Merge lp://staging/~gary/juju-gui/fixDeltaFromChangeEdgeCase into lp://staging/juju-gui/experimental

Reviewers: mp+185053_code.launchpad.net,

Message:
Please take a look.

Description:
optimize and fix databinding.deltaFromChange

This is a grabbag of three small changes. The biggest change is that I
did some optimizations of databinding.deltaFromChange and fixed an edge
case (with test). I also optimized _setupDependencies for that edge
case, added some documentation about bindings (so I could refer to it
myself), and optimized the bind/_bind pair a bit by removing redundant
calls to code that iterates over all bindings (they are now done once in
bind, rather than once per viewlet in _bind).

https://code.launchpad.net/~gary/juju-gui/fixDeltaFromChangeEdgeCase/+merge/185053

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/13348056/

Affected files (+71, -29 lines):
   A [revision details]
   M app/views/databinding.js
   M test/test_databinding.js

Line-by-line comments for reviewers.

https://codereview.appspot.com/13348056/diff/1/app/views/databinding.js
File app/views/databinding.js (right):

https://codereview.appspot.com/13348056/diff/1/app/views/databinding.js#newcode186
app/views/databinding.js:186: var index = indexBindings(bindings, null,
true);
The "true" argument and then the "result.bindings.push.apply" below is
the real fix. All the other changes streamline the logic, resulting in
much fewer duplicate results and hopefully clearer reading.

https://codereview.appspot.com/13348056/diff/1/app/views/databinding.js#newcode393
app/views/databinding.js:393: this._modelChangeHandler();
These were moved from _bind, mostly as an optimization for reading but
also to prevent unnecessary duplication of work.

https://codereview.appspot.com/13348056/diff/1/app/views/databinding.js#newcode533
app/views/databinding.js:533: index[dep] = source;
This is just an optimization, so that if we have more than one of these
implicit bindings on the same source, we don't create multiple copies of
the source. It wasn't causing a bug, but this just makes it easier to
debug further downstream.

https://codereview.appspot.com/13348056/

*** Submitted:

optimize and fix databinding.deltaFromChange

This is a grabbag of three small changes. The biggest change is that I
did some optimizations of databinding.deltaFromChange and fixed an edge
case (with test). I also optimized _setupDependencies for that edge
case, added some documentation about bindings (so I could refer to it
myself), and optimized the bind/_bind pair a bit by removing redundant
calls to code that iterates over all bindings (they are now done once in
bind, rather than once per viewlet in _bind).

R=benji
CC=
https://codereview.appspot.com/13348056

https://codereview.appspot.com/13348056/