Book Report on Avdi Grimm's excellent 'Confident Ruby'

1. Confident Ruby
Be A Coding Hemingway

2. Confident Ruby
Avdi Grimm
http://www.rubytapas.com/

3. Doesn’t:
Does:
● Application Design
● Patterns for writing
confident Ruby
code at the method
level
● Object Modeling

4. “CODE
AS NARRATIVE”

5. Collecting Input
Performing Work
Delivering Output
Handling Errors
Responsibilities

6. Conversion Methods
Special Case Object
Receive Policies

7. Conversion Methods
Conversion Methods for Coercing Inputs

8. Type checking
Nested control structures
(‘if/else’ blocks)
Checking for ‘nil’ (type
checking)

9. Explicit Conversion
● #to_a, #to_i, #to_s
● objects don’t resemble the target type
● Implemented by Ruby types but not
called

10. Implicit Conversion
● #to_ary, #to_int, #to_str
● objects closely resemble the target type
● Called by Ruby but not implemented

11. Kernel Level Conversion Methods
● Array(), Integer(), String()
● Try implicit and explicit conversions
● Bag o’ tricks

12. Flexible
Coherent
Confident ; )

13. Conversion Methods
Special Case Object

14. Conversion Methods
=>

15. Special Case Object
● isolate the differences to a single object
● Leverage polymorphism by conforming to
a protocol

16. Confident
Expressive
Flexible
=>

17. “The foundation of an object
oriented system is the message”
-Sandi Metz, Practical Object-Oriented Design in Ruby

18. Conversion Methods
Receive Policies Instead of Data

19. Delegate Responsibility to Client Code
“Put the decision for how to handle
test cases in the hands of the code
best qualified to determine the
appropriate response.”

20. ● Intent of the method
is obscured
● Calling code is not
self-documenting
● Little flexibility.
What if we want
more than 2 ways to
handle errors?
Passing data/flags

21. ● Pass policies as
block/proc/lambda
objects
● Stop handling edge
cases from obfuscating
the method’s intent
● Flexibility - let’s the
client code handle
decision making
Passing Policies

22. Example: Ruby’s
Enumerable#detect

23. Write code that
tells a story
Confident Ruby - Avdi Grimm