Autoloading from subdirectory with same name as ruby file doesn't work

[schuetzm]

Autoloading doesn't seem to work with a file hierarchy like this:

app/models/book.rb          Book
app/models/book/bla.rb      Book::Bla < Book

How to reproduce:

mkdir /tmp/zw && cd /tmp/zw
rails new .
echo "class Book ; end" > app/models/book.rb
mkdir app/models/book
echo "class Book::Bla < Book ; end" > app/models/book/bla.rb
rails console

Then, trying to access Book::Bla does not autoload app/models/book/bla.rb:

Loading development environment (Rails 6.0.0.beta3)
2.5.1 :001 > Book
 => Book 
2.5.1 :002 > Book::Bla
Traceback (most recent call last):
        1: from (irb):2
NameError (uninitialized constant Book::Bla)

[casperisfine]

I tested with the following test case:

  test "autoloads inheriting from parent namespace" do
    files = [
      ["a.rb", "class A; end"],
      ["a/x.rb", "class A::X < A; end"],
    ]
    with_setup(files) do
      assert A::X
    end
  end

It works fine.

However since this is an explicit namespace, I think it's likely you are being hit by the ISeq loading not triggering TracePoint callbacks.

Can you try disabling bootsnap in config/boot.rb and retry ? This is a known issue and we're waiting for a fix from MRI.

[fxn]

Sure, see rails/rails#35475 for background and some workarounds.

[fxn]

Closing here, since Zeitwerk itself is good, and that issue in Rails has it covered.

[schuetzm]

@casperisfine Thanks, it indeed works without bootsnap.

[bibendi]

It seems when I use pry-byebug the autoload still have this problem. The problem appears when I'm trying to debug when entering to binding.pry at some point of code.

I have these files:

app/graphql/types.rb

module Types
  ...
end

app/graphql/types/base.rb

module Types
  class Base
  ...
end

require "pry-byebug"
...
binding.pry
> [1] pry(#<RSpec::ExampleGroups::MeChatRooms>)> Types::Base
NameError: uninitialized constant Types::Base

Without pry-byebug all worked fine.

I have Ruby 2.6.1 and Rails 6 beta 3.

[fxn]

Can you reproduce that in a minimal pure Ruby setup?

[palkan]

@fxn More information for the case above:

[19] pry(#<RSpec::ExampleGroups::PerkIdId>)> PerksBy::Types::Perk
NameError: uninitialized constant PerksBy::Types::Perk
Did you mean?  PerksBy::Perk
               PerksBy::Perks

[20] pry> Zeitwerk::Registry.loaders
=> [#<Zeitwerk::Loader:0x000055c520803ed8
  @autoloads=
   {"/app/engines/perks_by/spec/internal/app/graphql/test_schema.rb"=>[Object, "TestSchema"],
    "/app/engines/perks_by/app/graphql/perks_by/query_interface.rb"=>[PerksBy, "QueryInterface"],
    "/app/engines/perks_by/app/graphql/perks_by/types.rb"=>[PerksBy, "Types"],
    "/app/engines/perks_by/app/models/perks_by/city_perk.rb"=>[PerksBy, "CityPerk"],
    "/app/engines/perks_by/app/models/perks_by/perk.rb"=>[PerksBy, "Perk"],
    "/app/engines/perks_by/app/models/perks_by/perk_type.rb"=>[PerksBy, "PerkType"],
    "/app/engines/perks_by/app/policies/perks_by/perk_policy.rb"=>[PerksBy, "PerkPolicy"],
    "/app/engines/perks_by/app/queries/perks_by/perks"=>[PerksBy, "Perks"]
     
    ...

    @lazy_subdirs=
   {"PerksBy::Types"=>["/app/engines/perks_by/app/graphql/perks_by/types"],

So, the dir with the file appears in the lazy_subdirs.

Also logs:

Zeitwerk@rails.main: autoload set for TestSchema, to be loaded from /app/engines/perks_by/spec/internal/app/graphql/test_schema.rb
Zeitwerk@rails.main: autoload set for PerksBy::Types, to be autovivified from /app/engines/perks_by/app/graphql/perks_by/types
Zeitwerk@rails.main: autoload set for PerksBy::QueryInterface, to be loaded from /app/engines/perks_by/app/graphql/perks_by/query_interface.rb
Zeitwerk@rails.main: autoload set for PerksBy::Types, to be loaded from /app/engines/perks_by/app/graphql/perks_by/types.rb

# nothing for /app/engines/perks_by/app/graphql/perks_by/types/perk.rb

[1] pry> PerksBy::Types::Perk
Zeitwerk@rails.main: constant PerksBy::Types loaded from file /app/engines/perks_by/app/graphql/perks_by/types.rb
NameError: uninitialized constant PerksBy::Types::Perk

Without pry-byebug all worked fine.

In my case (@bibendi could you check please, too), the failure only occurs only in the debugging context (i.e. within a Pry session after hitting a binding.pry). The presence of require "pry-byebug" itself doesn't break anything.

[palkan]

@fxn Well, I found the cause: byebug stops the main execution thread thus making TracePoint no-op:

• https://github.com/deivid-rodriguez/byebug/blob/4b8a289500a8ae1e3bdf30c7aceec50ce0cdb6b7/lib/byebug/helpers/eval.rb#L85-L99
• https://github.com/deivid-rodriguez/byebug/blob/4b8a289500a8ae1e3bdf30c7aceec50ce0cdb6b7/ext/byebug/threads.c#L138

And that's a bad news( byebug is a default Rails debugger.

One possible solution is to activate the TracePoint in its own thread (though adding this just to make one specific debugger happy sounds strange).

[fxn]

I have some stuff with higher priority in Zeitwerk, but will eventually get to this.

I’ll try also to understand if this is an issue that should have to be opened in byebug, since Zeitwerk is using ordinary Ruby and it is the debugger the one changing part of that.

Bootsnap for example implemented a couple of things to comply with edgy but standard Ruby semantics Zeitwerk relies on.

Let’s see!

[marshall-lee]

Hi everyone! If you're still interested I made a fix for byebug + zeitwerk compatibility. deivid-rodriguez/byebug#847