Ok, just bumping this topic because it is actually affecting us now. (What
timing, eh?)
When we deploy new code to passenger-enterprise-server-4.0.37 with Rails
4.0.2, at times things have been remove_const'd and I'm assuming that
passenger is expecting that Rails autoloading with autoload the constant on
second reference? I would at least.
I'm probably just not remembering something, but I'm curious why Rails is
not autoloading on reference after a const is unloaded? It seems that
instead of raising "Circular dependency detected while autoloading
constant..." it would just reload the file, but maybe it doesn't know which
to reload?
On Tuesday, February 18, 2014 4:14:59 PM UTC-5, Gary Weaver wrote:
>
> Notice how a class that is not available is a NameError and a constant
> unloaded from ActiveSupport::Dependencies or via remove_const called on the
> module is a RuntimeError about a circular dependency...
>
> The class I unloaded has no references to or from anywhere else.
>
> Just to show how a missing constant behaves normally:
>
> Loading development environment (Rails 4.0.2)
> 2.1.0 :001 > Nothing::Nothing.to_s
> NameError: uninitialized constant Nothing
> from (irb):1
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:90:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:9:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands.rb:62:in `<top
> (required)>'
> from bin/rails:4:in `require'
> from bin/rails:4:in `<main>'
>
> Now, how a missing constant behaves after being undefined by Rails 4.0.2:
>
> 2.1.0 :002 > Object.const_defined? 'MyModule::MyClass'
> => false
> 2.1.0 :003 > MyModule::MyClass.to_s
> => "MyModule::MyClass"
> 2.1.0 :004 > Object.const_defined? 'MyModule::MyClass'
> => true
> 2.1.0 :005 > ActiveSupport::Dependencies.remove_constant MyModule::MyClass
> => MyModule::MyClass
> 2.1.0 :006 > Object.const_defined? 'MyModule::MyClass'
> => false
> 2.1.0 :007 > MyModule::MyClass.to_s
> RuntimeError: Circular dependency detected while autoloading constant
> MyModule::MyClass
> from
> /path/to/gemset/activesupport-4.0.2/lib/active_support/dependencies.rb:461:in
> `load_missing_constant'
> from
> /path/to/gemset/activesupport-4.0.2/lib/active_support/dependencies.rb:184:in
> `const_missing'
> from (irb):7
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:90:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:9:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands.rb:62:in `<top
> (required)>'
> from bin/rails:4:in `require'
> from bin/rails:4:in `<main>'
> 2.1.0 :008 > load
> "#{Rails.root}/app/an_autoloaded_dir/my_module/my_class.rb"
> => true
> 2.1.0 :009 > MyModule::MyClass.to_s
> => "MyModule::MyClass"
> 2.1.0 :010 > MyModule.send(:remove_const, :MyClass)
> => MyModule::MyClass
> 2.1.0 :011 > Object.const_defined? 'MyModule::MyClass'
> => false
> 2.1.0 :012 > MyModule::MyClass.to_s
> RuntimeError: Circular dependency detected while autoloading constant
> MyModule::MyClass
> from
> /path/to/gemset/activesupport-4.0.2/lib/active_support/dependencies.rb:461:in
> `load_missing_constant'
> from
> /path/to/gemset/activesupport-4.0.2/lib/active_support/dependencies.rb:184:in
> `const_missing'
> from (irb):23
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:90:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:9:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands.rb:62:in `<top
> (required)>'
> from bin/rails:4:in `require'
> from bin/rails:4:in `<main>'
> 2.1.0 :013 > load "#{Rails.root}/app/workflow/my_module/my_class.rb"
> => true
> 2.1.0 :015 > MyModule::MyClass.to_s
> NameError: uninitialized constant MyModule
> from (irb):26
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:90:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands/console.rb:9:in
> `start'
> from /path/to/gemset/railties-4.0.2/lib/rails/commands.rb:62:in `<top
> (required)>'
> from bin/rails:4:in `require'
> from bin/rails:4:in `<main>'
> 2.1.0 :016 > MyModule::MyClass.to_s
> => "MyModule::MyClass"
>
> I'm curious what the circular dependency would be there, since there are
> no other references to the class, afaik.
>
> Thanks!
>
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