prtx::ComparableContent Class Reference

#include <Content.h>

Inheritance diagram for prtx::ComparableContent:

Public Member Functions
virtual bool	compare (const ComparableContent &rhs) const =0
virtual bool	operator!= (const ComparableContent &rhs) const =0
virtual bool	operator< (const ComparableContent &rhs) const =0
virtual bool	operator== (const ComparableContent &rhs) const =0
Public Member Functions inherited from prtx::Content
	Content (const Content &)=delete
Content &	operator= (const Content &)=delete

Detailed Description

Interface for comparable content classes.

A word of caution: To compare content objects, do not directly compare pointer values (or shared pointers)! Content objects are typically implemented as thin wrappers to internal storage classes and do not guarantee pointer equality. Operate on the objects instead:

MaterialBuilder mb;
MaterialPtr m1 = mb.createShared();
MaterialPtr m2 = mb.createShared();

assert(m1 == m2); // WRONG!
assert(*m1 == *m2); // CORRECT!
assert(m1->compare(*m2)); // CORRECT!

To use shared pointers to content objects with STL containers like std::set or std::map, we recommend to use a de-referencing comparator like this:

template<typename T>
struct DeRefLess<std::shared_ptr<T>> {
    bool operator()(const std::shared_ptr<T>& a, const std::shared_ptr<T>& b) const {
        const T* pa = a.get();
        const T* pb = b.get();

        if (pa == nullptr)
            return (pb != nullptr);
        if (pb == nullptr)
            return false;
        return (*pa < *pb);
    }
};

---

The documentation for this class was generated from the following file:

• Content.h