19 +301,11 @@ module SingleForwardable # 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. + # Returns the name of the method defined. def def_single_delegator(accessor, method, ali = method) - str = %{ - def #{ali}(*args, &block) - begin - #{accessor}.__send__(:#{method}, *args, &block) - rescue Exception - $@.delete_if{|s| %r"#{Regexp.quote(__FILE__)}"o =~ s} unless Forwardable::debug - ::Kernel::raise - end - end - } + gen = Forwardable._delegator_method(self, accessor, method, ali) - instance_eval(str, __FILE__, __LINE__) + instance_eval(&gen) end alias delegate single_delegate |