The correct way to use any one of the rails pieces is to require the
framework file first.

You have to do

require 'action_view' # this file only loads what is needed to use the
framework inside and outside the rails scoperequire
'action_view/helpers'


Rafael Mendonça França
http://twitter.com/rafaelfranca
https://github.com/rafaelfranca


On Fri, Feb 8, 2013 at 3:46 PM, Rodrigo Rosenfeld Rosas
<[email protected]>wrote:

>  I know it is tangential. I was just explaining why I don't agree with the
> current approach because non Rails code could rely only on
> 'action_view/helpers', don't you agree? How are they supposed to know that
> they should first require 'active_support/rails' or any other entry point?
>
> I don't think it is fine to just assume that ActionView classes only make
> sense in within the Rails context. This is an unsafe assumption that I
> don't agree with.
>
> Em 08-02-2013 15:42, Xavier Noria escreveu:
>
> I am only explaining why autoload and concern have no explicit requires in
> that file. That was a tangential question you did not directly related to
> the exception.
>
> Sent from my iPhone
>
> On 08/02/2013, at 18:36, Rodrigo Rosenfeld Rosas <[email protected]>
> wrote:
>
>   I don't understand what you mean. In my unit tests involving
> ParseFormatUtils for instance Rails is never loaded and my application
> doesn't even use ActiveRecord.
>
> But my tests weren't complaining anyway because they don't autoload
> ActionView/Helpers.
>
> Also, even if I explicitly required as/rails it wouldn't fix the situation
> for my case.
>
> This is what's happening in a simplified way:
>
>
> ./test.rb:
> autoload :A, 'a'
> require 'a/b'
>
> ./lib/a.rb:
> module A
>   autoload :B, 'a/b'
>   include B
> end
>
> ./lib/a/b.rb:
> module A
>   module B
>   end
> end
>
> ruby -I lib test.rb
>
>
> This is enough to create the circular dependency error. Maybe this is one
> of the reasons why Matz wants to remove autoload from Ruby...
>
> Sorry but I don't have any suggestions right now that would make require
> 'a/b' work if 'a' is set to be autoloaded and 'a' requires 'b' which
> depends on 'a'...
>
> Unless we create some 'action_view/helpers/all.rb'  file. Would that be
> acceptable?
>
> Best,
> Rodrigo.
>
> Em 08-02-2013 15:26, Xavier Noria escreveu:
>
> No, no, as/rails.rb is already required by the entry point
> of every component (except AS). That is a given in the
> context of a Rails application, and
>
>      gem 'active_record'
>
>  does that if standalone.
>
>  Sent from my iPhone
>
> On 08/02/2013, at 18:12, Rodrigo Rosenfeld Rosas <[email protected]>
> wrote:
>
>   Em 08-02-2013 15:00, Xavier Noria escreveu:
>
> Some very common files are loaded at the entry point of every component,
> to avoid repeating their require again and again:
>
>
> https://github.com/rails/rails/blob/master/activesupport/lib/active_support/rails.rb
>
>
> But shouldn't helpers.rb require 'active_support/rails' then instead of
> just 'active_support/benchmarkable'?
>
> Otherwise it should be documented that we're not supposed to require
> specific parts of some libraries included in Rails... That way I'd know
> (although surprised) that I'm not supposed to require
> 'action_view/helpers/number_helper' but simply 'action_view/helpers' (or
> just 'action_view'?)
>
>
>  As for the autoload + include, I don't really know, maybe it is a fancy
> way to avoid writing a file path. Seems unnecessary to me at first glance.
> Maybe someone else from the team has a better justification?
>
> Sent from my iPhone
>
> On 08/02/2013, at 17:45, Rodrigo Rosenfeld Rosas <[email protected]>
> wrote:
>
>   Em 08-02-2013 13:03, Xavier Noria escreveu:
>
> On Fri, Feb 8, 2013 at 3:18 PM, Rodrigo Rosenfeld Rosas<[email protected]> 
> <[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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