Add the Metaprogramming Ruby book to Model

Author: gmalette

_posts/2019-02-01-the-ruby-object-model.md

@@ -11,6 +11,7 @@ Recently I was called out. I hypothesized that some bad patterns in Ruby are cau
 **Edit:** I've been sent other resources about Ruby's Object Model:
 - [All I'd Wanted to Know about Ruby's Object Model Starting Out...and Mooar!!!](https://www.youtube.com/watch?v=268UU4EpTew) in which Jun Qi Tan explains what I tried to in this post, in a much more eloquent talk.
 - [Unraveling Classes, Instances and Metaclasses in Ruby](https://blog.appsignal.com/2019/02/05/ruby-magic-classes-instances-and-metaclasses.html) by Jeff Kreeftmeijer in the excellent Ruby Magic series.
+- [Metaprogramming in Ruby](https://pragprog.com/book/ppmetr2/metaprogramming-ruby-2) by Paolo Perrotta has a section on the object model.
 
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