Registering C++ objects in QML
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Wow this escalated quickly!
I think the fork is a good idea, tbh.
@kshegunov said in Registering C++ objects in QML:
I continue to claim that a "singleton" is nothing more than a glorified global variable, so it should be treated exactly as such - a bad monstrously stupid idea in 99.999% of cases!
sadly, in combination with QML your options are limited. If you want to access the class from cpp and QML you can do one of the following
- Singleton, instance in cpp and exactly where you need it in qml
- Normal instance in cpp, a global property accessible in all qml files
- using find child to search for your qml item and do the connect in cpp. This falls apart as soon as you start to dynamically load your qml files
So, Pest Cholera, or Malaria.
@stehlo said in Registering C++ objects in QML:
Without going into extra detail which would detract from the main point, the attempt to deleteLater the QObject unnaturally at the point of the application being aboutToQuit causes either of the two following fatal errors, depending on whether we do this for the networking singleton or the database one:
QObject: shared QObject was deleted directly. The program is malformed and may crash.
abort_message: assertion "Pure virtual function called!" failed
Fatal signal 6 (SIGABRT), Abortedor
null pointer dereference
Fatal signal 11 (SIGSEGV), Segmentation faultThe attempt to deleteLater is happening either too early or two late.
I actually have to disagree.
after reading the post by @Chris-Kawa I changed my own project to include the about to quit cleanup. That's for about 10 Singletons not once did I have one of your errors mentions above.I would say there's still something going on that causes your issue, but I think it's user -rather than framework related
@j-hilk said in Registering C++ objects in QML:
Normal instance in cpp, a global property accessible in all qml files
What I wrote. Normal object in C++, a context property in QML. Which is kind of the point of having context properties to begin with, is it not?
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@j-hilk said in Registering C++ objects in QML:
Normal instance in cpp, a global property accessible in all qml files
What I wrote. Normal object in C++, a context property in QML. Which is kind of the point of having context properties to begin with, is it not?
@kshegunov yes, and also the reason why I think the Singleton is the lesser of 2 evils, as it's not globally accessible in all Files but has to be explicitly imported inside the File.
Wouldn't you agree 😉
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