Assertion failure in EventDispatcher::TriggerEvents

[viciious]

The following line produces an assertion failure in debug build in MSVC:

	for (auto it = begin; it != end; ++it)

Further down the stack:

	_Vector_const_iterator& operator++()
		{	// preincrement
 #if _ITERATOR_DEBUG_LEVEL != 0
		const auto _Mycont = static_cast<const _Myvec *>(this->_Getcont());
		_STL_VERIFY(_Ptr, "can't increment value-initialized vector iterator");
		_STL_VERIFY(_Ptr < _Mycont->_Mylast, "can't increment vector iterator past end");
 #endif /* _ITERATOR_DEBUG_LEVEL != 0 */

The _Mycont pointer is null

[viciious]

In this particular case, a button click event hides the document which triggers another event, in which a listener de-attaches itself right in the ProcessEvent call and that confuses the iterator.

[viciious]

Changing the loop to read:

	for (auto it = begin, next = end; it != end; it = next)
	{
		next = std::next(it, 1);
		it->listener->ProcessEvent(event);
	}

fixes the assertion failure :)

[mikke89]

Yeah, I think the problem is that when adding or removing listeners, the iterators will be invalidated. Could you test the changes I committed?
The commit should help avoid invalidated iterators, but may result in a skip or repeat of a listener invocation.

[viciious]

I think the best solution here would be to copy the slice of the original array to a temporary array and iterate over that.

[mikke89]

Okay, I guess I'm fine with the approach, at least until I see any real-world problems with it :)