Implement #484 : hookState

[fabien]

This implements #484

[fabien]

@bajtos @raymondfeng thoughts?

[bajtos]

@raymondfeng @ritch If you have any objections against hookState, then speak now. Otherwise I'll review and land this PR later today/early tomorrow CET.

[bajtos]

coding style: please move the context initialisation to a new line and property.

var context = ...;
Model.notifyObserversOf('before save', context, function(err) {

The same fix should be applied to all other places where the context initialization does not fit a single line.

IIRC, we are already using the style described above in other existing code, so let's keep the style consistent.

[fabien]

OK.

[fabien]

@bajtos I'm running out of time here, with zero progress today (and lost work from yesterday).

I moved ahead with #486 - how I can I make sure I don't have to redo that?

[fabien]

@bajtos reformatted and fixed - except for hookState.test, which should remain - perhaps be renamed, but otherwise is required to test all hooks.

[ritch]

No qualms here. Just a reminder that we need an example for this.

[raymondfeng]

LGTM.

[fabien]

OK, can anyone merge then please?

[bajtos]

I am very unhappy about this merge, since when do we prefer quick merges at the cost of code quality? The code coverage is low, the fact that the state is shared between hooks is tested only for before/after delete hooks. The technique using hookState.test is too magic, it will be difficult to understand for anybody not familiar with this pull request (including us in few months) and it makes the future maintenance more difficult.