Help with removing __iterator__ from JS

David Rajchenbach-Teller dteller at
Tue Jul 21 11:22:02 UTC 2015

If I recall correctly, the difficulty with the OS.File removal is that
some clients of this code were taking advantage of the old API in ways
that do not match the new one. I will try and take another look at it
over the summer.


On 21/07/15 13:07, Tom Schuster wrote:
> Hello!
> We have an old JS extension that allows objects to modify how they
> behave when used with for-in. However this extension will never make it
> into ES6 and is actually incompatible with how iteration is defined
> there. So please don't use __iterator__anymore.
> I would really appreciate your help with removing __iterator__ from the
> OS.File interface, which makes very heavy use of this feature. Bug
> 938704 hasn't seen any serious work since 2013.
> We also need to look into the addon-sdk, where many of the custom
> collection types implement __iterator__ and thus addon authors might
> iterate over them with for-in ...
> Aside: Please also try avoid using Iterator().
> Thank you,
> Tom
> _______________________________________________
> firefox-dev mailing list
> firefox-dev at

David Rajchenbach-Teller, PhD
 Performance Team, Mozilla

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