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fix(scope): should allow removing listener during an event #695

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fix(scope): should allow removing listener during an event #695

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33 changes: 28 additions & 5 deletions lib/core/scope.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -736,6 +736,9 @@ class ScopeStream extends async.Stream<ScopeEvent> {
final _Streams _streams;
final String _name;
final subscriptions = <ScopeStreamSubscription>[];
bool _firing = false;
List<ScopeStreamSubscription> _toRemove;
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@pavelgj out of curiosity, why have you picked a lazy init here ? (the code could be simpler at the expense of some bytes)

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Trying to avoid unnecessary allocations to handle a corner case.

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would it be a good use case for introducing a getter ?

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The way I imagine a getter here it would also result in an unnecessary allocation when _remove is never called. How would you do it?

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You're absolutely right. I must be tired, I've just lost half a day fixing my ubuntu setup...



ScopeStream(this._streams, this._exceptionHandler, this._name);

Expand All @@ -750,16 +753,36 @@ class ScopeStream extends async.Stream<ScopeEvent> {
}

void _fire(ScopeEvent event) {
for (ScopeStreamSubscription subscription in subscriptions) {
try {
subscription._onData(event);
} catch (e, s) {
_exceptionHandler(e, s);
_firing = true;
try {
for (ScopeStreamSubscription subscription in subscriptions) {
try {
subscription._onData(event);
} catch (e, s) {
_exceptionHandler(e, s);
}
}
} finally {
_firing = false;
if (_toRemove != null) {
_toRemove.forEach(_actuallyRemove);
_toRemove = null;
}
}
}

void _remove(ScopeStreamSubscription subscription) {
if (_firing) {
if (_toRemove == null) {
_toRemove = [];
}
_toRemove.add(subscription);
} else {
_actuallyRemove(subscription);
}
}

void _actuallyRemove(ScopeStreamSubscription subscription) {
assert(subscription._scopeStream == this);
if (subscriptions.remove(subscription)) {
if (subscriptions.isEmpty) _streams._addCount(_name, -1);
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10 changes: 10 additions & 0 deletions test/core/scope_spec.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -654,6 +654,16 @@ void main() {
expect(args.length).toBe(4);
expect(args).toEqual(['do', 're', 'me', 'fa']);
}));

it('should allow removing listener during an event', inject((RootScope rootScope) {
StreamSubscription subscription;
subscription = rootScope.on('foo').listen((_) {
subscription.cancel();
});
expect(() {
rootScope.broadcast('foo');
}).not.toThrow();
}));
});
});
});
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