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ROOT Version: 6.18/04
Platform: CentOS7
Compiler: GCC8.3
Dear enthusiasts and experts,
I’m trying to use a function accepting a template parameter as the following:
template <typename T>
class BaseClass;
template <typename T>
void bookInstance(BaseClass<T>& object);
(the bookInstance function is actually a member function of a different class, and it’s that class for which the dictionary is generated when I compile my code) where I have nested classes from BaseClass that inherit from it. So to provide overloads for these, I would like to do
template <typename T>
class BaseClass {
class Derived;
};
template <typename T>
class BaseClass<T>::Derived : public BaseClass<T>;
template <typename T>
void bookInstance(template BaseClass<T>::Derived& object);
However, calling this function with template type presumably being deduced from the argument gives me the following error from PyROOT:
import ROOT
obj = ROOT.BaseClass('int').Derived()
bookInstance(obj)
TypeError: can not resolve method template call for 'bookInstance'
Also, explicitly providing the template argument as the following gives me the following error:
import ROOT
obj= ROOT.BaseClass('int').Derived()
bookInstance(ROOT.BaseClass('int').Derived)(obj)
...
RuntimeError: could not resolve bookInstance<BaseClass<int>::Derived>(BaseClass<Derived>::Derived&)
Note the template type deduced from the argument is erroneously reported be ‘Derived’ when it is supposed to be ‘int’, as is the case if I simply print the object instance.
Interestingly, I can get my code working if I simply ignore these nested/inherited hierarchies and implement
template <typename Tany>
void bookInstance(Tany& object);
And I can effectively achieve the “specializations” that I want by defining other functions with additional parmeters that different Derived classes would have needed anyway. However, I don’t feel too good about this since ‘Tany’ is a bit too general for the types I want to implement, and also just curious as to why my original attempt is not working.
Apologies for not having a minimal example, since this is a bit deep into a piece of cod I am playing around with at the moment, but I was wondering if there was any indication of an issue or fix from the above information? Thank you for any help in advance!