Erector Page base class.

Allows for accumulation of script and style tags (see example below) with either external or inline content. External references are 'uniq'd, so it's a good idea to declare a js script in all widgets that use it, so you don't accidentally lose the script if you remove the one widget that happened to declare it.

The script and style declarations are accumulated at class load time, as 'dependencies'. This technique allows all widgets to add their own requirements to the page header without extra logic for declaring which pages include which nested widgets. Fortunately, Page is now smart enough to figure out which widgets were actually rendered during the #body_content run, so it only emits into its HEAD the dependencies that are relevant. If it misses some, or if you want to add some extra dependencies – for instance, styles that apply to widgets that are rendered later via AJAX – then return an array of those widget classes in your subclass by overriding the extra_widgets method.

If you want something to show up in the headers for just one page type (subclass), then override head_content, call super, and then emit it yourself.

Body content can be supplied in several ways:

* In a Page subclass, by overriding the #body_content method:

   class MyPage < Erector::Widgets::Page
     def body_content
       text "body content"
     end
   end

* Or by overriding #content and passing a block to super:

   class MyPage < Erector::Widgets::Page
     def content
       super do
         text "body content"
       end
     end
   end

* Or by passing a block to Page.new:

   Erector::Widgets::Page.new do
     text "body content"
   end

This last trick (passing a block to Page.new) works because Page is an InlineWidget so its block is evaluated in the context of the newly instantiated widget object, and not in the context of its caller. But this means you can't access instance variables of the caller, e.g.

@name = "fred"
Erector::Widgets::Page.new do
  text "my name is #{@name}"
end

will emit “my name is ” because @name is nil inside the new Page. However, you can call methods in the parent class, thanks to some method_missing magic. Confused? You should be. See Erector::Inline#content for more documentation.

Author

Alex Chaffee, alex@stinky.com

Example Usage:

class MyPage < Page
  external :js, "lib/jquery.js"
  external :script, "$(document).ready(function(){...});"
  external :css, "stuff.css"
  external :style, "li.foo { color: red; }"

  def page_title
    "my app"
  end

  def body_content
    h1 "My App"
    p "welcome to my app"
    widget WidgetWithExternalStyle
  end
end

class WidgetWithExternalStyle < Erector::Widget
  external :style, "div.custom { border: 2px solid green; }"

  def content
    div :class => "custom" do
      text "green is good"
    end
  end
end

Thoughts:

* It may be desirable to unify #js and #script, and #css and #style, and
  have the routine be smart enough to analyze its parameter to decide
  whether to make it a file or a script.