encoding/json: a way for MarshalJSON to skip marshaling a field?

[minux]

for example, one might want to solve issue #4357 with this.

a test program: http://play.golang.org/p/gyk1yehoTp

i think we can treat a nil byte slice as the signal.

[dsymonds]

Comment 1:

issue #4357 is for this, via an explicit IsZero and using omitempty.

Status changed to Duplicate.

Merged into issue #4357.

[minux]

Comment 2:

i don't think this is duplicate of issue #4357, because custom JSONMarshaler still need
a way to skip marshaling the field (sort of IsZero and JSONMarshal combined).
I'm just using issue #4357 as an example.

[dsymonds]

Comment 3:

There's no JSON field types that can omit themselves without
omitempty. Either you're proposing to add such a mechanism, or these
two proposals are equivalent.

[minux]

Comment 4:

yeah, i propose to allow MarshalJSON to return a nil byte slice to
signify omitting this field. WDYT?

[dsymonds]

Comment 5:

It seems like a bad idea to conflate them. Go typically doesn't use
sentinels. I think the IsZero approach is much clearer, plus you get
the benefit of being able to control the omission with omitempty.

[minux]

Comment 6:

you're right. thank you for explanations.