Allow hidden properties and implement GetIdentityHash

- Allow hidden properties to be set on any JSObject through the V8 C++ API.
- Use the hidden properties to expose a IdentityHash accessor.


Committed: http://code.google.com/p/v8/source/detail?r=1550

[iposva, 2009-03-19 17:31:05]

This change list does not expose the hidden properties into JavaScript in any
way. This is an update from the previous revision sent out for review.
This is a new change list because I moved machines. I will close the old one
once this has been reviewed.

[Kasper Lund, 2009-03-19 17:46:03]

LGTM.

http://codereview.chromium.org/50016/diff/1/2
File test/cctest/test-api.cc (right):

http://codereview.chromium.org/50016/diff/1/2#newcode1267
Line 1267: CHECK_NE(hash, hash2);
Is this really guaranteed? Freaky.

http://codereview.chromium.org/50016/diff/1/2#newcode1270
Line 1270: CHECK_NE(hash, hash3);
Again.

[iposva, 2009-03-19 18:12:10]

http://codereview.chromium.org/50016/diff/1/2
File test/cctest/test-api.cc (right):

http://codereview.chromium.org/50016/diff/1/2#newcode1267
Line 1267: CHECK_NE(hash, hash2);
On 2009/03/19 17:46:03, Kasper Lund wrote:
> Is this really guaranteed? Freaky.
I will add a comment that if two consecutive objects get the same identity hash
then it might be a good time to look at your random number generator.

[Mads Ager (chromium), 2009-03-19 18:21:43]

LGTM

http://codereview.chromium.org/50016/diff/1/3
File include/v8.h (right):

http://codereview.chromium.org/50016/diff/1/3#newcode1080
Line 1080: * Returns the identity hash for this object.
We should state in the API that one of the hidden value keys is used by this
call (the potential for conflict is low, but we should document it).

[iposva, 2009-03-19 18:39:13]

http://codereview.chromium.org/50016/diff/1/3
File include/v8.h (right):

http://codereview.chromium.org/50016/diff/1/3#newcode1080
Line 1080: * Returns the identity hash for this object.
On 2009/03/19 18:21:44, Mads Ager wrote:
> We should state in the API that one of the hidden value keys is used by this
> call (the potential for conflict is low, but we should document it).
I will add a comment to the hidden properties that all hidden properties
introduced by V8 internally will be prefixed with "v8::" to reduce the potential
for conflicts.