Ruby Language
Интроспекция в Ruby

Вступление

Давайте посмотрим на некоторые примеры

Пример:

s = "Hello"  # s is a string

Затем мы узнаем что-то о s. Давай начнем:

Итак, вы хотите знать, что такое класс s во время выполнения?

irb(main):055:0* s.class
=> String

Аааа, прекрасно. Но каковы методы s?

irb(main):002:0> s.methods
=> [:unicode_normalize, :include?, :to_c, :unicode_normalize!, :unicode_normalized?, :%, :*, :+, :count, :partition, :unpack, :encode, :encode!, :next, :casecmp, :insert, :bytesize, :match, :succ!, :next!, :upto, :index, :rindex, :replace, :clear, :chr, :+@, :-@, :setbyte, :getbyte, :<=>, :<<, :scrub, :scrub!, :byteslice, :==, :===, :dump, :=~, :downcase, :[], :[]=, :upcase, :downcase!, :capitalize, :swapcase, :upcase!, :oct, :empty?, :eql?, :hex, :chars, :split, :capitalize!, :swapcase!, :concat, :codepoints, :reverse, :lines, :bytes, :prepend, :scan, :ord, :reverse!, :center, :sub, :freeze, :inspect, :intern, :end_with?, :gsub, :chop, :crypt, :gsub!, :start_with?, :rstrip, :sub!, :ljust, :length, :size, :strip!, :succ, :rstrip!, :chomp, :strip, :rjust, :lstrip!, :tr!, :chomp!, :squeeze, :lstrip, :tr_s!, :to_str, :to_sym, :chop!, :each_byte, :each_char, :each_codepoint, :to_s, :to_i, :tr_s, :delete, :encoding, :force_encoding, :sum, :delete!, :squeeze!, :tr, :to_f, :valid_encoding?, :slice, :slice!, :rpartition, :each_line, :b, :ascii_only?, :hash, :to_r, :<, :>, :<=, :>=, :between?, :instance_of?, :public_send, :instance_variable_get, :instance_variable_set, :instance_variable_defined?, :remove_instance_variable, :private_methods, :kind_of?, :instance_variables, :tap, :is_a?, :extend, :to_enum, :enum_for, :!~, :respond_to?, :display, :object_id, :send, :method, :public_method, :singleton_method, :define_singleton_method, :nil?, :class, :singleton_class, :clone, :dup, :itself, :taint, :tainted?, :untaint, :untrust, :trust, :untrusted?, :methods, :protected_methods, :frozen?, :public_methods, :singleton_methods, :!, :!=, :__send__, :equal?, :instance_eval, :instance_exec, :__id__]

Вы хотите знать, является ли s экземпляром String?

irb(main):017:0*
irb(main):018:0* s.instance_of?(String)
=> true

Каковы общедоступные методы s?

irb(main):026:0* s.public_methods
=> [:unicode_normalize, :include?, :to_c, :unicode_normalize!, :unicode_normalized?, :%, :*, :+, :count, :partition, :unpack, :encode, :encode!, :next, :casecmp, :insert, :bytesize, :match, :succ!, :next!, :upto, :index, :rindex, :replace, :clear, :chr, :+@, :-@, :setbyte, :getbyte, :<=>, :<<, :scrub, :scrub!, :byteslice, :==, :===, :dump, :=~, :downcase, :[], :[]=, :upcase, :downcase!, :capitalize, :swapcase, :upcase!, :oct, :empty?, :eql?, :hex, :chars, :split, :capitalize!, :swapcase!, :concat, :codepoints, :reverse, :lines, :bytes, :prepend, :scan, :ord, :reverse!, :center, :sub, :freeze, :inspect, :intern, :end_with?, :gsub, :chop, :crypt, :gsub!, :start_with?, :rstrip, :sub!, :ljust, :length, :size, :strip!, :succ, :rstrip!, :chomp, :strip, :rjust, :lstrip!, :tr!, :chomp!, :squeeze, :lstrip, :tr_s!, :to_str, :to_sym, :chop!, :each_byte, :each_char, :each_codepoint, :to_s, :to_i, :tr_s, :delete, :encoding, :force_encoding, :sum, :delete!, :squeeze!, :tr, :to_f, :valid_encoding?, :slice, :slice!, :rpartition, :each_line, :b, :ascii_only?, :hash, :to_r, :<, :>, :<=, :>=, :between?, :pretty_print, :pretty_print_cycle, :pretty_print_instance_variables, :pretty_print_inspect, :instance_of?, :public_send, :instance_variable_get, :instance_variable_set, :instance_variable_defined?, :remove_instance_variable, :private_methods, :kind_of?, :instance_variables, :tap, :pretty_inspect, :is_a?, :extend, :to_enum, :enum_for, :!~, :respond_to?, :display, :object_id, :send, :method, :public_method, :singleton_method, :define_singleton_method, :nil?, :class, :singleton_class, :clone, :dup, :itself, :taint, :tainted?, :untaint, :untrust, :trust, :untrusted?, :methods, :protected_methods, :frozen?, :public_methods, :singleton_methods, :!, :!=, :__send__, :equal?, :instance_eval, :instance_exec, :__id__]

и частные методы ....

irb(main):030:0* s.private_methods
=> [:initialize, :initialize_copy, :DelegateClass, :default_src_encoding, :irb_binding, :sprintf, :format, :Integer, :Float, :String, :Array, :Hash, :catch, :throw, :loop, :block_given?, :Complex, :set_trace_func, :trace_var, :untrace_var, :at_exit, :Rational, :caller, :caller_locations, :select, :test, :fork, :exit, :`, :gem_original_require, :sleep, :pp, :respond_to_missing?, :load, :exec, :exit!, :system, :spawn, :abort, :syscall, :printf, :open, :putc, :print, :readline, :puts, :p, :srand, :readlines, :gets, :rand, :proc, :lambda, :trap, :initialize_clone, :initialize_dup, :gem, :require, :require_relative, :autoload, :autoload?, :binding, :local_variables, :warn, :raise, :fail, :global_variables, :__method__, :__callee__, :__dir__, :eval, :iterator?, :method_missing, :singleton_method_added, :singleton_method_removed, :singleton_method_undefined]

Да, у них есть имя метода сверху. Вы хотите получить версию s верхнего регистра? Давай попробуем:

irb(main):044:0> s.respond_to?(:upper)
=> false

Похоже, нет, правильный метод - это верхняя шкала, позволяющая проверить:

irb(main):047:0*
irb(main):048:0* s.respond_to?(:upcase)
=> true

Интроспекция класса

Ниже приведено определение класса

class A
   def a; end
end

module B
   def b; end
end

class C < A
   include B
   def c; end
end

Каковы методы экземпляра C ?

C.instance_methods # [:c, :b, :a, :to_json, :instance_of?...]

Каковы методы экземпляра, которые объявляются только на C ?

C.instance_methods(false) # [:c]

Каковы предки класса C ?

C.ancestors # [C, B, A, Object,...]

Суперкласс C ?

C.superclass # A