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# -*- encoding: utf-8 -*-
module Aliyun
module Common
# Common structs used. It provides a 'attrs' helper method for
# subclass to define its attributes. 'attrs' is based on
# attr_reader and provide additional functionalities for classes
# that inherits Struct::Base :
# * the constuctor is provided to accept options and set the
# corresponding attibute automatically
# * the #to_s method is rewrite to concatenate the defined
# attributes keys and values
# @example
# class X < Struct::Base
# attrs :foo, :bar
# end
#
# x.new(:foo => 'hello', :bar => 'world')
# x.foo # == "hello"
# x.bar # == "world"
# x.to_s # == "foo: hello, bar: world"
module Struct
class Base
module AttrHelper
def attrs(*s)
define_method(:attrs) {s}
attr_reader(*s)
end
end
extend AttrHelper
def initialize(opts = {})
extra_keys = opts.keys - attrs
unless extra_keys.empty?
fail Common::Exception,
"Unexpected extra keys: #{extra_keys.join(', ')}"
end
attrs.each do |attr|
instance_variable_set("@#{attr}", opts[attr])
end
end
def to_s
attrs.map do |attr|
v = instance_variable_get("@#{attr}")
"#{attr.to_s}: #{v}"
end.join(", ")
end
end # Base
end # Struct
end # Common
end # Aliyun
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