Training RuboCop / XND and rubyplot

Wed, 05 Dec 2018 19:00 - 21:30 JST


東京都渋谷区渋谷二丁目12番19号 東建インターナショナルビル5階


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Drinks and a light meal will be provided



19:00 〜 19:30 Doors open

Grab a drink and catch up with your fellow Rubyists.

19:30 〜 19:55 Training RuboCop - for cleaner, more consistent Ruby code Masafumi Okura

RuboCop is a Ruby static code analyzer (a.k.a. linter) and code formatter. It not only makes coding guideline explicit, but also lets us fix code problems on the fly. These features are great for experienced developers to keep code clean with less effort and for juniors to learn how to write Ruby code more quickly.

However, some of default rules are sometimes confusing, outdated, or simply unnecessary. Those rules make it hard to use RuboCop in production. Maintaining app code is already hard and time consuming, so why spend even more time to customize RuboCop?

Well it turned out for us that RuboCop is worth using from day one of development. You can train RuboCop as your app grows so that it naturally fits your real needs.

In this talk, I'll introduce RuboCop, how it can be useful for both experienced and new developers, and tips on customizing it for teams.


Masafumi is a web developer with more than five years of Ruby/Rails experience. He's working for a startup called Cycle where he has built the backends of apps for farmers, maintained AWS infrastructures, and recruited new developers. His current technical interest is how to keep code clean and development speed fast with tools like RSpec and RuboCop.

20:00 〜 20:25 XND and rubyplot - future of typed arrays and visualization in Ruby Sameer Deshmukh

The Ruby scientific computing ecosystem has suffered from two major drawbacks so far: the lack of a suitable library for typed arrays to serve as a common foundation and the lack of a robust and well maintained visualization library. In this talk I will talk about two endeavors in order to address these issues - XND and rubyplot.

XND aims to be the go-to library in Ruby for defining typed arrays. It aims to provide a simple, modular and well maintained library for this purpose. It provides robust interfaces for type specification, views and various math functions.

Rubyplot aims to be the most powerful native visualization tool for Ruby. It does this by directly interfacing with back-ends like Image Magick or GR and providing a Ruby-like plotting interface and an optional Matlab-like interface.

Additionally, both libraries are regularly maintained and updated by Quansight Inc, a company founded with the purpose of growing and maintaining open source software tools.


XND Ruby wrapper:
Quansight Inc:


Sameer is a student and a contributor to the Ruby Science Foundation, where he helps build scientific computation tools in Ruby. He is currently working on Rubex, a new language for easily writing C extensions for the CRuby interpreter. He enjoys spending spare time with friends, books and his bass guitar.

20:30 〜 20:35 Announcements

Have something you want to announce? For instance, is your company looking to hire Ruby developers? Or do you have an event you're organizing? This is your chance to announce it to the community. Get in touch in advance if you have something you'd like to announce.

20:35 〜 21:30 Open Networking

Discuss the presentations or anything else Ruby related with the other attendees.

Venue Sponsor

PIXTA's engineers use Ruby on Rails to build their stock photo marketplace, and are looking for developers to join their team. You can learn more about what they're working on through their engineering blog.

About the Venue

From 19:00, the main entrance of the building is locked. Please use the back entrance (裏手 in Japanese, see this picture of it). The back entrance will be locked from 8pm onwards, so please be sure to show up before then.

About this community

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup

Tokyo Rubyist Meetup (trbmeetup) is an event that seeks to help bridge the Japan and international ruby and ruby on rails community. It will hold regular meetings where Japanese Rubyists can commun...

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