Re: Two warnings when creating a TreeStore

[José Alburquerque <jaalburquerque cox net>]

Murray Cumming wrote:
> On Fri, 2007-09-14 at 12:07 -0400, Jos�lburquerque wrote:
>   
> > Murray Cumming wrote:
> >     
> > > On Thu, 2007-09-13 at 11:15 -0400, Jos�lburquerque wrote: 
> > >   
> > >       
> > > > As far as gtkmm and inheritance, I found that if I use something like 
> > > > TreeModelColumn<MyBaseClass> in a TreeModelColumnRecord, derived members 
> > > > of MyBaseClass only use the virtual methods of the base class (not the 
> > > > derived class!), but if I use something like 
> > > > TreeModelColumn<MyBaseClass*>, dereferencing the pointer to the derived 
> > > > class later, does use the virtual (overridden) method of the derived 
> > > > class.  Thanks again everyone for your help.
> > > >     
> > > >         
> > > This is just like putting a Derived instance in a std::list<Base>. The
> > > Base part will be copied into a new instance in the list, but that
> > > instance won't be a Derived. This is how copy-by-value works.
> > >
> > >   
> > >       
> > I see, this is just standard C++.  I'm slightly new to C++ (coming from 
> > C and then Java), but I *am* learning as I go along. :-)
> >     
>
> Java doesn't really have copy-by-value for non-fundamental types.
> Everything is a reference there. The rough equivalent in C++ is to use
> smartpointers or regular pointers (plus your own memory management).
>
>   
That's right.  This is probably the most new aspect of C++ to me (I've 
had to learn about copy constructors, implementing an equal operator for 
classes, etc).  I also should brush up on when objects are copied by 
value, etc., especially when I'm working with derived classes, etc. 
(which as you know led me to the misconception I explained above).

I'm not completely alien to C/C++ memory management though.  I'm trying 
to use the class' destructors to manage objects which I "new"; as you 
say, I'm also using smartpointers where I  can and thanks to the 
excellent "manage()" function, I can leave newly created widgets in 
control of Gtkmm.

-Jose