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What would you like to do?
Berkeley SaaS class HW1 Part 5: advanced OOP with some metaprogramming
# advanced OOP with some metaprogramming
class Class
def attr_accessor_with_history(attr_name)
attr_name = attr_name.to_s
# getter
attr_reader attr_name
attr_reader attr_name+"_history"
# 为类动态添加方法
class_eval %{
def #{attr_name}=(val)
@#{attr_name} = val
@#{attr_name}_history = [nil] if @#{attr_name}_history.nil?
class Foo
attr_accessor_with_history :bar
f = = 1 = 2
p f.bar_history # => if your code works, should be [nil,1,2]

thanks for showing me the correct way to do it but could you tell me where did you learn to do it? on the book of the course?

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