The Well-Grounded Rubyist, Third Edition

Chapter 15. Callbacks, hooks, and runtime introspection

This chapter covers

• Runtime callbacks: inherited, included, and more
• The respond_to? and method_missing methods
• Introspection of object and class-method lists
• Trapping unresolved constant references
• Examining in-scope variables and constants
• Parsing caller and stack trace information

In keeping with its dynamic nature and its encouragement of flexible, supple object and program design, Ruby provides a large number of ways to examine what’s going on while your program is running and to set up event-based callbacks and hooks—essentially, tripwires that are pulled at specified times and for specific reasons—in the form of methods with special, reserved names for ...