25 September 2013
Rubyでオブジェクトの特徴的なメソッドを知りたい
オブジェクトがどんな挙動をするのか、つまりそのオブジェクトの特徴的なメソッド群をさっと知りたいとします。そんなとき自分はObject#methodsを呼びます。
irb> [1,2,3].methods
=> [:inspect, :to_s, :to_a, :to_ary, :frozen?, :==, :eql?, :hash, :[], :[]=, :at, :fetch, :first, :last, :concat, :<<, :push, :pop, :shift, :unshift, :insert, :each, :each_index, :reverse_each, :length, :size, :empty?, :find_index, :index, :rindex, :join, :reverse, :reverse!, :rotate, :rotate!, :sort, :sort!, :sort_by!, :collect, :collect!, :map, :map!, :select, :select!, :keep_if, :values_at, :delete, :delete_at, :delete_if, :reject, :reject!, :zip, :transpose, :replace, :clear, :fill, :include?, :<=>, :slice, :slice!, :assoc, :rassoc, :+, :*, :-, :&, :|, :uniq, :uniq!, :compact, :compact!, :flatten, :flatten!, :count, :shuffle!, :shuffle, :sample, :cycle, :permutation, :combination, :repeated_permutation, :repeated_combination, :product, :take, :take_while, :drop, :drop_while, :bsearch, :pack, :entries, :sort_by, :grep, :find, :detect, :find_all, :flat_map, :collect_concat, :inject, :reduce, :partition, :group_by, :all?, :any?, :one?, :none?, :min, :max, :minmax, :min_by, :max_by, :minmax_by, :member?, :each_with_index, :each_entry, :each_slice, :each_cons, :each_with_object, :chunk, :slice_before, :lazy, :nil?, :===, :=~, :!~, :class, :singleton_class, :clone, :dup, :taint, :tainted?, :untaint, :untrust, :untrusted?, :trust, :freeze, :methods, :singleton_methods, :protected_methods, :private_methods, :public_methods, :instance_variables, :instance_variable_get, :instance_variable_set, :instance_variable_defined?, :remove_instance_variable, :instance_of?, :kind_of?, :is_a?, :tap, :send, :public_send, :respond_to?, :extend, :display, :method, :public_method, :define_singleton_method, :object_id, :to_enum, :enum_for, :equal?, :!, :!=, :instance_eval, :instance_exec, :__send__, :__id__]しかし、この結果にはそのオブジェクトで利用できるすべてのメソッドが含まれているので、これを眺めてそのオブジェクトの特性を推測するのは困難です。
methodsメソッドの引数にfalseを渡すと、そのオブジェクト固有のメソッドだけが抽出されます。
irb> [1,2,3].methods(false)
=> []シングルトンメソッドが定義されていない限り、通常何も出力されないので、あまり役に立ちません。
そこで、そのオブジェクトのクラスを調べ、そのクラスに定義されているメソッドを調べることになります。
irb> [1,2,3].class
=> Array
irb> Array.instance_methods(false)
=> [:inspect, :to_s, :to_a, :to_ary, :frozen?, :==, :eql?, :hash, :[], :[]=, :at, :fetch, :first, :last, :concat, :<<, :push, :pop, :shift, :unshift, :insert, :each, :each_index, :reverse_each, :length, :size, :empty?, :find_index, :index, :rindex, :join, :reverse, :reverse!, :rotate, :rotate!, :sort, :sort!, :sort_by!, :collect, :collect!, :map, :map!, :select, :select!, :keep_if, :values_at, :delete, :delete_at, :delete_if, :reject, :reject!, :zip, :transpose, :replace, :clear, :fill, :include?, :<=>, :slice, :slice!, :assoc, :rassoc, :+, :*, :-, :&, :|, :uniq, :uniq!, :compact, :compact!, :flatten, :flatten!, :count, :shuffle!, :shuffle, :sample, :cycle, :permutation, :combination, :repeated_permutation, :repeated_combination, :product, :take, :take_while, :drop, :drop_while, :bsearch, :pack]もう一歩進んで、継承上位のクラスに特徴的なメソッド群がないか見たいこともあります。そんなときは、そのオブジェクトのクラス継承を調べて、メソッドを見つけることになります。
irb> [1,2,3].class.ancestors
=> [Array, Enumerable, Object, Kernel, BasicObject]
irb> Enumerable.instance_methods(false)
=> [:to_a, :entries, :sort, :sort_by, :grep, :count, :find, :detect, :find_index, :find_all, :select, :reject, :collect, :map, :flat_map, :collect_concat, :inject, :reduce, :partition, :group_by, :first, :all?, :any?, :one?, :none?, :min, :max, :minmax, :min_by, :max_by, :minmax_by, :member?, :include?, :each_with_index, :reverse_each, :each_entry, :each_slice, :each_cons, :each_with_object, :zip, :take, :take_while, :drop, :drop_while, :cycle, :chunk, :slice_before, :lazy]なんか…
面倒ですよね？
そんなわけで…Array#flattenに倣って…
Object#methodsが数字を取れるようにしてみましたよ！
module Skin
def methods(lv=true)
case lv
when Fixnum
return super(false) if lv<=0
self.class.ancestors.take(lv)
.map { |klass| klass.instance_methods(false) }
.inject { |acc, klass| acc | klass }
else
super
end
end
end
Object.send(:include, Skin)0はfalseと等価です。数字が増える度に継承上位のメソッド群が足されていきます。
irb> [1,2,3].methods(0)
=> []
irb> [1,2,3].methods(1)
=> [:inspect, :to_s, :to_a, :to_ary, :frozen?, :==, :eql?, :hash, :[], :[]=, :at, :fetch, :first, :last, :concat, :<<, :push, :pop, :shift, :unshift, :insert, :each, :each_index, :reverse_each, :length, :size, :empty?, :find_index, :index, :rindex, :join, :reverse, :reverse!, :rotate, :rotate!, :sort, :sort!, :sort_by!, :collect, :collect!, :map, :map!, :select, :select!, :keep_if, :values_at, :delete, :delete_at, :delete_if, :reject, :reject!, :zip, :transpose, :replace, :clear, :fill, :include?, :<=>, :slice, :slice!, :assoc, :rassoc, :+, :*, :-, :&, :|, :uniq, :uniq!, :compact, :compact!, :flatten, :flatten!, :count, :shuffle!, :shuffle, :sample, :cycle, :permutation, :combination, :repeated_permutation, :repeated_combination, :product, :take, :take_while, :drop, :drop_while, :bsearch, :pack]
irb> [1,2,3].methods(2)
=> [:inspect, :to_s, :to_a, :to_ary, :frozen?, :==, :eql?, :hash, :[], :[]=, :at, :fetch, :first, :last, :concat, :<<, :push, :pop, :shift, :unshift, :insert, :each, :each_index, :reverse_each, :length, :size, :empty?, :find_index, :index, :rindex, :join, :reverse, :reverse!, :rotate, :rotate!, :sort, :sort!, :sort_by!, :collect, :collect!, :map, :map!, :select, :select!, :keep_if, :values_at, :delete, :delete_at, :delete_if, :reject, :reject!, :zip, :transpose, :replace, :clear, :fill, :include?, :<=>, :slice, :slice!, :assoc, :rassoc, :+, :*, :-, :&, :|, :uniq, :uniq!, :compact, :compact!, :flatten, :flatten!, :count, :shuffle!, :shuffle, :sample, :cycle, :permutation, :combination, :repeated_permutation, :repeated_combination, :product, :take, :take_while, :drop, :drop_while, :bsearch, :pack, :entries, :sort_by, :grep, :find, :detect, :find_all, :flat_map, :collect_concat, :inject, :reduce, :partition, :group_by, :all?, :any?, :one?, :none?, :min, :max, :minmax, :min_by, :max_by, :minmax_by, :member?, :each_with_index, :each_entry, :each_slice, :each_cons, :each_with_object, :chunk, :slice_before, :lazy]
irb> [1,2,3].class.ancestors
=> [Array, Enumerable, Object, Skin, Kernel, BasicObject]
irb> [1,2,3].methods(0).size
=> 0
irb> [1,2,3].methods(1).size
=> 89
irb> [1,2,3].methods(2).size
=> 120
irb> [1,2,3].methods(3).size
=> 120
irb> [1,2,3].methods(4).size
=> 121
irb> [1,2,3].methods(5).size
=> 160
irb> [1,2,3].methods(6).size
=> 167
irb> [1,2,3].methods.size
=> 167Nokogiriでの結果はこんな感じです。
irb> require 'nokogiri'
=> true
irb> html = Nokogiri::HTML('<html></html>')
=> #<Nokogiri::HTML::Document:0x3fd0ea1d71d0 name="document" children=[#<Nokogiri::XML::DTD:0x3fd0ea1d6e38 name="html">, #<Nokogiri::XML::Element:0x3fd0ea1d6ab4 name="html">]>
irb> html.class.ancestors
=> [Nokogiri::HTML::Document, Nokogiri::XML::Document, Nokogiri::XML::Node, Enumerable, Nokogiri::XML::PP::Node, Object, Skin, Kernel, BasicObject]
irb> html.methods(0)
=> []
irb> html.methods(1)
=> [:type, :meta_encoding, :meta_encoding=, :title, :title=, :serialize, :fragment]
irb> html.methods(2)
=> [:type, :meta_encoding, :meta_encoding=, :title, :title=, :serialize, :fragment, :root, :root=, :encoding, :encoding=, :version, :canonicalize, :dup, :url, :create_entity, :remove_namespaces!, :errors, :errors=, :create_element, :create_text_node, :create_cdata, :create_comment, :name, :document, :collect_namespaces, :decorators, :validate, :slop!, :decorate, :to_xml, :clone, :namespaces, :add_child, :<<, :to_java]
irb> html.methods(3)
=> [:type, :meta_encoding, :meta_encoding=, :title, :title=, :serialize, :fragment, :root, :root=, :encoding, :encoding=, :version, :canonicalize, :dup, :url, :create_entity, :remove_namespaces!, :errors, :errors=, :create_element, :create_text_node, :create_cdata, :create_comment, :name, :document, :collect_namespaces, :decorators, :validate, :slop!, :decorate, :to_xml, :clone, :namespaces, :add_child, :<<, :to_java, :add_namespace_definition, :node_name, :node_name=, :parent, :child, :first_element_child, :last_element_child,
:children, :element_children, :next_sibling, :previous_sibling, :next_element, :previous_element, :node_type, :content, :path, :key?, :namespaced_key?, :blank?, :attribute_nodes,
:attribute, :attribute_with_ns, :namespace, :namespace_definitions, :namespace_scopes, :encode_special_chars, :unlink, :internal_subset, :external_subset, :create_internal_subse
t, :create_external_subset, :pointer_id, :line, :native_content=, :decorate!, :search, :/, :xpath, :css, :>, :at, :%, :at_xpath, :at_css, :[], :[]=, :add_previous_sibling, :add_n
ext_sibling, :before, :after, :inner_html=, :children=, :replace, :swap, :next, :previous, :next=, :previous=, :remove, :get_attribute, :attr, :set_attribute, :text, :inner_text,
:has_attribute?, :name=, :to_str, :elements, :attributes, :values, :keys, :each, :remove_attribute, :delete, :matches?, :parse, :content=, :parent=, :comment?, :cdata?, :xml?, :
html?, :text?, :fragment?, :description, :read_only?, :element?, :elem?, :to_s, :inner_html, :css_path, :ancestors, :default_namespace=, :add_namespace, :namespace=, :traverse, :
accept, :==, :to_html, :to_xhtml, :write_to, :write_html_to, :write_xhtml_to, :write_xml_to, :<=>, :do_xinclude]
irb> html.methods(3).size
=> 142
irb> html.methods(4).size
=> 190
irb> html.methods(5).size
=> 192
irb> html.methods.size
=> 231どうでしょうか。って、お前の分別はどうしたって話ですけど。
そういえば、Object.methodsの引数ってどんなオブジェクトも受けるんですねー。false, nil以外は全部trueと解釈されますね。
(追記：2013-09-26)
Twitterで@niku_nameさんに、obj.public_methods(false)を教えて頂きました。これはobjにシングルトンメソッドが定義されていなければ、obj.class.instance_methods(false)と同じになります。
(追記：2013-09-26)
Twitterで@mad_pさんに、pryでcdしてlsする方法を教えて頂きました。
nokogiriの例で見てみます。cd [obj] => lsとせずに、ls [obj]としてもいいのですね。モジュール別にメソッドがリスティングされるので、これは見やすくて便利！
[1] pry(main)> html = Nokogiri::HTML('<html></html>')
=> #(Document:0x3fe855ebaa3c {
name = "document",
children = [
#(DTD:0x3fe855eba0c8 { name = "html" }),
#(Element:0x3fe855ebfb18 { name = "html" })]
})
[2] pry(main)> html.class.ancestors
=> [Nokogiri::HTML::Document,
Nokogiri::XML::Document,
Nokogiri::XML::Node,
Enumerable,
Nokogiri::XML::PP::Node,
Object,
PP::ObjectMixin,
Kernel,
BasicObject]
[3] pry(#<Nokogiri::HTML::Document>):1> ls html
Nokogiri::XML::PP::Node#methods: inspect pretty_print
Enumerable#methods:
all? each_cons flat_map min select
any? each_entry grep min_by slice_before
chunk each_slice group_by minmax sort
collect each_with_index include? minmax_by sort_by
collect_concat each_with_object inject none? take
count entries lazy one? take_while
cycle find map partition to_a
detect find_all max reduce zip
drop find_index max_by reject
drop_while first member? reverse_each
Nokogiri::XML::Node#methods:
% delete node_name=
/ description node_type
<=> do_xinclude parent=
== each parse
> elem? path
[] element? pointer_id
[]= element_children previous
accept elements previous=
add_next_sibling encode_special_chars previous_element
add_previous_sibling external_subset previous_sibling
after first_element_child read_only?
ancestors fragment? remove
at get_attribute remove_attribute
at_css has_attribute? replace
at_xpath html? search
attr inner_html set_attribute
attribute inner_html= text
attribute_nodes inner_text text?
attribute_with_ns internal_subset to_html
before key? to_s
blank? keys to_str
cdata? last_element_child to_xhtml
child matches? traverse
children name= unlink
children= namespace= values
comment? namespace_scopes write_html_to
content namespaced_key? write_to
content= native_content= write_xhtml_to
create_external_subset next write_xml_to
create_internal_subset next= xml?
css next_element xpath
css_path next_sibling
decorate! node_name
Nokogiri::XML::Document#methods:
<< create_comment document name to_java
add_child create_element dup namespaces to_xml
canonicalize create_entity encoding remove_namespaces! url
clone create_text_node encoding= root validate
collect_namespaces decorate errors root= version
create_cdata decorators errors= slop!
Nokogiri::HTML::Document#methods:
fragment meta_encoding meta_encoding= serialize title title= type
self.methods: __pry__
instance variables: @decorators @errors @node_cache
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