Re: creating a vector of a vector of Gtk::ToggleButton

[Chris Vine <chris cvine freeserve co uk>]

On Saturday 30 October 2004 16:05, Carl Nygard wrote:

> > It might be useful to add a pure scoped pointer, one which does not clone
> > a referenced object (even if the referenced object is cloneable) and
> > which once initialised does not allow the identity of its referenced
> > object to be changed.  (Although I realise that a const std::autoptr will
> > do most of this for you.)
>
> patches accepted;)  If I get frisky I might attempt it.  My purpose for
> this was pure maintainership, because Kevin was no longer making it
> available.

It would probably require an extra option "flag" which would break existing 
code using it, but I will have a think about it.  Actually something like 
this will really come into its own when templated typedefs are in the 
standard, so you can do something like this:

template <class T> typedef ksvh::smart_ptr<T>::sbnwm shared_ptr<T>;

As it is, to provide this kind of convenience type you have to derive an 
entire new wrapper, viz:

template <class T>
struct shared_ptr: public ksvh::smart_ptr<T>::sbnwm {
  shared_ptr(T* p): ksvh::smart_ptr<T>::sbnwm(p) {}
  shared_ptr(const Shared_ptr& s): ksvh::smart_ptr<T>::sbnwm(s) {}
  shared_ptr() {}
  template <class U> shared_ptr(const shared_ptr<U>& s):
                                     ksvh::smart_ptr<T>::sbnwm(s) {}
  template <class U> shared_ptr& operator=(const shared_ptr<U>& s) {
    return operator=(shared_ptr(s));
  }
};

An option of locking the reference count would also be nice, for thread safety 
purposes, but that would then make it dependent on a particular 
locking/threading library and/or particular processor instructions for 
individual platforms.

> > However I notice that you release it under the GPL whereas Kevin Horn
> > released it as public domain.  To make the library more useful it would
> > be a good idea to indicate what the new code is (if any) which is
> > GPL-only.
>
> What makes you think that?  The actual smartptr source file only shows
> Kevin's original public domain license.
>
> Personally, I'd prefer LGPL for this, and I don't really want to get
> into which-piece-is-which-license for this library.  But I have to
> respect Kevin's wishes, and he placed it in public domain, so I'll cross
> that bridge when I get to it.

I don't think the LGPL works with this kind of templated library.  You would 
probably need to employ the modified GPL under which libstdc++ is distributed 
in g++ (this allows users to incorporate it, including headers, in users' 
code without GPLing the users' code).

Chris.