The document discusses the benefits of REPL-driven development using Pry, highlighting its effectiveness in providing short feedback loops for faster learning during coding and debugging. It emphasizes the advantages of using Pry for debugging, exploring, and understanding code with features like breakpoints, navigation commands, and a rich plugin ecosystem. The content also includes examples and references to additional resources for further learning about these techniques.

1. REPL-DRIVEN DEVELOPMENT
WITH PRY

2. ABOUT ME
Work as a contractor for Level 7 Custom Application
Development with a client called Groupize
stephenmarian0 on twitter (I’ll post the slides there)

3. GOALS
Why REPLs are so useful in general
Why Pry takes that to the next level
When and how to use REPL Driven Development over TDD
in some situations

4. WHY REPL?
You’re using a dynamic language. Exploit that fact and
shorten the feedback loop as much as you can.
Short feedback loops mean better and faster learning and
learning is what we’re doing all the time, whether we’re
debugging, going through documentation or developing
something new

5. WHY PRY?
Loads of additional functionality for debugging, source diving
and more
Rich Plugin ecosystem (examples later)

6. REPL-DRIVEN DEVELOPMENT
Use this fast feedback loop to help write code.
Discover, explore and understand
Where TDD is top-down REPL-Driven development is
bottom up
Useful for writing “draft” code when developing in a new
domain, using a new libraries, or anywhere else where the
solution design is not obvious.

7. EXAMPLE: PLAY AROUND
WITH A PUBLIC API

8. REVIEW: LESSON
binding.pry is your best friend when debugging
Source dive! All from the console
Gradually build up procedural code and “discover” an ideal
design

9. REVIEW: PRY SUPERPOWERS
cd and ls to navigate classes and methods
show-source and show-doc aliased to $ and ? respectively
_ and __ to get the last and penultimate returns respectively
. to execute shell commands from within pry
binding.pry to set a breakpoint
next and step to move through debugger using bye-bug
edit ClassName to enter your editor to edit that class

10. PLUGIN ECOSYSTEM
Examples:
Awesome Print for stylish pretty print.
Hirb for tabular collection output.
Pry Doc to browse Ruby source, including C, directly from the console.
Pry Remote to connect remotely to a Pry console.
Pry Coolline for syntax highlighting as you type.
All of the above available conveniently bundled together as part of the
jazz_fingers gem

11. ADDITIONAL RESOURCES
pryrepl.org
pry-rails
jazz_fingers
vim + tmux with slimux to send commands to pry in the
console

12. SOME TALKS
Avdi Grimm’s RubyTapas episode on REPL driven
development
Ruby Conf 2013: REPL Driven development with pry
Rails Conf 2013: Pry — the good parts
Rails Conf 2014 Debugger Driven Development with Pry