GObject Interface vs Pure Virtual Class

["Kuang-Chun Cheng" <kcc1967 gmail com>]

Hi,

I'm studying GObject system and found that I can implement both
Pure Virtual Class (by setting all member functions NULL to make the class pure virtual)
and an Interface in GObject.

I'm a C programmer without much C++ experiences, but according
to my understanding ... pure virtual class in C++ is Interface.  Am I
correct ?

My guess is, in GObject, provide extra API to implement an Interface
is just another easier way to implement pure virtual class.
GObject interface will add more internal check which is better
than just set the member function to NULL, but ... there are
the same stuff, am I correct ?

Does any other good reason why GObject need an extra API set
for Interface ?

What's the different between Pure Virtual Class and Interface
in GObject system ?

Regards
KC