KAYLukas
commented
10 years ago Does not seem possible:
- defining the interface with a unique number is hard
- The current syntaxis has no difference from the instance syntaxis, only way to differentiate between interface and non-interface would be to use the sizeof which is not preprocessor-time, and thus the instance call would give compilation errors.
We need to introduce a new syntaxis: foxy((n via INode) $ getRootNode()); We don't use the 'as' keyword as it does not prevent method hiding, which we want to make explicit. we could also allow binding instance methods to different interface methods, making an interface something more than just an 'abstract' class with multiple inheritance.
As we cannot achieve multiple inheritance (atleast not both as function and as properties) we want to implement interfaces: a set of predefined functions which are assumed to be located in the class.
We want to do something alike:
As each class can implement multiple interfaces, we have no way of addressing the right function pointer in
n->class. Also as we cannot retrieve the typename of n, we cannot do something liken->class->INode->getRootNode().The proposed workaround is rather ugly (even for our current hacking code), but should work:
Each interface struct will never be instantiated, object will only be casted towards them (which is actually a mismatching cast), and as interface do not have any properties (except for the class property), this is not really problematic.
As each interface struct is never instantiated, we can do everything with the body.
The sizeof operator is evaluated at compiletime and is always the same for the same type
A solution would be to give each interface a unique size and use this size to associate a interface with the vtable in the class of the object. Unique sizes could be defined by using COUNTER, but a problem with this approach is, that this size is only object wide (.o) and not link wide unique, i.e. different objects will assume the struct will have different sizes. This would somehow require a object local mapping from struct to class, which is unknown if this is possible. A fallback would be to interpret the call string, but this is terrible slow, and not a real solution.