[jboss-dev-forums] [Design the new POJO MicroContainer] - Internal AbstractController State

[adrian@jboss.org]

I can see having the abstract controller state protected is a bit dangerous
given the recent changes for the Scoped Kernels.

So I've changed all the state to private with documented protected methods
for subclasses to use.

The reason I say it is dangerous is because there is more to updating a context's
state than allContexts. There are other "indexes" where the context could exist.

Besides this new api looks wrong to me anyway, I documented it in a TODO

  |    // TODO This api looks broken and unsafe
  |    //      1) It should not be public
  |    //      2) There should be parameter checking for public methods
  |    //      3) There should be locking when updating state
  |    //      4) Error handling?
  |    public void addControllerContext(ControllerContext context)
  | 

The way to make more dangerous operations available to subclasses
would be through some helper class that is only protected accesible.

e.g.

  | 
  | private UnsafeInterface unsafe = new UnsafeImplementation();
  | 
  | protected UnsafeInterface getUnsafe()
  | {
  |    return unsafe;
  | }
  | 
  | protected interface UnsafeInterface
  | {
  |    // Methods intended for subclasses that know what they are doing here
  |    // Properly documented to explain requirements, e.g. locking
  | }
  | 
  | private class UnsafeImplementation implements UnsafeInterface
  | {
  |    // Implementation of potentially unsafe methods, but still does some checking
  |    // like null parameters or reasonable error handling so we don't end up
  |    // with a subclass breaking the whole system.
  | }
  | 

There is a similar trick that is the reverse where you define a wrapper interface
that only exposes safe methods and make the real implementation
unreachable (you always hand out the wrapper externally).

View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4034065#4034065

Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&p=4034065