ruby - 轨道外的 cattr_accessor

Question

我正在尝试使用 google_search ruby 库(代码如下)但它提示“cattr_accessor 是一个未定义的方法” - 任何想法为什么会这样或我如何解决它？

require 'rubygems'
require 'google_search'

GoogleSearch.web :q => "pink floyd"

Answer 1

cattr_accessor 似乎是一个 Rails 扩展 that acts like attr_accessor, but is accessible on both the class and its instances .

如果您想复制 cattr_accessor 方法的源代码，请查看 this documentation :

# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 46
def cattr_accessor(*syms)
  cattr_reader(*syms)
  cattr_writer(*syms)
end

# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 4
def cattr_reader(*syms)
  syms.flatten.each do |sym|
    next if sym.is_a?(Hash)
    class_eval("unless defined? @@\#{sym}\n@@\#{sym} = nil\nend\n\ndef self.\#{sym}\n@@\#{sym}\nend\n\ndef \#{sym}\n@@\#{sym}\nend\n", __FILE__, __LINE__)
  end
end

# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 24
def cattr_writer(*syms)
  options = syms.extract_options!
  syms.flatten.each do |sym|
    class_eval("unless defined? @@\#{sym}\n@@\#{sym} = nil\nend\n\ndef self.\#{sym}=(obj)\n@@\#{sym} = obj\nend\n\n\#{\"\ndef \#{sym}=(obj)\n@@\#{sym} = obj\nend\n\" unless options[:instance_writer] == false }\n", __FILE__, __LINE__)
  end
end