The Angular circular dependancy error https://docs.angularjs.org/error/$injector/cdep results from services with injected dependencies A <- B <- A.

There are ways to circumvent this error. This one http://clintberry.com/2013/modular-angularjs-application-design/ uses a main module with all sub modules directlyinjected in to it.

Creating a “MainAppModule” allows us to inject all our other 
modules which in turn allows each of our other modules to 
access each other. So if the Reports module needs to access 
something from the Patient module, it will be able to with 
this method without having to inject the Patient module 
directly into the Reports module.

From http://stackoverflow.com/questions/19344214/problems-with-circular-dependency-and-oop-in-angularjs A circular dependency is a the sign of mixing of concerns, which is a really bad thing."

• http://misko.hevery.com/2008/08/01/circular-dependency-in-constructors-and-dependency-injection/

The publish-subscribe pattern provide a way to loosely couple modules.

• https://en.wikipedia.org/wiki/Publish%E2%80%93subscribe_pattern

Angular provide the broadcast and listener mechanism to implement this pattern.

• http://codingsmackdown.tv/blog/2013/04/29/hailing-all-frequencies-communicating-in-angularjs-with-the-pubsub-design-pattern/

• http://eburley.github.io/2013/01/31/angularjs-watch-pub-sub-best-practices.html

• http://jsfiddle.net/eburley/N2yUF/

• http://toddmotto.com/all-about-angulars-emit-broadcast-on-publish-subscribing/

When to use a watch:

• when you're writing a directive and want data binding behavior
• when you're watching a stateful service
• when it's OK for the ui and state update to happen in a non-deterministic order

When NOT to use a watch:

• when you need to orchestrate complicated data loading patterns
• when you're watching the routeParams.