Hi list. This is my first time posting here, so bare with me if I'm being an idiot. I apologize for continuing with the performance discussion but I've noticed unintuitive (at least to me) behaviour when using interfaces in Vala. I know that calling interface methods is expensive and that it's a known issue in GLib but there is another problem. When a class implements an interface, calling methods is slow regardless whether you declare your objects as being instances of the class or the interface. I attached a simple example that demonstrates the problem. Object1 implements the interface directly and it doesn't matter whether we declare our object as Interface or Object1, both are slow. Object1 through interface : 18.620215 Object1 directly : 18.767607 Object2 does not implement Interface directly but inherits form AbsObject (which in this case is abstract but it could also be a regular class). which in turn implements Interface, now only the instance declared as Interface is slower. Object2 through interface : 18.902430 Object2 directly : 2.987541 Looking at the generated C code it seems to be a side effect of the way vala handles inheritance but I don't have enough experience with GObject to judge. So my question would be whether this is intentional, maybe I'm missing something? If it is then interfaces have to be used even more carefully and you need to use a dummy class in between the interface just to be able to use your class without the extra overhead when the interface is not needed. Regards, Sergej
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interface-test.vala
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