code review 14190044: encoding/json: add an example for RawMessage

encoding/json: add an example for RawMessage

RawMessage is useful and mildly non-obvious.
Given the frequency with which RawMessage questions
show up on golang-nuts, and get answered with an example,
I suspect adding an example to the docs might help.

[josharian, 2013-10-01 19:33:17]

Hello golang-dev@googlegroups.com,

I'd like you to review this change to
https://code.google.com/p/go

[adg, 2013-10-02 05:07:11]

Thanks for thsi.

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
File src/pkg/encoding/json/example_test.go (right):

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:114: switch c.Space {
this could be

var dst interface{}
switch c.Space {
case "RGB":
  dst = new(RGB)
case "YCbCr":
  dst = new(YCbCr)
}
err := json.Unmarshal(c.Point, dst)
...
fmt.Println(dst)

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:119: fmt.Println("error:", err)
we typically use log.Fatal in examples, so you can lose the return

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:122: fmt.Println(point)
i wonder if there's something more interesting you can do, rather than just
print the color. hm

[josharian, 2013-10-02 15:33:00]

Hello golang-dev@googlegroups.com, adg@golang.org (cc:
golang-dev@googlegroups.com),

Please take another look.

[josharian, 2013-10-02 15:34:42]

Oops, I expected these comments would also get sent when I ran `hg mail`. I
continue to fail at Rietveld, sigh. :/

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
File src/pkg/encoding/json/example_test.go (right):

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:114: switch c.Space {
On 2013/10/02 05:07:11, adg wrote:
> this could be
> 
> var dst interface{}
> switch c.Space {
> case "RGB":
>   dst = new(RGB)
> case "YCbCr":
>   dst = new(YCbCr)
> }
> err := json.Unmarshal(c.Point, dst)
> ...
> fmt.Println(dst)

Thanks, that's much better. Done.

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:119: fmt.Println("error:", err)
On 2013/10/02 05:07:11, adg wrote:
> we typically use log.Fatal in examples, so you can lose the return

Done.

https://codereview.appspot.com/14190044/diff/6001/src/pkg/encoding/json/examp...
src/pkg/encoding/json/example_test.go:122: fmt.Println(point)
On 2013/10/02 05:07:11, adg wrote:
> i wonder if there's something more interesting you can do, rather than just
> print the color. hm

I thought about using cuter examples (historical events of different types), but
it made an already long example even longer. I also wanted to print the type, a
la:

	fmt.Printf("%#v\n", dst)

but the output for it was a bit ugly:

	&json_test.YCbCr{Y:0xff, Cb:0, Cr:-10}
	&json_test.RGB{R:0x62, G:0xda, B:0xff}

I'd love other suggestions, though -- the existing output is decidedly boring.

[adg, 2013-10-02 22:51:41]

LGTM

Boring is OK. :-)

[adg, 2013-10-02 22:52:30]

*** Submitted as https://code.google.com/p/go/source/detail?r=f14c05d8145f ***

encoding/json: add an example for RawMessage

RawMessage is useful and mildly non-obvious.
Given the frequency with which RawMessage questions
show up on golang-nuts, and get answered with an example,
I suspect adding an example to the docs might help.

R=golang-dev, adg
CC=golang-dev
https://codereview.appspot.com/14190044

Committer: Andrew Gerrand <adg@golang.org>