returns in predicates no longer supported

[coldnebo]

A side effect of the fix for issue 1 is that blocks that use return generate a LocalJumpError now. Since predicates are conceptually like lambdas, it's much more flexible to support return within predicate blocks -- especially when transplanting business logic from legacy sources that may be hard to refactor into a non-return format.

For example:

# in a controller action...
predicate(:show_secret?) { 
  if my_terrible_secret
    return true
  else
    return false
  end 
}

# then, when used in the view...
Started GET "/main/index" for 127.0.0.1 at 2012-06-14 18:13:07 -0400
Connecting to database specified by database.yml
Processing by MainController#index as HTML
  Rendered main/index.html.erb within layouts/application (9.0ms)
Completed 500 Internal Server Error in 74ms

ActionView::Template::Error (unexpected return):
    1: <h1>Main#index</h1>
    2: <p>Find me in app/views/main/index.html.erb</p>
    3: <% if show_secret? %>
    4: <p>THIS IS THE SECRET BLOCK</p>
    5: <% end %>
  app/controllers/main_controller.rb:8:in `block in index'
  app/views/main/index.html.erb:3:in `_app_views_main_index_html_erb___2806522044999392377_25110420'

  Rendered /local/rvm/gems/ruby-1.9.3-p194@conditest/gems/actionpack-3.2.6/lib/action_dispatch/middleware/templates/rescues/_trace.erb (19.2ms)
  Rendered /local/rvm/gems/ruby-1.9.3-p194@conditest/gems/actionpack-3.2.6/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (0.9ms)
  Rendered /local/rvm/gems/ruby-1.9.3-p194@conditest/gems/actionpack-3.2.6/lib/action_dispatch/middleware/templates/rescues/template_error.erb within rescues/layout (30.5ms)
[2012-06-14 18:13:08] WARN  Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true

[coldnebo]

This fix was a little harder to get right. It turns out that define_method(name,&block) has special magic that keeps block as a method/lambda if it is so inclined, while define_method(name) {} always creates a new Proc. (This is why condi-0.0.6 worked and 0.0.7 didn't.) So I had to switch strategies and define an impl the old way, while wrapping it the new way with the request id check logic. Phew!

Anyway, cooking with gas now:

Started GET "/main/index" for 127.0.0.1 at 2012-06-14 19:46:02 -0400
Connecting to database specified by database.yml
Processing by MainController#index as HTML
  Rendered main/index.html.erb within layouts/application (2.9ms)
Completed 200 OK in 164ms (Views: 160.8ms | ActiveRecord: 0.0ms)