How do I create overloaded operators for boost pointers in C++?

Question

From this post I see that you can't overload operators for pointers: http://stackoverflow.com/questions/1419997/c-operator-overloading-of-for-pointers-to-objects

But is there any way I could overload operators for boost pointers? For example:

  boost::shared_ptr<ClassB> operator||(boost::shared_ptr<ClassA> lhs, boost::shared_ptr<ClassA> rhs) {
    boost::shared_ptr<ClassB> returnVal = CreateClassBSharedPtr(lhs, rhs);
    return returnVal;
  }

When attempting this, I get an ambiguous overload error (it conflicted with the built in operator||(bool, bool)). Any ideas to get around this?

Edit: Adding some more details below as to why I'd like to do this.

I'll try to explain what I'm attempting as best I can. What I'd like to do is make a "validator" object for maps that can check if certain properties hold. For example:

boost::shared_ptr<MyValidator> my_validator = IsEmpty("key name 1") && IsNotEmpty("key name 2") || HasNElements("key name 3", num)

Later, to validate a map:

if(my_validator.validate(some_map)) { ... }

I think I'm stuck with using pointers because I can't use pass by value (since I'm making use of polymorphism) and I can't use pass by const reference (since there would be temporary object created by nesting operators that would not exist later when trying to validate).

Edit: Added a new question specific to my problem here: http://stackoverflow.com/questions/3441608/implementation-suggestions-for-creating-an-expression-later-used-to-evaluate-the

Answer 1

Your approach should work, at least it works for me.

However, you will always run into the problems with ambiguous overloads when trying some user-defined conversions on rhs and lhs.

Answer 2

You certainly can:

#include "boost/shared_ptr.hpp"

template <class A>
bool operator||(boost::shared_ptr<A> lhs, boost::shared_ptr<A> rhs) {
    return true;
}

int main() {
    boost::shared_ptr <int> a, b;
    bool x = a || b;
}

Whether you can do what you are doing in your example, I don't know, as I'm not sure what you are trying to do!

Answer 3

Operator|| must always return a bool, so you can't (and for the sake of the sanity of your co-workers, shouldn't) do that. I suggest you use a regular function and give it a name that reflects what you are trying to do. GetValidatedPtr() or something simlar.