def ... end syntax vs define_method

test.rb

class Test
    def initialize
        @a = 100
    end

    a = 100
    def test1
        a
    end

    define_method('test2'){ a }
     
    def test3
        @a
    end
end


t = Test.new
begin
puts t.test1 # def ... end does not establish closure, so cannot access free variable
rescue => e
    puts e.inspect
end
puts t.test2 # define_method established a closure

require 'benchmark'


n = 500000

Benchmark.bm do |x|
    x.report { n.times { t.test2 } }
    x.report { n.times { t.test3 } }
end