Improving handling of reserved names in OpenStruct

[Akinori_MUSHA]

　OpenStruct の実装を何点か改善したいと考えています。

1. [ruby-dev:40463]のような respond_to? の挙動に依存した部分は
   書き換えたい。protected メソッドと同名のメンバーは従来通り
   使用可能に。

2. new_ostruct_member など、 OpenStruct の実装に使われている
   public メソッドと同名のメンバーを作ろうとしても、値を取り
   出そうとすれば予期せぬメソッドが呼ばれ、また仮に代入できて
   しまうとすれば誤動作を招くのだから、 NameError を出すべき
   ではないだろうか。

   ただ、無視してくれた方が不定データを取り込む際には便利かも
   しれないので、明示的にチェックの有無を指定させる方がよい？
   たとえば OpenStruct.new(hash, validate = false) とフラグを
   åŠ ãˆã‚‹ãªã©ã€‚

3. class や method などの Kernel モジュールメソッドと同名の
   メンバーは、ユーザが望むなら使えるべきではないか。

　関心のある方は意見をください。

　とりあえず上記の基本部分をひとまとめにしたパッチを付けます。

–
Akinori MUSHA / http://akinori.org/

Index: lib/ostruct.rb

— lib/ostruct.rb (revision 26742)
+++ lib/ostruct.rb (working copy)
@@ -31,6 +31,11 @@

p data # → <OpenStruct country=“Australia”

population=20000000>

class OpenStruct

• METHOD_class = Kernel.instance_method(:class)
• METHOD_object_id = Kernel.instance_method(:object_id)
• METHOD_method = Kernel.instance_method(:method)
• METHOD_public_method = Kernel.instance_method(:public_method)

• Create a new OpenStruct object. The optional +hash+, if given,

will

generate attributes and values. For example.

@@ -79,12 +84,25 @@ class OpenStruct

def new_ostruct_member(name)
name = name.to_sym

• unless self.respond_to?(name)

•  class << self; self; end.class_eval do
  

•    define_method(name) { @table[name] }
  

•    define_method("#{name}=") { |x| modifiable[name] = x }
  

• singleton = class << self; self; end
• if self.respond_to?(name)

•  protected_p = false
  

•  begin
  

•    owner = METHOD_public_method.bind(self).call(name).owner
  

•  rescue NameError
  

•    owner = METHOD_method.bind(self).call(name).owner
  

•    protected_p = true
  

•  end
  

•  if owner == singleton || protected_p
  

•    return name
  

•  elsif owner <= OpenStruct
  

•    raise NameError, "the name `#{name}' is reserved by 
  

implementation (#{owner})"
end
end

• singleton.class_eval do

•  define_method(name) { @table[name] }
  

•  define_method("#{name}=") { |x| modifiable[name] = x }
  

• end
  name
  end

@@ -116,14 +134,14 @@ class OpenStruct

Returns a string containing a detailed summary of the keys and

values.

def inspect

• str = “#<#{self.class}”

• str = “#<#{METHOD_class.bind(self).call}”

  ids = (Thread.current[InspectKey] ||= [])
  if ids.include?(object_id)
  return str << ’ …>’
  end

• ids << object_id

• ids << METHOD_object_id.bind(self).call
  begin
  first = true
  for k,v in @table
  Index: test/ostruct/test_ostruct.rb
  ===================================================================
  — test/ostruct/test_ostruct.rb (revision 26742)
  +++ test/ostruct/test_ostruct.rb (working copy)
  @@ -21,6 +21,47 @@ class TC_OpenStruct < Test::Unit::TestCa
  assert_not_equal(o1, o2)
  end

• def test_kernel_methods

• o = OpenStruct.new

• assert_nothing_raised(“The name ‘method’ should be available”) {

•  o.method = :something
  

•  assert_equal(:something, o.method)
  

• }

• o = OpenStruct.new

• o.object_id = 123

• o.class = “Foo”

• assert_equal(“#<OpenStruct object_id=123, class="Foo">”,
  o.inspect,

•  "Setting 'class' should not affect the result of #inspect")
  

• end

• def test_protected_methods

• o = OpenStruct.new

• assert_nothing_raised(“The name ‘modifiable’ should be available”)
  {

•  o.modifiable = :something
  

•  assert_equal(:something, o.modifiable)
  

• }

• assert_nothing_raised(“The name ‘table’ should be available”) {

•  o.table = :something
  

•  assert_equal(:something, o.table)
  

• }

• end

• def test_reserved_methods

• assert_raises(NameError) {

•  o = OpenStruct.new
  

•  o.inspect = "foo"
  

• }

• assert_raises(NameError) {

•  subclass = Class.new(OpenStruct)
  

•  o = subclass.new
  

•  o.inspect = "foo"
  

• }

• end

• def test_inspect
  foo = OpenStruct.new
  assert_equal(“#”, foo.inspect)