I am trying to wrap a function which is used to cast to another type.
The C++ example is:
++
Handle(Geom_Point) aPnt1;
Handle(Geom_CartesianPoint) aPnt2, aPnt3;
aPnt2 = new Geom_CartesianPoint();
aPnt1 = aPnt2; // OK, standard assignment
aPnt3 = Handle(Geom_CartesianPoint)::DownCast (aPnt1);
// OK, the actual type of aPnt1 is Geom_CartesianPoint, although the static
type of the handle is Geom_Point
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where `Geom_CartesianPoint` inherits from `Geom_Point`. And `Handle` is some
form of smart pointer. (Sorry, if the terminology is not correct, since I am
not a pro).
In the header file, there are two functions defined as follows:
++
//! Down casting operator from handle to base type
template <class T2>
static typename opencascade::std::enable_if<is_base_but_not_same<T2,
T>::value, handle>::type
DownCast (const handle<T2>& theObject)
{
return handle (dynamic_cast<T*>(const_cast<T2*>(theObject.get())));
}
//! Down casting operator from pointer to base type
template <class T2>
static typename opencascade::std::enable_if<is_base_but_not_same<T2,
T>::value, handle>::type
DownCast (const T2* thePtr)
{
return handle (dynamic_cast<T*>(const_cast<T2*>(thePtr)));
}
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What I tried something as the following in several forms:
proc downcast*[T; T2](this: Handle[T] ): Handle[T2] {.cdecl,
importcpp: "Handle('0)::Downcast(@)", header: "Standard_Handle.hxx".}
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but when I compile I get:
Error: cannot instantiate: 'T2'
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How can I fix this?
