Lightning Talk on Metaprogramming in Ruby
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The document discusses metaprogramming in Ruby, emphasizing its ability to modify classes and objects dynamically during runtime. It provides examples of how to add methods to classes, such as the 'hearts' method for integers, and highlights features introduced in Ruby 2.0 that enhance safety. Additionally, it warns of the potential dangers of manipulating code and encourages responsible usage of these powerful capabilities.
Lightning Talk on Metaprogramming in Ruby
- 1. Metaprogramming what’s up with that
- 2. Yo, Dawg - I heard you like programming so I got you some meta so you can program your programs
- 3. Using Open Classes is Meta class Integer def hearts self.times do print "u2764 " end end end irb(main):003:0> require "./meta.rb" => true irb(main):004:0> 3.hearts ❤ ❤ ❤ => 3 irb(main):005:0> 1.hearts ❤ => 1
- 4. Objects and Classes Object stores only variables and a reference to the Class Class stores only methods (both instance and class methods) class = :Animal @says = “bark” def speak puts @says end
- 5. A class is an object! you can change variables on an object you can change methods on a class in ruby, you can do this whenever you want if your code changes other code, especially when running, that’s metaprogramming
- 6. Text Can be dangerous! But ruby 2.0 makes it safer
- 7. Refine is safer (ruby 2) module MadHacks refine Integer do def hearts self.times do print "u2764 " end end end end ! irb(main):001:0> require "./meta.rb" => true irb(main):002:0> 1.hearts NoMethodError: undefined method `hearts' for 1:Fixnum from (irb):2 from /Users/mindlace/.rbenv/versions/2.0.0-p247/bin/irb:12:in `<main>' irb(main):003:0> using MadHacks => main irb(main):004:0> 1.hearts ❤ => 1
- 8. Lots of other techniques Dynamic methods (add methods when they are named) Method missing (respond to any method name) And more! Ruby makes it very easy to metaprogram With power comes responsibility
- 9. Questions?