● Work for Money Forward, Inc. ○ a Rails app engineer ○ an RBS maintainer ● Live in Okayama ● NOT flat earth believer Masataka Pocke Kuwabara GitHub: @pocke Twitter: @p_ck_ @[email protected]
Agenda This talks has two parts. ● Part 1: Introduce RBS features ○ Introduce new features of RBS 3.1 ○ Introduce rbs tools to write signatures (I don't have enough time!) ● Part 2: Demonstrate writing RBS ○ in an application ○ in ruby/rbs repository (I don't have enough time!)
● RBS basics ○ syntax, usage, etc ○ rbs collection ● RBS related tools ○ Steep, RBS Rails, etc I wrote an article to learn them (Japanese). https://pocke.hatenablog.com/entry/2023/ 05/08/184814 What I will NOT talk about in this presentation
What is rbs subtract rbs subtract removes duplicate RBS definitions. Usage: # Display the result of (a.rbs - b.rbs) $ rbs subtract a.rbs b.rbs # Overwrite a.rbs with the result directly $ rbs subtract --write a.rbs b.rbs This feature was developed by Saito-san (@tadd), and I took over it.
rbs subtract behavior $ rbs subtract a.rbs b.rbs # output (a.rbs - b.rbs) class C def bar: () -> untyped end # a.rbs class C def foo: () -> untyped def bar: () -> untyped end # b.rbs class C def foo: () -> Integer end You can find more examples from https://github.com/ruby/rbs/blob/master/test/rbs/subtractor_test.rb
● You are developing a large Ruby app, and you want to introduce RBS to the app. ● You run an RBS generator. ○ It generate RBS files from your codebase. ○ Generator is necessary because it's hard to write RBS files for entire application. Why necessary: example situation
Generated code is not perfect. $ cat test.rb class C def foo(int) = int.to_s end $ rbs prototype rb test.rb class C def foo: (untyped int) -> untyped end Why necessary: generated RBS
If you write a method definition to a separate file, you will get a duplication error. Why necessary: problem # auto-generated.rbs class C def foo: (untyped int) -> untyped end # hand-written.rbs class C def foo: (Integer int) -> String end # ::C#foo has duplicated definitions in hand-written.rbs
rbs subtract solves this problem. It removes well-described method definitions from auto-generated RBS files.
Why necessary: solution # auto-generated.rbs class C def foo: (untyped int) -> untyped end # hand-written.rbs class C def foo: (Integer int) -> String end # subtracted.rbs class C # No `foo` definition end
# Generate RBSs for all Ruby code under sig/prototype directory $ rbs prototype rb --out-dir=sig/prototype --base-dir=. app lib # Write type definitions by hand $ $EDITOR sig/hand-written/foo.rbs # Remove hand-written methods from generated RBSs $ rbs subtract --write sig/prototype sig/rbs_rails sig/hand-written # Type-check with the RBS files $ steep check A simple example workflow
This feature is implemented in ruby/rbs#1287. The design is described in a HackMD document. https://hackmd.io/seoMijXwRdG2uFITm2lLq w For more information
What is rbs parse ● rbs parse parses a .rbs file and report syntax errors. $ rbs parse valid.rbs # Print nothing $ rbs parse invalid.rbs test.rbs:4:0...4:3: Syntax error: cannot start a declaration, token=`end` (kEND) This feature is available since the first release (ruby/rbs#207).
What's New Two kinds of options has been available since RBS v3.1 (ruby/rbs#1252). ● -e CODE ○ Same as Ruby. ○ We can use this command without saving RBS code to a file. ● --type, --method-type ○ It specifies parsing context.
Example: -e Previously we need to save RBS code to a file to run rbs parse $ $EDITOR test.rbs && rbs parse test.rbs Since RBS 3.1, you do not need to save a file. $ rbs parse -e "class C end"
rbs collection ● It manages dependent libraries' RBSs. ● In short, Bundler for RBS. See my slides at RubyKaigi Takeout 2021 for more details https://rubykaigi.org/2021-tak eout/presentations/p_ck_.html
Other tools I also uses the following tools in the demonstration. ● Steep ○ Steep is a type checker working on RBS. ○ https://github.com/soutaro/steep ● RBS Rails ○ RBS Rails is an RBS generator for Rails applications. ○ https://github.com/pocke/rbs_rails
Editor Integrations Today I use VS Code and the following two extensions for the demonstration. ● RBS Syntax ● Steep But you can also uses other editors that support LSP. https://github.com/ruby/rbs/blob/master/d ocs/tools.md
【Money Forward x Shippio】 BaySide Tech Nite ● Shippio and Money Forward host this event. ● Talk about RubyKaigi and Ruby in English ● 2023-05-19 Tokyo https://moneyforward.connpass.co m/event/281065/ Unfortunately I cannot attend this event😢
● I, mame-san, and sinsoku-san will talk about OSS contribution in this event. ● 2023-05-25 Tokyo and Online ● Talk in Japanese https://timeedev.connpass.com/event/ 279568/
● I shared new features of RBS 3.1 ○ rbs subtract is a useful tool when you introduce RBS to a large app. ○ rbs prase evolved with new options. ● I shared demonstrations of introducing RBS.
Thanks for listening to my talk! Conclusion \ WE ARE HIRING / Scan to apply now!
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