Re: [Re: [gtkmm] gtkmm2: no icons in stock menu items?]

[Spandan Bhatt <spandan_bhatt yahoo com>]

Hey thanx every oone for the helpful replies.
hmm
my idea of references was limited to being passed as
function arguments... well this is an easy extension.
Spundun
--- Carl Nygard <cjnygard fast net> wrote:
> On Thu, 2002-06-27 at 23:52, Spandan Bhatt wrote:
> > 
> > --- Christof Petig <christof petig-baender de>
> wrote:
> > > 
> > >   MenuList &list_view=view_menu->items();
> > Wow!! can you provide explanation for this
> perticular
> > usage(a link would be great)
> > I am talking about the C++ part of it.
> 
> It's clearer if you write it this way:
> 
> MenuList& list_view=view_menu->items();
> 
> list_view is a reference (which is in essence a
> pointer that has the
> syntax of a struct) to the MenuList of the view_menu
> object.  So when
> you modify list_view, you're really modifying the
> view_menu member data
> (remember the pointer bit).
> 
> Technically, you should use it:
> 
> MenuList& list_view(view_menu->items());
> 
> The compiler sort of re-interprets the assignment in
> the ctor as a
> copy-ctor when constructing references, because a
> reference must
> *always* exist, and to rewrite the first example as:
> 
> MenuList& list_view;  list_view =
> view_menu->items();
> 
> just doesn't make sense.  After the construction,
> list_view points
> nowhere.
> 
> It's also clearer in your mind, because if you do
> something later like:
> 
> list_view = other_view_menu->items();
> 
> for example to start modifying other_view_menu, in
> reality you have just
> done:
> 
> view_menu->items() = other_view_menu->items();
> 
> since you can't reassign a reference to refer to a
> different object once
> constructed.
> 
> Of course, this is all laid out in any good C++
> book, Stroustrop's would
> be the first that comes to mind.
> 
> Regards,
> Carl
> 
> 


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