Le 09/05/2014 08:50, Tom Van Cutsem a écrit :
Rick,
It's true that allowing user-invented custom attributes will not break
any important existing invariants (except perhaps that all existing
descriptors can be assumed not to have any own properties besides the
standard attributes. Existing code may depend on that, although it
feels highly unlikely).
Just to try to assess the unlikelihood and understand the cases where a
ES5 code expectations aren't met:
The only case where ES6 and ES5 may diverge is for
Object.getOwnPropertyDescriptor where a Proxy may return something that
cannot be expected from any ES5 object.
The after-trap completes the property descriptor (and when completing
picks specifically only data or accessor property), so code that expects
a complete property descriptor cannot be broken.
However, a divergence may only occur if, for instance, the code loops
over the property descriptor properties or expects exactly 4 properties.
Is that correct or am I missing cases?
David
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