Help Collisions, Isolate the Worlds

The talk about https://bugs.ruby-lang.org/issues/19744
Why and how we will (not) introduce namespaces in Ruby
松江Ruby会議10

Transcript

1. Satoshi Tagomori a.k.a., @tagomoris দߐRubyձٞ10 - Sep 16, 2023 Help Collisions, Isolate the Worlds Names, Modules, Versions, and NameSpaces
2. Satoshi Tagomori (@tagomoris) Independent developer Technical Consultant OSS Maintainer • Fluentd • MessagePack / msgpack-ruby • Norikra, Woothee, … tagomoris
3. https://www. fl ickr.com/photos/takkanm/3978417669 Asakusa.rb
4. “Namespace on read“ https://bugs.ruby-lang.org/issues/19744
5. Collisions Destroy Developers’ Experience
6. Collisions Names, Modules, Versions Name Collisions: No one can use a name in two ways. Module Collisions: Modules can be modified, globally, from anywhere. Version Collisions: Two different versions of a module can’t be loaded.
7. Name Collisions No one can use a name in two ways. • A structured namespace: • Foo::Bar::Baz • Major scenario: • Top-level “Configuration” in gems • Typical RoR classes vs Ruby, Gems, etc (like “Guild”) • Two apps in a process (in the context of “Modular monolith”)
8. Module Collisions Modules can be modi fi ed, globally, from anywhere. • A single Module/Class instance • Oj.default_options
9. Version Collisions Two di ff erent versions of a library can’t be loaded. • Dependency hell • Module A depends on C ver 1.5.x • Module B depends on C ver 1.6.x • The App depends on A and B
10. Avoid Collisions
11. Isolate Worlds
12. NameSpaces In other words: “Multiverse Ruby” https://rubykaigi.org/2023/presentations/shioyama.html#day2
13. NameSpaces in Practice N languages, N ways • Library space • Global NameSpace (+ Version) • Local names only • Names in code • Library name • Local alias • Class loader
14. NameSpaces in languages Many ways, Many hells… • JavaScript/TypeScript (npm) • Local names + Local Aliases • Java (classes w/ FQDN) • Global NameSpace + Library name • Class loaders (oops….) • Kotlin • Global NameSpace + Local Alias • Python (pip) • Global NameSpace (+ Local Alias) • Go • Local names + Local Aliases
15. Ruby Many Libraries in a Global NameSpace
16. Libraries and NameSpaces Libraries can’t be re-de fi ned • Once a library lives globally, it can’t be locally • Ruby has a huge library set - RubyGems
17. NameSpace Requirements What is it? • One native extension libraries of two versions at a time • Same name, Di ff erent (native) code, Di ff erent access path (local name) • Isolate libraries in speci fi ed namespaces at the required time (“on read”) Ruby Process LibraryX version: a.b.c “x.so” LibraryX version: x.y.z “x.so” ns1::X ns2::X
18. NameSpace Requirements What is it? • One native extension libraries of two versions at a time • Same name, Di ff erent (native) code, Di ff erent access path (local name) • Isolate libraries in speci fi ed namespaces at the required time (“on read”) Ruby Process LibraryX version: a.b.c “x.so” LibraryX version: x.y.z “x.so” ns1::X X
19. My Proposal: module NameSpace < Module Respects load( fi lename, wrap) • The wrap of load(filename, wrap): • works as a simple namespace • Introduce a sub-class of Module: NameSpace • works like the wrap of load • has instance methods #require, #load • Dependencies will be required/loaded in the namespace recursively
20. Let’s go! DEMO
21. 🎉👏🍻 “Namespace on read PoC” https://github.com/tagomoris/ruby/pull/1
22. Hard Things, TODOs, Designs, … “How This Language Should Be?” • Hard Things: Native extension MAY need to be updated, in case • Native extensions using others’ C-functions
 https://github.com/tagomoris/sequel_pg/pull/1 • TODOs: Upgrade path SHOULD be de fi ned • How can we mark a gem is namespace-ready? • How can we determine the namespace of a library? (RubyGems/Bundler) • Designs • What’s the namespace in Ruby? • Problems around the top-level names in namespaces
23. Top-level Names in NameSpaces Should it be global? Or local? • “ns1::X” - A top-level name “X” de fi ned in a namespace “ns1” • It MUST be so, to isolate “ns1::X” from the “X” • “X” in the code isolated in “ns1” • It should be “ns1::X”, of course • But many gems add methods on “String” by “class String”… • “::X” in the code isolated in “ns1” • Should it be “ns1::X”? or the “X”? • “class ::String” should be possible
24. The TODOs I need discussions • To Go? Or No Go? • In this way? Or another way? Or NO WAY? • Which way to go? • How can we break codes IN NAMESPACES? (Not globally)
25. I NEED DISCUSSIONS For further developments. Thank you!