Alternate manifest using regexes to drive it

[jakobo]

Through conversation with @PeterFrueh, jquery's UI modules are difficult to load. In theory, we should be able to maintain the standard syntax:

$ = require("jQuery");
require("jquery.ui.core");
require("jquery.ui.mouse");
require("jquery.ui.widget");
require("jquery.ui.draggable");
// ... continue using $ normally

The limitations we are facing are best summed up as:

1. the jQuery UI objects look for jQuery in the global context. Because of require sandboxing, this isn't available by default. We could solve this by using the pointcuts syntax, but that yields issue 2 below
2. The current syntax doesn't allow for an easy way to package this up. You'd end up with a huge manifest, when really all you need is smarter regex rules

The result of this is a proposal for a new syntax that would deprecate require.manifest in favor of simpler additive rules

require.addRule(regex|string, [weight], {
  path: function() {} | string
  pointcuts: {
    before: function() {},
    after: function() {}
  }
});

[jakobo]

Some considerations:

• total time to run matches would be n regex/string checks
• if you find a match, do you abort early, or do you continue down the stack? On one hand, continuing down the stack is pretty powerful as far as matching rules go. On the other, that's a ton of overhead potentially.
• weight is listed as optional. Should faux-constants be created under require.CONSTANTS, or should we leave it up to the developer to weight their rules accordingly. By default, later rules would receive a higher index if not overridden.

[jakobo]

I pieced together a sample bit of code for what including jquery might look like. My biggest concern is the addRule still feels pretty unwieldy for the more robust examples. It's certainly better than having dozens of repeated code lines though for each jQuery UI module.

    require.setModuleRoot("http://localhost:4000/deps");
    require.addRule(/^jquery$/, "jquery-1.7.js");
    require.addRule(/jquery\.ui/, {
      path: function(module) {
        return ["jqueryui", module].join("/") + ".min.js"
      },
      pointcuts: {
        before: function() {
          var jQuery = require("jquery");
        }
        after: function() {
          module.setExports(jQuery);
        }
      }
    });