Em 08-02-2013 13:03, Xavier Noria escreveu:
On Fri, Feb 8, 2013 at 3:18 PM, Rodrigo Rosenfeld Rosas
<[email protected]> wrote:
Em 08-02-2013 12:06, Xavier Noria escreveu:
Seems unrelated to dependencies.rb, most likely a missing require
somewhere within Rails.
It can be the case that it does not show up in production because of eager
loading.
Any ideas why helpers.rb is loaded when you write code like below?
module ActionView
module Helpers
module NumberHelper
Is this normal MRI behavior or is this caused by dependencies.rb?
Ruby on Rails itself does not use dependencies.rb to load its code. It
is a regular Ruby library that uses requires and Kernel#autoload with
some added sugar. AS::Dependencies only covers application constant
autoloading.
The thing goes like this: When an application boots in any environment
action_view.rb is loaded. When that file is executed an autoload for
:Helpers is configured under ActionView. In a default setup,
helpers.rb is not yet loaded. That is, if you run
rails runner 1
helpers.rb is not loaded (at least in 3-2-stable, not that we are
explaining any contract, only load order execution to follow what
happens in your exception).
But if you force the evaluation of the constant as in your example above:
module ActionView
module Helpers
...
end
end
that autoload is triggered because the interpreter checks whether
"Helpers" is a constant defined in the module object stored in
ActionView. Therefore, helpers.rb is interpreted and sets in turn an
autoload for NumberHelper below AV::Helpers.
So, module Helpers in that snippet *reopens* a module object defined
via the autoload, rather than creating the module object. The
execution follows and the same happens with the "NumberHelper"
constant down below. The interpreter checks whether it belongs to the
module object stored in AV::Helpers. Since it is unknown and there is
an autoload for it it gets triggered, and loads... well the very
number_helper.rb whose execution we were in the middle of (not sure
this sentence is valid English :).
I suspect there is a circularity here that is showing up that way.
Would need to dig deeper to fully explain how this ends up in an
exception, maybe I'll do it tonight, but in the meantime here's some
context in case it helps.
It makes total sense. What doesn't make sense is the source of
helpers.rb to me:
https://github.com/rails/rails/blob/master/actionpack/lib/action_view/helpers.rb
First it should explicitly require (or require_dependency)
'active_support/autoload' and 'active_support/concern', right?
But then, why using autoload if you're just including all modules next?
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