code review 3889043: gob: do not encode or decode unexported fields

gob: do not encode or decode unexported fields
Such fields are simply ignored.

[r, 2011-01-11 21:17:39]

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

I'd like you to review this change.

[rsc1, 2011-01-11 21:28:30]

LGTM

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/codec_test.go
File src/pkg/gob/codec_test.go (right):

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/codec_test.go#newcod...
src/pkg/gob/codec_test.go:1340: if u1.c == u0.c {
u1.c != 0

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/doc.go
File src/pkg/gob/doc.go (right):

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/doc.go#newcode152
src/pkg/gob/doc.go:152: ArrayT  *arrayType
*ArrayType etc

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/encode.go
File src/pkg/gob/encode.go (right):

http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/encode.go#newcode545
src/pkg/gob/encode.go:545: op = nil
would be nice if this were "continue"
I'm not sure that fieldnum has to match the reflect struct type field numbers.

[r2, 2011-01-11 21:33:34]

> 
> http://codereview.appspot.com/3889043/diff/1/src/pkg/gob/encode.go#newcode545
> src/pkg/gob/encode.go:545: op = nil
> would be nice if this were "continue"
> I'm not sure that fieldnum has to match the reflect struct type field
> numbers.

in fact they do. that's how the encode machine iterates.

-rob

[rsc, 2011-01-11 21:43:44]

>> would be nice if this were "continue"
>> I'm not sure that fieldnum has to match the reflect struct type field
>> numbers.
>
> in fact they do. that's how the encode machine iterates.

right now encodeStruct skips over the fields with instr.op == nil.
i can't see that they get used anywhere else.
i think it's just historical that gob fieldnum == reflect fieldnum
in the implementation.  once the encode machine is built
i don't think it refers to reflect data structures at all.

[r, 2011-01-11 21:44:02]

*** Submitted as http://code.google.com/p/go/source/detail?r=0b072b98fa1b ***

gob: do not encode or decode unexported fields
Such fields are simply ignored.

R=rsc, r2
CC=golang-dev
http://codereview.appspot.com/3889043

[r2, 2011-01-11 21:45:22]

On Jan 11, 2011, at 1:43 PM, Russ Cox wrote:

>>> would be nice if this were "continue"
>>> I'm not sure that fieldnum has to match the reflect struct type field
>>> numbers.
>> 
>> in fact they do. that's how the encode machine iterates.
> 
> right now encodeStruct skips over the fields with instr.op == nil.
> i can't see that they get used anywhere else.
> i think it's just historical that gob fieldnum == reflect fieldnum
> in the implementation.  once the encode machine is built
> i don't think it refers to reflect data structures at all.

the == nil was a recent addition to maintain this fiction. i changed the code to
introduce a noop encoder and got rid of the nil.

but i investigate another approach.

-rob