Oh, and from C++, there's also now a range iterator wrapper with
similar semantics:
for (auto& docShell : SimpleEnumerator<nsIDocShell>(docShellEnum)) {
...
}
On Thu, Aug 23, 2018 at 03:19:55PM -0700, Kris Maglione wrote:
As of bug 1484496, any C++-implemented nsISimpleEnumertor instance can
be used as a JS iterator. And, when used this way, the iterators now
have intrinsic type information, and therefore do not require QIing
their elements.
Which is to say, now you can simply do:
for (let window of Services.wm.getEnumerator("navigator:browser")) {
...;
}
for (let docShell of docShellEnum) {
...;
}
rather than:
let winEnum = Services.wm.getEnumerator("navigator:browser");
while (winEnum.hasMoreElements()) {
let window = winEnum.getNext();
...
}
while (docShellEnum.hasMoreElements()) {
let docShell = winEnum.getNext().QueryInterface(Ci.nsIDocShell);
...
}
If you happen to be using an nsIArray from directly from JavaScript,
you unfortunately still need to specify the expected types, since
nsIArray has no idea what types it can contain:
for (let thing of array.enumerate(Ci.nsIThing)) {
...
}
Aside from being easier to maintain, these forms should also be
somewhat faster than the old protocol, since they only require one
XPConnect call per iteration rather than 3(+).
-Kris
--
Kris Maglione
Senior Firefox Add-ons Engineer
Mozilla Corporation
There is no greater mistake than the hasty conclusion that opinions
are worthless because they are badly argued.
--Thomas Huxley
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