cattr_accessor outside of rails

Question

I\'m trying to use the google_search ruby library (code follows) but it complains that \'cattr_accessor is an undefined method\' - any ideas why this might be o

Answer 1

You can get this functionality by including the Ruby Facets gem. Reference the source here:

https://github.com/rubyworks/facets/blob/master/lib/core/facets/cattr.rb

You generally don't need to require all code from the gem. You can selectively require what you want. There are quite a few useful extensions in the gem though.

Answer 2

cattr_accessor seems to be a Rails extension that acts like attr_accessor, but is accessible on both the class and its instances.

If you want to copy the source of the cattr_accessor method, check out 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