Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Efficient debugging with Pry
Search
Conrad Irwin
October 02, 2012
Programming
2
360
Efficient debugging with Pry
A short talk summarizing how to use Pry to save yourself time when debugging.
Conrad Irwin
October 02, 2012
Tweet
Share
More Decks by Conrad Irwin
See All by Conrad Irwin
Go for Rubyists
conradirwin
2
260
REPL Driven Development with Pry!
conradirwin
5
1.5k
MongoDB — confessions of a PostgreSQL lover
conradirwin
3
3.6k
Debugging with Pry
conradirwin
0
130
Debuggable Code
conradirwin
1
240
Pry — the good parts!
conradirwin
25
1.6k
Other Decks in Programming
See All in Programming
Startups on Rails in Past, Present and Future–Irina Nazarova, RailsConf 2025
irinanazarova
0
140
LT 2025-06-30: プロダクトエンジニアの役割
yamamotok
0
790
AI Agent 時代のソフトウェア開発を支える AWS Cloud Development Kit (CDK)
konokenj
3
260
AIプログラマーDevinは PHPerの夢を見るか?
shinyasaita
1
230
Flutterで備える!Accessibility Nutrition Labels完全ガイド
yuukiw00w
0
170
Porting a visionOS App to Android XR
akkeylab
0
590
おやつのお供はお決まりですか?@WWDC25 Recap -Japan-\(region).swift
shingangan
0
140
状態遷移図を書こう / Sequence Chart vs State Diagram
orgachem
PRO
1
130
Claude Code + Container Use と Cursor で作る ローカル並列開発環境のススメ / ccc local dev
kaelaela
10
6k
Rubyでやりたい駆動開発 / Ruby driven development
chobishiba
1
740
オンコール⼊⾨〜ページャーが鳴る前に、あなたが備えられること〜 / Before The Pager Rings
yktakaha4
0
120
すべてのコンテキストを、 ユーザー価値に変える
applism118
3
1.4k
Featured
See All Featured
Practical Tips for Bootstrapping Information Extraction Pipelines
honnibal
PRO
20
1.3k
Documentation Writing (for coders)
carmenintech
72
4.9k
RailsConf & Balkan Ruby 2019: The Past, Present, and Future of Rails at GitHub
eileencodes
138
34k
Let's Do A Bunch of Simple Stuff to Make Websites Faster
chriscoyier
507
140k
A designer walks into a library…
pauljervisheath
207
24k
Testing 201, or: Great Expectations
jmmastey
43
7.6k
CoffeeScript is Beautiful & I Never Want to Write Plain JavaScript Again
sstephenson
161
15k
The Invisible Side of Design
smashingmag
301
51k
Rails Girls Zürich Keynote
gr2m
95
14k
JavaScript: Past, Present, and Future - NDC Porto 2020
reverentgeek
50
5.5k
Designing Dashboards & Data Visualisations in Web Apps
destraynor
231
53k
Making the Leap to Tech Lead
cromwellryan
134
9.4k
Transcript
None
Debugging l Figure out why the code is broken l
Fix it l Repeat.
puts l Most common debugging tool l Very easy to
use l Gather information one chunk at a time
binding.pry l Opens pry at that line in your code
l `gem install pry` l Gather as much information as you need l Test theories immediately
pry-rescue l Automatic binding.pry on unhandled exceptions l `gem install
pry-rescue` l Reduces feedback cycle times
NoMethodError l Most common exception in ruby code? l Caused
by: - Typos - Forgetting the right method name - Using the wrong object
ls -‐-‐grep l Finds the correct method l No
need to google l Doesn't rely on gems having docs ;)
[1] pry(main)> ls Base64 -‐-‐grep encode Base64.methods:
encode64 strict_encode64 urlsafe_encode64 [2] pry(main)>
ls -‐-‐grep l Finds the correct method l No
need to google l Doesn't rely on gems having docs ;)
edit -‐-‐ex l Opens your text editor l Jumps
to the exception l Reloads the code when you're done
From: /0/ruby/pry/example.rb @ line 3: 3:
def base64ify(email) => 4: Base64.encode(email) 5: end NoMethodError: undefined method `encode' for Base64:Module' [1] pry(main)>
From: /0/ruby/pry/example.rb @ line 3: 3:
def base64ify(email) => 4: Base64.encode(email) 5: end NoMethodError: undefined method `encode' for Base64:Module' [1] pry(main)> edit -‐-‐ex
None
[1] pry(main)> edit -‐-‐ex 3: def
base64ify(email) => 4: Base64.encode64(email) 5: end [2] pry(main)> base64ify("hello world") "aGVsbG8gd29ybGQ=\n"
up and down l Moves pry up and down the
call stack l Figure out why you have the wrong object l Discover why a gem doesn't work l `gem install pry-stack_explorer`
From: /0/ruby/pry/example2.rb @ line 2: 2:
def make_safe(text) => 3: text.gsub(/[^a-‐z]/i, '-‐') 4: end NoMethodError: undefined method `gsub' for nil:NilClass' [1] pry(main)>
[1] pry(main)> up From: /0/ruby/pry/example2.rb @ line 6:
2: def safe_title(post) => 3: make_safe(post[:title]) 4: end [2] pry(main)> post {"title" => "Hello Pry"}
up and down l Moves pry up and down the
call stack l Figure out why you have the wrong object l Discover why a gem doesn't work l `gem install pry-stack_explorer`
$ and ? l show-source and show-doc l Instant documentation
when you need it l No need to `cd` into gem directories.
[1] pry(main)> $ safe_title 2: def
safe_title(post) 3: make_safe(post[:title]) 4: end [2] pry(main)>
[2] pry(main)> ? safe_title Convert the title of the
blog into a string suitable for use in URLs. param [Hash] post return [String] [3] pry(main)>
In conclusion l Debugging requires gathering information l Get into
a `binding.pry` habit l Explore pry's extra features - gem install pry-full - Type `help` inside pry
<EOF> l @ConradIrwin (github, twitter, gmail, etc.) l http://pryrepl.org/ l
irc://freenode.net/#pry