encoding/json: custom format for time.Duration

[wcn3]

Feature request:

JSON struct tags could be enhanced to provide the notion of time units since the parser
currently assumes everything is ns, causing workarounds of the type that may need to get
fixed, as in https://golang.org/cl/7086059

Sample code: http://play.golang.org/p/CZH9ThvhxK

What is the expected output?
&{Access:12345 Refresh:23456 ExpiresIn:1h0m0s ValidIn:1.234us}
2013-01-21 22:37:40.646947673 -0800 PST
2013-01-21 23:37:40.647083585 -0800 PST

What do you see instead?
&{Access:12345 Refresh:23456 ExpiresIn:3.6us ValidIn:1.234us}
2009-11-10 23:00:00 +0000 UTC
2009-11-10 23:00:00.0000036 +0000 UTC

[wcn3]

Comment 1:

Updated proposed syntax in http://play.golang.org/p/LHuEhLVmTt to matchkey-value
encoding used in protobuf struct tags. http://play.golang.org/p/LHuEhLVmTt

[wcn3]

Comment 2:

Updated proposed syntax to match key-value encoding used in protobuf package.
http://play.golang.org/p/LHuEhLVmTt

[rsc]

Comment 3:

Not for Go 1.1.

Labels changed: removed go1.1.

[rsc]

Comment 4:

Labels changed: added priority-later, removed priority-triage.

Status changed to Thinking.

[rsc]

Comment 5:

It is unclear to me whether we can do this.
Go 1.1 programs would not be able to read the Go 1.2 encoding,
although we could make Go 1.2 programs able to read the Go 1.1 encoding.
It's not that encoding/json is assuming nanoseconds, it's that it's treating the
Duration as a simple int64.

Labels changed: added go1.2maybe.

[rsc]

Comment 6:

Labels changed: added feature.

[robpike]

Comment 7:

I don't think we can do this. It won't be in 1.2 in any case.

Labels changed: added go1.3maybe, removed go1.2maybe.

[robpike]

Comment 8:

Labels changed: removed go1.3maybe.

[rsc]

Comment 9:

Labels changed: added go1.3maybe.

[rsc]

Comment 10:

Labels changed: removed feature.

[rsc]

Comment 11:

Labels changed: added release-none, removed go1.3maybe.

[rsc]

Comment 12:

Labels changed: added repo-main.