Add Delta and MarshalJSON for megawatcher

Add Delta and MarshalJSON for megawatcher

This code is largely from Roger, with tests from Benji and me.  This simply
adds a Delta object that can marshal in the same way as PyJuju.  It includes
stubs for the four types of entity information we should need.

https://code.launchpad.net/~gary/juju-core/megawatcher_delta/+merge/151821

(do not edit description out of merge proposal)

[gary.poster, 2013-03-05 19:00:40]

Please take a look.

[dimitern, 2013-03-05 19:06:57]

LGTM, just a couple of trivials.

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go
File state/megawatcher.go (right):

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode13
state/megawatcher.go:13: Remove bool
s/Remove/Removed/ ?

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode18
state/megawatcher.go:18: func (d *Delta) MarshalJSON() ([]byte, error) {
doc comment?

[rog, 2013-03-05 20:26:29]

LGTM

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go
File state/megawatcher.go (right):

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode13
state/megawatcher.go:13: Remove bool
On 2013/03/05 19:06:57, dimitern wrote:
> s/Remove/Removed/ ?

depends whether you think of the delta as a description of what has happened, or
an instruction to the consumer of the delta. i think both are valid
perspectives. i'll leave the choice up to the proposers.

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode13
state/megawatcher.go:13: Remove bool
On 2013/03/05 19:06:57, dimitern wrote:
> s/Remove/Removed/ ?

depends whether you think of the delta as a description of what has happened, or
an instruction to the consumer of the delta. i think both are valid
perspectives. i'll leave the choice up to the proposers.

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode18
state/megawatcher.go:18: func (d *Delta) MarshalJSON() ([]byte, error) {
On 2013/03/05 19:06:57, dimitern wrote:
> doc comment?

perhaps:
// MarshalJSON implements json.Unmarshaller.

[gary.poster, 2013-03-06 03:29:28]

Thank you!

Gary

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go
File state/megawatcher.go (right):

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode13
state/megawatcher.go:13: Remove bool
On 2013/03/05 19:06:57, dimitern wrote:
> s/Remove/Removed/ ?

Done.

https://codereview.appspot.com/7488043/diff/1/state/megawatcher.go#newcode18
state/megawatcher.go:18: func (d *Delta) MarshalJSON() ([]byte, error) {
On 2013/03/05 19:06:57, dimitern wrote:
> doc comment?

Done.

[gary.poster, 2013-03-06 13:20:28]

*** Submitted:

Add Delta and MarshalJSON for megawatcher

This code is largely from Roger, with tests from Benji and me.  This simply
adds a Delta object that can marshal in the same way as PyJuju.  It includes
stubs for the four types of entity information we should need.

R=dimitern, rog
CC=
https://codereview.appspot.com/7488043