rpc/rpcreflect: Add Value type.

rpc/rpcreflect: Add Value type.

This puts all the reflection calling logic into rpcreflect,
where it can be tested better and potentially be used by
other packages (for instance to test the API client without
an intervening marshaller)

https://code.launchpad.net/~rogpeppe/juju-core/412-rpc-caller/+merge/186910

Requires: https://code.launchpad.net/~rogpeppe/juju-core/411-rpc-introspection/+merge/186909

(do not edit description out of merge proposal)

[rog, 2013-09-23 10:10:44]

Please take a look.

[gz, 2013-09-23 17:53:36]

LGTM, the breakout does make the code a bit simpler I think. Would like William
or someone else reflective to have a look at this as well.

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/type.go
File rpc/rpcreflect/type.go (right):

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/type.go#newc...
rpc/rpcreflect/type.go:86: return nil
Wasn't immediately clear to me why checking for nil here was relevent, some
comment might be useful.

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/value.go
File rpc/rpcreflect/value.go (right):

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/value.go#new...
rpc/rpcreflect/value.go:68: return MethodCaller{}, fmt.Errorf("unknown object
type %q", rootMethodName)
So, Method always returns ErrMethodNotFound or nil, which is why this doesn't
care about the contents of err. Seems fair enough as discussed, given it's all
in the same package, and is not using the bool return 'ok' for api neatness
reasons.

[rog, 2013-09-24 07:12:54]

Please take a look.

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/type.go
File rpc/rpcreflect/type.go (right):

https://codereview.appspot.com/13778046/diff/9001/rpc/rpcreflect/type.go#newc...
rpc/rpcreflect/type.go:86: return nil
On 2013/09/23 17:53:36, gz wrote:
> Wasn't immediately clear to me why checking for nil here was relevent, some
> comment might be useful.

Done.

[fwereade, 2013-09-24 12:58:31]

LGTM, sorry, power cut out just as I'd finished earlier