OK. Firstly thank you tobyink.
I understand you answer to my 2nd question. I asked this because I think $self is something like this pointer in c++. So as you indicate, I see in perl, class itself can be an invoker when as a class method, in the method, sometimes the first input what's commonly named $self is a class, sometimes is an object, no difference when using inside the method.
in reply to Re: how to make a package variable as c++
in thread how to make a package variable as c++