On 4/22/2014 5:55 AM, Gijs Kruitbosch wrote:
On 22/04/2014 05:24, Joshua Cranmer 🐧 wrote:
For more specific explanation then:
I have a (non-negotiably) JS-implemented XPCOM service called the Folder
Lookup Service. I want to add an API to it called getOrCreateFolder that
returns a Promise<nsIMsgFolder>. I have non-negotiable C++ code that
wants to call this method, and do something when the promise is resolved
or rejected.
Dumb question time: why not provide an XPIDL'd alternative JS wrapper
method (getOrCreateFolderForNativeConsumers or whatever) that takes
two nsIRunnables or equivalent XPIDL'd C++ callback wrappers, and
wrapping the getOrCreateFolder method with
.then((x) => successRunnable.run(x), (x) => failRunnable.run(x));
That's certainly possible, but, as my reviewer commented, if we want to
start using promises a lot more in the API, it makes more sense to try
to find a better solution now rather than proliferate ad-hoc solutions
all over the place (the current state of the art is to stuff the thing
being processed into a URL and use an nsIUrlListener, which doesn't work
quite so well if the object isn't really a URL in the first place).
--
Joshua Cranmer
Thunderbird and DXR developer
Source code archæologist
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