The case of the missing method — a Ruby mystery story
summary
A Ruby method lookup mystery gets solved by reproducing the bug in Pry/IRB, inspecting ObjectSpace counts, and writing a small where helper that walks ancestors; the missing method does not live on Class but on the object's singleton class, revealed by filtering methods and checking singleton_class ancestors. The talk shows a working DSL built with instance_eval (City.construct) to create per-city behavior, explains why class methods are really singleton-instance methods, and demos how this causes the undefined method error.
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chapters (12)
- 0:00Intro
- 1:20Mike and Jenny
- 6:27Ever heard of Google
- 10:00Smalltalk
- 13:36The phone call
- 14:24What are Singleton classes
- 15:24Budgeting Inc
- 16:15Creating a DSL
- 21:35Singleton classes
- 24:45Mike
- 27:06Ellen
- 28:13Ruby Core Team
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